Continental C125/C145/O-300 General Information – Monty the Answer Man Archives

O-300 ENGINES CHOICES…
From: Dennis Mee (jmmee@nh.ultranet.com)
Subject: Re: N3812K
I just came across an O300D I can get everything I need to make it work except for a prop I guess that could be a problem without changing the crank. I really don’t need a vacuum pump since this will be a VFR restoration so I’ll keep looking. Thanks, Dennis Mee

Dennis,
I have an O-300A with a B&C starter. It is 10 or more pounds lighter than the O-300D I removed. I like the O-300D engine, the case is a little “heavier” than the “heavy” case 125 & C-145, and the cam is better. The cylinders are better too – but that point may be moot because for a good overhaul these days you just buy new cylinders. They are about $600 ea., and a first class cylinder overhaul costs almost that much, so you might as well buy new ones. That push button starter is really nice! (with either the O300D or the B&C starter) Keep in touch. — Jim

O-300 ENGINE QUESTION…  (3699)
From: Ed Lloyd (edlloydaustin@juno.com)
Subject: Re: 0-300A
Howdy Jim,
Feel like I know you what with all the questions and answers I’ve read on the net. The question I have concerns the 0 300A engine. What are it’s good points and what are the bad? I’m looking for a Swift and have two located, both with this engine. One has 337 hrs and the other has 915 SMOH. I would value your input . Regards — EdLloyd

Ed:
I like the O-300A, its the approved engine on the STC. I removed a “D” and installed an “A” with a B&C starter. The bad things are the cylinders are marginal for cooling and the lack of a controllable prop. I like one-piece props! (cheaper, and won’t throw a blade and kill you!) I can live with the takeoff performance. My temps. are usually pretty good, my baffling is in good shape. I have the new TCM cylinders and am keeping my fingers crossed, there is a service bulletin out on them. I think the O-300A is the most cost-effective engine for a Swift.  —  Jim

O-300D QUESTION…  (4199)
From: Ed Lloyd <edlloydaustin@juno.com>
Subject: 0- 300D
Jim
Tell me what I need to know about the 0-300D. What are the good features and what are the bad? I know it has a vacuum pump capability. Does it have any other features that make it better or worse in your opinion, than the 0-300 A? Regards, Ed Lloyd

Ed,
The O-300D is not STC’ed for the Swift, most are intalled on the O-300A STC with a field approval for the prop. The “D” and “C” have a different crankshaft flange. The best prop is a Sensenich 74DC-1-60. Some 172’s used this prop, with a lesser pitch. Most are found on Beech Muskateers. Others have used the McCauley EM series prop, but it is not as good a performer. The vacuum pump is a nice feature as is the key start.  —  Jim

ENGINE STC QUESTION…  (8599)
From: Greg Papendick <pappy@shianet.org>
Subject: Swift STC
Well it looks like I finally know what I am going to do with my Swift engine problem. I wrote to you some time back about my problems with getting my 0-320 installation approved and about the new AD on the prop. I have found a FWF 0-300 for sale and I guess I will be using that (includes metal cowl). My Swift is pretty close to original except for the FWF, battery relocation, and one piece windshield. This would allow me to return the Swift to pretty much original someday. My question for you, do you know anything about the 3 different STC’s available for the 0-300A? It seems to me that I read somewhere that at least one of these has a RPM limit to keep the horsepower to 125. I would like to make this installation as simple as possible.  Regards — Greg Papendick N3252K

Greg,
The best (and cheapest, $25.00) STC for the 0-300A installation is the Swift Assn. (Piedmont) STC. It does require a placard to limit the engine to 125 hp, but so what? 125 hp is 86% power for a 145 hp engine and the only way you can exceed that is at sea level with a climb prop. With the prop called for on the STC, a 73×59 McCauley, you can’t pull over 125 hp. They addressed the 125 hp restriction in kind of a dumb way. For legal reasons, you need a placard “do not exceed 2270 rpm at any time”. They left off “at full throttle”. I have mine above the rt. windshield, instantly viewable, but if you aren’t looking for it, you would never notice it. If you don’t mind spending the money, Merlyn has a GW increase for a 145 that allows full power and allows several different props, McCauley and Sensenich, both lower pitched which give better takeoff performance. — Jim

MOTOR MOUNT AD AND CUTTING ALUMINUM…  (10199)
Subject: 125/145 Motor Mount AD (64-05-06)
From: Bob Runge <ejectr@javanet.com>
Jim,
Reading the above AD, it says to use “Lionoil” to flush the mounting tube. What is “lionoil? I found “Tube Seal(Line Oil)” in Aircraft Spruce which sounds like the stuff that one would want to use for the AD’s purpose. Is it just a matter of dialect that “lion oil” sounds like “line oil” and “line oil is the stuff to use?

Bob:
I don’t know if lionoil is commonly available any more. I think that “tube seal” would work just fine. Yes, line oil and lionoil are probably the same. Regardless, I would not hesitate to use it.

O-300 COMPRESSION  &  PROP QUESTIONS…  (10499)
From: Ed Lloyd <edlloydaustin@juno.com>
Monty,
In talking to Tony Otto last evening, he said you were an authority on Continental engines. That conversation sparked a question or so in my mind so here goes. The engine in my bird (3856K) has less than 200 hrs. since major. In reviewing the engine log a differential compression check was performed at 109.1 hrs. #1 74/80 #3 78/80 #5 74/80 #2 20/80 #472/80 #6 76/80. The #2 jug was removed, cylinder honed, new rings installed on that piston and reassembled. Checked OK on subsequent run and compression check. When I had the pre-buy inspection done at 192.7, a compression check was completed as follows: #1 77/80 #2 75/80 #3 78/80 #4 75/80 #5 72/80 #6 78/80.

Since I’ve owned the bird, I’ve put maybe a half dozen hours on it. Question is, should I do another compression check to see if #5 is holding it’s own or continuing to decrease? Oil was changed following the pre-buy/annual and the screen checked normal. It had a few flecks of metal, however, Duane indicated that was normal. I’m seriously considering installing an Airwolf remote oil filter for better handling of the oil and ease of service. Additionally, there were no engine operating manuals, limits, etc., in the jacket file on the engine. The logs say I have a Sensenich 74 DC-0-60 prop installed now. On takeoff @ WOT, I’m turning about 2550, and the takeoff roll seems just a bit longer than I would like. It’s coming unstuck at about 60 and I’m climbing @ 80 MPH. On leveling, and reducing RPM to cruise I’m showing about 9.5 GPH on the Swifttronics. That’s giving me about 2350 to 2450 RPM at cruise. If I push over and get the bird “up on the step”, I’m cruising at 135 to 140 MPH. Not being familiar with the Cont., are these figures in a normal range or should I do some adjusting? Do you know if Continental Motors would have any kind of Ops Booklet I could purchase from them? If so, what should I ask for. Hope I’ve given you enough background for you to evaluate. Thanks in advance, Ed Lloyd

Ed,
Don’t worry about the compression reading. The O-300 series rarely seal up as tight as say, a 150 or 180 Lycoming. Readings of 80/60 and above are acceptable, what you don’t want is any exhaust valve leakage. With 80 lbs. pressure in the cylinder, listen at the breather for air leakage (rings) at the air filter for leakage (intake valve) and at the exhaust for leakage (exhaust valve). If the reading is less than 60 on any cylinder, run the engine and warm it up, then recheck before doing anything drastic. The Airwolf filter may be a good idea, it might help lower the oil temperature a bit also. With a 60″ pitch, you cannot expect too much initial acceleration, but that should be about right for overall performance and best cruise speed. 9.5 gph is a little too high at 2350 rpm. I lean whenever below 23″ or 2400 rpm, at 23″x2400 I burn about 8 gph. TCM has an Operators Manual for Aircraft Engines – O-300 and “C” series form X-30015, which is very good, it is just a little booklet and only costs a couple of bucks. It has power charts and a lot of information not found any other place. — Jim

COPY OF CONTINENTAL O-300 MANUAL AVAILABLE FROM JIM MONTAGUE…  (11199)
Jim Montague has copied the O-300 Ops Manual to an Adobe Acrobat document (“.pdf” file) and has offered to share it with interested Swifters. Making this file downloadable off the GTS Homepage was discussed but the idea was rejected due to space concerns. The file is 678KB, takes about 5 minutes to download, and requires an Adobe Acrobat 3.0 reader to read the file. (If you don’t have the Adobe reader it can be found and downloaded free from the FAA web sites.) Contact Jim Montague <monty747@aol.com>

CONVERTING FROM 125 TO 145…  (11199)
From: Larry LaForce <LaForce55@aol.com>
Subject: Re: 125 Cont.
Jim…
I was wondering what it takes to convert a 125hp Continental to a 145hp. Does it consist of only a stroke change with the same bore, or does the bore increase also? I am familiar with bores, strokes, rod lengths, pin locations, etc.etc. in the automotive racing world, but; I know nothing on the specifics on the 125hp Continental (bore, stroke, rod length, compression). Any info. would be greatly appreciated. Is there a manual available for this series engine? Thanks….Larry

Larry,
If the crankcase is a “heavy case” you need to change the crank, rods, pistons, cam and lifters. In other words, you might as well look for a complete O-300A, the later cylinders are better also. The earlier cylinders are legal, but the old “C” series cylinders are more prone to cracking than the newer ones. The bore is the same on all these engines. (4 1/16″) All these engines use the same overhaul manual. “Overhaul Manual for Continental C-125, C -145 & O-300 series Aircraft Engines” — Jim

MORE ON THE C125/145 DIFFERENCES ISSUE…  (11199)
Subject: Re: Engine
From: Larry LaForce <LaForce55@aol.com>
Jim…
Are there any visual differences between the C-125/C-145 and the O-300 engines? I assume that they use the same engine mounts. Thanks…. Larry

Larry,
The “heavy case” can be identified by 3 thru studs in the vicinity of the fuel pump. The “heavy case” has 3 – 7/16″ nuts on the fuel pump side, the light case has none. There are several “heavy cases.” The O-300 case is identified by smaller pipe plugs, 3/8″ pipe, at the front end of the oil galleys. The earlier C-125 and C-145 cases have 1/2″ pipe plugs. The “C” series cylinders have bronze inserts for the spark plugs, the O-300 cylinders have helicoils. The early oil sumps have only 3 bolts joining the accessory case, the later sumps have 5. The magnetos on the early engines are the Bendix SF-6-12. The later engines had Bendix S6LN-21 and the latest production O-300’s had the Slick 664 mags. The earliest engines had 12 amp. generators, the latest had 60 amp. alternators. From the factory, the early engines had a gray case and black cylinders and the late engines were painted Continental gold. the C-125 (short stroke) and the C-145 and O-300A & B have a large crankshaft flange, SAE No. 3, with 8 – 3/8″ nuts for the prop bolts. The O-300C and D have a smaller flange with 6 – 7/16 holes for prop bolts. There are other internal differences. The only problem with a C-125 is the early light case engines suffered crankcase cracks when used with a metal prop and turned up high rpm. A 125 with a heavy case is near “bullet proof” and will run 2700 rpm all day long as long as the early cylinders are not overtemped. The engine mounting is the same for all. — Jim

BAFFLING QUESTION…  (12399)
Subject: Re: engine baffles
From:Don Cumpston <don@penn.com>
Monty:
I am currently rebaffling my c-145 with thick silicone baffle material and would like to know the best way to seal the back of the engine against the block. Should you cut the material to the contour of the block or go to the block and fold 90 deg and lay against it? With so many curves on the block, folding the material like the old stuff was does not seem to seal very good. Your input would be appreciated. Thanks Don

Don,
Joe has the original baffle material and he can send the original size seals. When I changed my engine a couple of years ago I bought this baffle kit from Joe and although I didn’t use every piece, I found it useful for patterns. I believe you have a downdraft cowl. Many pieces of the baffleing are the same. I used the original type stuff next to the case and sealed it to the case with oil resistant RTV and laced the baffle with safety wire where appropriate. — Jim

TIME TO ROCK AND ROLL… (100600)
Swifter Larry Owen emailed to tell us that he has been in touch with US-Airparts <www.us-airparts.com> regarding their ad in Trade-A-Plane offering roller rocker arms for the Continental C-145 and O-300 engines. Paul Preibus of US-Airparts, (email: usap@mindspring.com), emailed Larry to tell him that the price for an O-300 would be $1050. They are currently out of stock but they should have some in stock in about a month. Quantity pricing is available if others might be interested (Swift Parts are you listening???). In any event, Paul suggested that anyone interested could email him at the above address if he could be of any service or if there are any questions. Thanks to Larry for passing along the information.

ENGINE MOUNT… (020100)
Subject: Re: engine mounts
From: Lee Davis <80730@aol.com>
Is there any difference between the 125 engine mount and the mount when you install a 145 or a O300 … just wondering. — Lee Davis

Lee,
No, you use the same mount. — Jim

CASE BY CASE… (020100)
Subject: C125
From: Lee Davis <N80730@aol.com>
How can you tell between a C125 light case and a C125 heavy case and is there any other little tidbits of info or hints that can be helpful ?

Lee,
The C-125 and C-145 cases made before about 1950 were “light cases”. The 125 has no AD notes, but it will crack if operated with a metal prop (as opposed to an Aeromatic), or with extended running over 2550 rpm. The 145 has a different harmonic and it will crack, period. Continental corrected the problem by going to the heavy case and in the 145, using harmonic dampers on the crankshaft. The last few 125’s had the heavy case in production, but most we see today are C-145 and O-300 cases. There are several p/n’s which can be called “heavy cases”. To identify a heavy case, the easiest thing to look for are 3 thru studs in the vicinity of the fuel pump. (or the lack of them on a light case) The light case will have nuts on the left side only, the area near the fuel pump will be lacking any 7/16″ studs protruding and no nuts, of course. The heavy case has 2 thru studs for every cylinder, but you can’t tell if a stud in the middle of the engine is a thru stud unless you put a wrench on it and turn it, then (maybe) the nut on the opposite side will turn.

The C-125-2 or C-145-2 has no significance re: the type of case or crankshaft. The cases made after about 1956 are better, they have a revised casting and the non-thru studs are tapped into blind holes, so they have fewer oil leaks. The earlier cases were tapped into the inside of the case and had engine oil splashing on the stud, which tended to seep oil to the outside of the engine eventually. If you are building up an engine, the best case to use is from an O-300A or O-300B.

Other C-125 notes: The “C” series cylinders tend to crack, they are not worth spending the money for changing all the guides and seats. The original magnetos, the SF-6-12’s, have no AD notes, but they are not worth spending the money for a complete overhaul. The fuel pump has an AD calling for inspection at annual, it’s the same p/n fuel pump as an O-300, which has no AD note. Further comment on request! An O-300C or D case can be used on any earlier engine, C-125, C-145 or O-300A or B. The “C” can be used if the “C” starter pivot is used. The “D” can be used if either a “C” starter pivot or a B&C starter is used. There is an oil passage to the starter bushing in the O-300D which may need to be blocked off if using the B&C starter. — Jim

SNAP, CRACKLE, POP… (040100)
Subject: Re: O-300 Carb/Mags
From: Steve Roth <stevenroth@aol.com>
Monty: I have an O-300A with old Scintilla “Lunch box” mags. The engine runs fine (except for problem described below) with minimal mag drop. Carb appears to work correctly (RPM peaks when mixture pulled to cut-off). The engine starts easily and idles nice. With full rich mixture, as I increase the RPM for taxi, especially using my vernier throttle (say, to 1100-1400 RPM), it crackles and pops out of straight pipe. If I “clear” the throttle with a burst of higher RPM, it will settle down. Runs fine in the air in cruise rpm (2200-2700). It does not hesitate when I push the throttle in. It does not crackle when pulling throttle for landing. I can’t recall if it does this only when it is cold or if it does it all the time.

This situation reminds me of when I have the mixture out for ground operations (taxi, etc.) and try to give it throttle which requires more fuel. It snorts and crackles then also, but I have experienced that in my C-172 with O-300A so kinda know that is normal. It has had this condition since I had it. My mechanic at last annual was not worried about above condition since engine ran so smooth other than a narrow band in middle of RPM range. Other aspects of engine are excellent (compression, plugs, etc.). Can you shed any light on this? I am thinking carb. Thanks, Steve Roth & N2397B

Steve,
I suspect that when transitioning from the idle circuit to the main fuel delivery nozzle there is a moment of too lean fuel delivery. To correct this you might need a new accelerator pump. A simple fix might just be to put the link for the accelerator pump discharge in a hole which will discharge more fuel. Since your airplane has always been in a warm climate, maybe the link in the “minimum” hole. Try one of the other two holes. If you have a C-125 carburetor, I would suggest you get a new or reman. carb. for an O-300. The 125 carb is a 10-2848. They will take the 125 carb in as a core now. — Jim

TROUBLESHOOTING MANIFOLD PRESSURE… (040100)
Subject: Continental O300 D Manifold Pressure
From: “Ed A. Lloyd” <edlloydaustin@juno.com>
Hi Jim, Got a question concerning manifold pressure on the O300D engine. The gauge in 56K hasn’t worked since I’ve had it. I was told there is a restrictor fitting in the intake manifold where the manifold pressure line is attached and it could be plugged. I removed that restrictor fitting and it was not plugged. I removed the gauge and applied a vacuum source and the gauge did not move so I promptly sent off and had it repaired. I reinstalled the gauge, and much to my surprise, when the engine was cranked , the manifold pressure gauge still didn’t do so much as flicker, regardless of the power setting. Now I’m being told that there should not be a restrictor fitting in the intake manifold! Any suggestions? Tomorrow, I’m going to remove the gauge and disconnect the line from the manifold and see if the line itself could be plugged. If the line is open, should I tap into the manifold with a normal AN fitting without a restriction and try that? Thanks for you help and Cheers…..Ed Lloyd

Ed,
I have not seen a restrictor fitting at the intake manifold end of an O-300 manifold pressure line. There is usually one in the guage itself. Many years ago, I had a GC-1A with a manifold pressure line plumbed into the little manifold directly below the carburetor, every so often, the gauge would partially fill with gas! I installed a restrictor fitting. The manifold pressure line on an O-300 normally goes to a 1/8″ pipe nipple or inverted flare fitting on the rt. intake manifold, but it can just as well be routed to the 1/8″ pipe primer port on the top of a cylinder. (some late cylinders don’t have these) It seems like the gauge might flicker, but it works ok in my experience. To check out your gauge, with it removed, just stand in front of a mirror, put the AN 4 or inverted flare fitting, whatever is in your gauge, in your mouth and suck as hard as you can. You should be able to draw it down 10 inches or so. If you can’t get the needle to draw down something is wrong with the gauge. With the gauge removed from the aircraft, start the engine.

It might idle petty bad. Put your finger over the end of the manifold pressure line and make sure there is suction there. If there isn’t, obviously the line is blocked. — Jim

MANIFOLD PRESSURE FIXED… (040200)
From: “Ed A. Lloyd” <edlloydaustin@juno.com>
Hi Denis, re: the comments about manifold pressure in the newsletter. It took some digging but I finally found the problem. Checked the gauge with a vacuum pump and it was ok. Disconnected the line from the manifold and it held vacuum with both ends of the line loose!!! Tried blowing compressed air through the line in both directions and it was plugged. Traced the line to where it went through the firewall and there was a firewall AN fitting. Removed the line on the firewall side and blew air through the line both ways ok. Looked at the fitting where it protruded through the firewall and there was the problem, the fitting was plugged with what appeared to be drill shavings. Blew out the remainder of the line, reassembled the system and walla, it worked as advertised. Now I’ve got manifold pressure. Just shows, you gotta think it through and do complete trouble shooting. Cheers….Ed

ENGINE DATA PLATES…  (050500)
From: Larry Rengstorf <swiftair@pacbell.net>
Subject: Data plates
Hello Jim – again, I have a couple more questions, this time about engines === We are not real sure what engine is in this airplane we are building up. It came out of the plane originally, and the plane came out of a trade school. The engine did not have a data plate and the school isn’t any help. No log books either!!! Don asked that I talk to you and ask these questions=
1. How do you get a new data plate ? thru Continental ?? or ? Do you need the serial number to get a new data plate ??
2. How do you tell what the serial # is ?, any tell tale info. (We rebuilt it here in the Sea Fury / R-4360 engine shop in Hamilton’s hangar) & could not find any serial numbers, or anything that even looked like ser #. The only numbers were cast #s on each side of the case halves.
3. How do you tell what the engine is ?, According to the info in the Continental over-haul manual, it is a 0-300-B or a C-145-2. (It has the orifice for the 2 position prop control on the lower left front of the engine.) The starter is the inline type- with the pull cable. No vacuum pump pad either. Thanks Again, Larry R.

Larry,
To get a data plate from TCM is a big deal. They want a letter from the FAA verifying what it is etc. A C-145-2H can be distinguished from an O-300B by several minor differences:
1. The galley plugs at the forward end of the oil galleys are bigger on the C-145 — 1/2″ pipe vs 3/8″ pipe. (I think that’s correct, I never could eyeball pipe sizes)
2. The splitter baffle above the carburetor is a riveted in sheet metal piece on the C-145 and cast integral on the O-300B.
3. The “C” series cylinders have bronze spark plug bushings. The O-300’s have helicoils.
4. If the cylinders are removed, the C-145 cases have the cylinder base studs tapped thru and are “wet” studs – they can potentially leak oil. The O-300 studs are are “blind” – they revised the castings in 1955 so the studs aren’t tapped thru.
5. Look for the casting date. Cases cast from 1948 thru 1955 are 145 cases. From 1955 to 1967 are O-300 cases.
6. Details such as carburetor and magnetos may be different but these parts are so easily changed they are not valid for identifying the engine.

Can’t you just find a different data plate? If I had a C-145-2H data plate laying around I would send it to you. I have a C-125 data plate if that would do you any good. — Jim

PS If you want that last bit of speed to beat Denis you probably need a Sensenich prop. But a McCauley can be reworked to provide virtually the same speed and it will climb better. The secret is to narrow the tips to near the repair limit and to round the tips. Sometimes it is then necessary to pitch it up a couple inches to avoid overspeeding. A McCauley with wide tips that will only turn 2500-2700 rpm WOT level will be slow.

ENGINE SWAP…  (060300)
Subj: 0300A
From: Dennis Friedrich <dennisd@crcwnet.com>
In changing from a C125-2 on my Swift to an O300A, is there anything that need to be altered to install the engine? Thanks.

Dennis,
The engine will bolt right on with no alterations required. Oh, there might be a few detail differences, like the size of the fittings in the engine case for the oil cooler and the mag. P-leads if the magnetos are different. Some of the baffleing may require trimming to fit the beefier fins of the O-300A. If you switch generators, the regulator may need to be changed to match. — Jim

SNAP, CRACKLE, POP REVISITED…  (060300)
Subj: O-300A Questions
From: Steve Roth <stevenroth@aol.com>
My O-300A engine pops out of the exhaust at low-mid RPM (circa 1000-1500) on the ground. Also, as I throttle up it really snorts and runs slightly rough (stumbles) as I go from high idle (1000 RPM) to around 1400-1500 RPM. It acts as if I have the mixture control out and one or more cylinders are not getting enough fuel. Once above 1400-1500 it runs smooth. It always runs smooth in the air even as I come back on the throttle when landing. The engine appears strong and I have no problem getting full RPM. This characteristic has not changed over time. One source told me it is probably related to the need for the “pepper box” nozzle in the carburetor, that the old style atomizer is causing it. A carburetor source told me that no, the carburetor does not affect the mid-range. It appears to not be the accelerator pump since it snorts while at low/high idle and does not hesitate when in the air. Another source at MMI who heard it snorting says it is related to the intake valve(s) not closing complete. But, it does not backfire through the carb — it cracks out of the exhaust. Same person said it might be related to weak valve springs, and/or cam and/or push rod(s). Okay, but it runs well in the air and easily runs up to redline (I have a climb prop – Sens DR1-59). I perform oil analysis and levels are nominal. The overhaul 500 hours ago was done with all ECI (Texas) rebuilt components. Any ideas where to start looking? I still suspect the carburator. Thanks, Steve

Steve,
I would get a new or reman. carburetor. You can get a Consolidated for about $550 or a while back Precision had no remans in stock so they were selling brand new units at their reman price, about $600. I do not think the valve springs would cause that problem at that rpm. Valve springs can cause the engine to apparently miss at full throttle, low rpm, such as climb with a fixed pitch prop. I’m not sure I agree that the accelerator pump is not at fault. Did you check which hole the link was in? I’m wondering what cam and lifters are in your engine. The C-125 lifters and the O-300 cam are not compatible, but I doubt if you have that combination because it probably wouldn’t have run 500 hrs! — Jim

SOMETIMES IT IS THE SIMPLE THINGS… (060400)
From: Stephen James Martin <stevmart@pottsville.infi.net>
Subject: Re: June #3 GTS Internet Update
Re: The Snap, Crackle, Pop Question in the last update:
I had the same problem with my Luscombe and chased all the same suggestions listed in the E-Messages. I finally found that it was a simple vacuum leak in the intake runner for No. 1 cylinder. Check all the intake fittings/gaskets etc. before springing for a carb. Can’t hurt and doesn’t cost anything (except maybe gaskets). — Steve Martin

ANOTHER VOTE FOR “INTAKE LEAK”… (060400)
From: Bob Webster <bob-jewell@wk.net>
Subject: Rough Engine
Dear Denis,  I goofed and deleted the last newsletter that was sent so I don’t have the E-dress, but if you have it with the one where the guy had the engine that was popping and banging at low RPM, but would smooth out and be fine after he was up above 1000 or 1200 RPM tell him instead of doing all the mag work and all that to first check for an intake leak. This is apparently pretty common on the 125/O-300 engine and all it takes is replacing the paper intake gasket. My neighbor has a 145 Swift and he had the problem and I had it on a Lyc O-360. It runs rough at low RPM because it is sucking AND blowing due to valve overlap, but at higher RPM it is just sucking and seems to run fine, but there is probably a lean cylinder now. I am not an expert, but my guru that lives down the street (Charlie Cummins ) said to pass the word on before the guy spent some big money for no results. And Charlie knows! Hope it works. — Bob Webster

MONTY AGREES THAT STEVE ROTH’S ENGINE WOES COULD BE AN INTAKE LEAK…  (060500)
Steve,  I see in the GTS Internet update several guys are telling you that you might have an intake leak. They may be right. I presume you have a manifold pressure gauge. Is the reading steady? What does it read at idle? What does it do when the engine is “stumbling”? All O-300 cams are p/n 530803, but they changed them many times. The early cams are “pointies” (more pointed lobes) and the later cams are “roundies” (more rounded lobes) The early cams idle at 10 -12 inches of manifold pressure. The later cams idle at 15 -16 inches of manifold pressure. (more overlap) If you have a higher reading than 16″, you have a leak. Also, if the needle jumps around, you have a leak or a broken valve spring. Try and inspect the gaskets at the intake elbows. (not real easy sometimes) You might try removing the intake manifolds and the intake elbows and replacing the intake elbow gaskets. — Jim

STEVE SAYS THANKS…  (060500)
Subj: Re: O-300 running
From: Steve Roth <stevenroth@aol.com>
Unfortunately, I do not have a manifold pressure gauge installed. Nevertheless, I am now convinced an intake leak is the prime candidate. It is time for annual anyway and I need to replace the rubber intake hoses so I will have them pull the manifolds and check the gaskets. I will have the man pressure gauge installed at the same time. I appreciate everyone’s help on this irritating problem. Thanks – REGARDS, Steve

Steve,
I really believe in a MP gauge – I don’t understand how anyone can run an engine without it. It also can be a handy trouble shooting tool – like in this instance. When flying a Swift, I just never exceed 24″ continuously. RPM like 2600 never bothered me. If your prop for instance, turned 2300 RPM at 24 or 25 inches it would not be pitched right. My prop for instance, turns 2600 RPM at 24″ and 2500 RPM at 23″, which I think is just right. — Jim

“BEEFIER” CRANKSHAFT FLANGE…  (060500)
From: Bob Sandberg <swifter@bellsouth.net>
Hey guy, I appreciate all the information I get from you on the Swift! I need to know what model # of the O-300 has the beefier crankshaft flange. Is there an STC for the 0-300D? I also need the 3 pieces of metal that the rear glass sits in on the GC1-A (just fwd. of top turtle deck). I have the pattern but not the tool to run the bead the glass sits in. — Bob Sandberg

Bob,
I was trying to reply about what you wrote Bob Runge re: wing fittings. Bob got his copy ok, but the copy I sent to you came back. I wouldn’t say any model O-300 has a “beefier” crankshaft flange, but the O-300A & B have the bigger (8 bolt) flange and the O-300C & D have a smaller (6 bolt) flange. The O-300D is not STC’ed. Many have been installed using the O-300A STC with a field approval for the different prop. Sorry, I can’t help you on the 3 pieces for the 3 windows. Some metal wizards like Mark Holliday and Duane Golding have fabricated the parts, but I don’t have that capability. — Jim

OIL DRAIN PLUG SIZE… (080500)
Subj: Oil Drain Plug
From: Richard Aaron <raaron@pica.army.mil>
Jim,
I just got a quick drain plug for my oil sump, which has a 1-18 thread. I was just curious how come all the catalogs list this thread for the C145 but not the C125? Also, there’s no lug on the sump for attaching a safety wire. I’ve been tying it off to spot on the rear baffling; there seems to be no other choice. How come such an obvious thing was omitted? Do you have any other recommendation? Regards, Dick, N2405B

Dick,
The original 125 sumps had a smaller size drain plug. If you have a drain plug the same size as a 145, your sump has probably been replaced. I safety mine to the engine mount. — Jim

WHEN PUSH COMES TO SHOVE (PUSHRODS)… (090300)
Subj: Pushrods
From: tom@electrodesign.to (Tom Numelin)
Jim, I pulled a cylinder off to fix an oil leak and I forgot to label the pushrods so I couldn’t tell which one was for the intake valve and which one was for the exhaust. When I stood them up one was clearly longer than the other by maybe 15 thousands. I thought they were all the same and interchangeable. Does it matter which one goes where/ My mechanic said he thought it didn’t matter since they are hydraulic lifters. Tom Numelin

Tom,
The pushrods are the same, BUT, there are two lengths of pushrods listed in the parts manual, standard and P.030. (plus thirty thousandths) When setting up the engine at overhaul and with the lifters bled down, (no oil), the rocker clearance should be .030 to .110. If the clearance is over .110, say .125, a longer pushrod must be installed. The rocker arms are not adjustable, so the only way to change the clearance is to grind the valve face, or grind the valve seat, or to install a longer pushrod to decrease the clearance. Or grind the valve stem or rocker arm to increase the clearance. I also have seen P.070 pushrods listed but I don’t know if they are genuine TCM parts. Once the engine is run, the lifters pump up and are filled with oil, the clearance can no longer be checked. The only way to check the clearance is to remove the cylinder and pull the guts out of each lifter and wash all the oil out and reassemble without oil. BTW – pulling the pushrods out can be hazardous on an early engine – the lifters have no circlips and the pushrod cup can come out part way with the pushrod, then get cocked in there and break the lifter when the engine is rotated. If the cylinder is removed it’s no problem because the parts can be easily reassembled while the cylinder is off. Did you grind the valves or valve seats? If so, you probably can reinstall standard pushrods. It sounds like you have one P.030 pushrod. If the clearance is below .030 the valve will remain open and will leak. If the clearance is over .110 the engine will clatter from the excess valve clearance. I would install two standard pushrods. If, after an hour or so of running, there is any rocker clearance, install the P.030 pushrod. There should be “0” clearance after the engine is run and the lifters pump up. Standard pushrods are easily obtained from any engine overhauler. I have hundreds of them in my shop, left over from overhauls where P.030 pushrods were installed. It’s the P.030 pushrods that are valuable. — Jim

CONSIDERING O-300…(120200)
Subject: Re: O-300A
From: Larry LaForce <LaForce55@aol.com>
Hello Jim… I read all you had to say about the O-300A engines in the archives. It seems to be your favorite which is the main reason I’m considering one. I have located a fairly low time O-300A minus the carburetor. I noticed one archive article where someone was running a C-125 carb on their O-300A. Will the O-300 perform OK with the C-125 carb? The reason I ask is I have a C-125 carb that I could use. Thanks…… Larry LaForce N80844

Larry,
The 125 Carburetor, a 10-2848 will work just fine on an O-300. Actually, the Swift Association STC says, “Install the O-300A engine using same…..carburetor…no modifications necessary. The 125 has 18 fewer cubic inches of displacement and the manual says there are “different carburetor metering parts”. I wondered about that one day so I dismantled a 125 carb and a 145 carb at my workbench. The jets were all the same, at least on these two carburetors. The 172’s that most O-300’s came in were meant to be flown by low time pilots, so as a precaution, Cessna may have jetted the O-300 slightly rich to provide more cooling. The 125 (10-2848) nozzle is p/n A47-652 and the 145 (10-3237) is p/n A47-702, but that’s the only difference I have found. I have several hundred hours behind an O-300 with a 125 carburetor and never had any negative experience that might indicate too lean operation. — Jim

MORE O-300A…(120200)
Subject: Re: O-300A
From: Larry LaForce <LaForce55@aol.com>
Jim… A few more questions about the O-300A’s. What were the production years and are they all the same? Is one year preferred over the others? Thanks…. Larry

Larry,
I think the one I have now was made in 1959. They should all be pretty much the same. The crankcases were revised from the C-145-2 so the studs are “blind” – they changed the castings so the back side of the studs is not exposed to engine oil – and possible oil leaks. The later camshafts are possibly better – but many camshafts have been replaced in the 40 some intervening years. All camshafts are p/n 530803, but the later ones have a suffix, such as 530803-AN or AT or AU.

The part number can be found near one of the aft lobes and if it goes around the cam, it is a late part and if it is longitudinal it is an early part. The early cams are “pointies” and the later cams are “roundies”. (The shape of the lobes; as you know, a racing cam is more rounded) You can identify which cam you have simply by running the engine if you have a manifold pressure gauge. At idle, if the manifold pressure if at the bottom of the scale it is an early cam. If it idles at 16″ MP, it is a late cam. (more overlap) The early cams do have their backers, some claim the shorter timing brings the useable rpm down into the range where the prop does its best work. Regardless – there isn’t much difference – TCM never changed the horsepower rating of the engine, altho I suspect the later cam is good for a few more hp at a few more rpm. The O-300A’s were made from about 1955 to 1961. — Jim

MONTY DOESN’T WANT TO BE A LAWYER. AND WE’RE ALL GLAD FOR THAT…(120300)
Subj: O-300-A STC
From: Wes Knettel <wsknettl@centuryinter.net>
Jim,
I was reading the Dec #2 update. You mention the use of the 125 carb. My experience with STC’s for engine changes indicates you must either supply a O-300-A IAW it’s TCDS or you must also have an approved STC for engine alterations. Since the carb, starter and etc are part of it’s TCDS. I am not familiar with this STC. Is there in fact 2 seperate STC’s for the switch to the O-300-A? One for the airframe and one for the engine. Just curious, Wes K

Wes,
Only one STC is involved, SA1-326, the “A” standing for Airplane (or Airframe?) An engine STC would be “SE”. I would not want to be a lawyer interpreting the STC. I will quote Step 2.

Step 2. Install Continental O-300A engine using same or identical motor mount, bolts, baffles, exhaust system, wiring, plumbing, fuel pump, carburetor, and cabin heater systems; and oil cooler and lines, no modification necessary.

I would not make too much out of the interpretation of that statement. Yes, you are correct in what you say, but there are many loopholes. A 125 carburetor might be considered a minor alteration. The engine is rated at 125hp. — Jim

NUTS ABOUT D/G AND A/I…(010401)
Subj: Vacuum pump on C-125
From: Michael Ward <millerk@gte.net>
Jim,
I read your response to a question concerning the lack of vacuum pumps on C-125 and C-145 engines due to the stock cowl not having enough room for a belt driven pump. If I was still NUTS enough to want a D/G and an A/I, what would be your best suggestion. Buy electric instruments or by a different cowl? Do you have an idea of the expense, and where could I find the proper cowl? Regards, Michael Ward

Michael,
If you want to install a fiberglass cowl, you might try advertising in the various publications that you will trade. The stock cowls are highly sought after these days, so you shouldn’t have any problem there. Alterair makes the fiberglass Swift cowling. I have no idea of the availability, they have a link with phone numbers off the Swift site. I don’t know the current price of their cowl new. Having said that, I would change the engine to an O-300D if I wanted a vacuum pump. I must tell you, I had an O-300D in my Swift until a couple of years ago. I had the vacuum pump drive blanked off! An electric turn and bank gives me the ability to make a 180 degree turn, which is all the instrument capability I feel I want or need. — Jim

(Editor says… My Swift has an O-300-B so that means no vacuum pump of course. The previous owner installed a full gyro panel with all electric gyros. This is fine for that urgent situation where one must give serious consideration to the chance that one must abandon mother nature’s horizon to complete one’s flight. With all electric “tilts and spins” you are creating a situation when all your gyroscopic eggs are in one basket. Not recommended for routine IFR ops. The standard set up in most IFR light aircraft, as you know, has at least one instrument, usually the attitude indicator, being vacuum driven. In many applications, like Cessna for example, both the A/I and heading indicator are air driven. The wisdom of splitting your power sources is obvious.)

LOCK JAW…(030101)
Subj: O-300-B
From: Denis Arbeau <arbeau@napanet.net>
Jim,
Occasionally, after flying and I shut down my O-300-B engine, the engine is hard to turn by hand with the prop. For example, I shut down and the prop stops about 10-20 degrees away from horizontal. When I push the airplane into the hangar I like to make the prop horizontal. Sometimes when I go to put the prop to horizontal it is very hard to move. If I move it back the other way it frees-up. Just a couple of minutes later everything is just fine the prop moves completely freely. It doesn’t do this every flight. Maybe 50% of the time. I’m wondering what I have going on here… Denis

Denis
I have noticed that phenomenon before with various engines, not just O-300’s. I think it has to do with the heat expansion of the piston/rings in the cylinder. The rings may have a carbon build up behind them in the ring groove and cause a lot of ring drag when the engine is at certain stages of heating/cooling. A “bad” thing which is possible is, the piston pin plugs are wearing. Have you noticed shiny aluminum in the oil? O-300’s have been known for this. Sometimes, they go all the way to TBO and if the oil is analyzed, it will show excess wear on the piston pin plugs noted because of aluminum particles in the oil. If the exhaust valves are on the verge of sticking, the carbon on carbon could cause drag also. I would rule out a cause such as a generator bearing because it doesn’t seem to be getting any worse. So what to do? Keep doing regular compression checks and oil changes. Use Marvel Mystery oil. Avoid 100 LL if possible, always use TCP with 100 LL. — Jim

O-300 PARTS CONCERNS…(030501)
Subj: O300B Overhaul
From: Brian Ulmer <bkulmer@c2i2.com>
Hello Monty, got your name from the swift guys and if I may bother you with a question, I have one. Recently I called El Reno for an overhaul list for my O-300-B to see what the prices were. Anyway, they said the mains for the -B were not made anymore. Are you aware of this or ? … I love this engine and appreciate your passing around what you know about it. Best regards, Brian Ulmer

Brian,
The only bearing that is different in an O-300B is the front main. It has oil holes and a groove for the oil controlled prop. You might try Fresno Airparts in Fresno, CA for the O-300B bearing set. If you have no intention of using a controllable prop, an O-300A, C, or D bearing will work just fine. When the engine is disassembled, a good machinist could transfer the oil holes and groove to an O-300A type bearing and using the “B” bearing as a pattern, make a “B” type front main bearing. Also, the front main bearings seldom show wear, so the front main could simply be used over. WagAero had some surplus C-125 and O-300 front main bearings some years ago, I wonder if they have any left? A phone call might locate some front main bearings. The O-300B and C-145-2H front main is p/n 530516. The C-125 and all the other O-300’s take a 36170. — Jim

C125 vs O-300 CARBS… (060301)
Subj: Carburetors
From: Bud England <Dalswift1@aol.com
Jim:
I’ve got M/S carburetors P/N 10-3237 and P/N 10-2848. They came off of the 145 and 125 respectively (I think!). How can I find out which on would be preferable, performance-wise, for the 145? Bud

Bud
Either will work but the 10-3237 is the correct one for a 145 and the 10-2848 is correct for a 125. Performance probably depends a the individual carburetor. Probably the 10- 3237 is preferred although the Swift Association STC for the O-300A calls for a 125 carburetor. I would use one of your carbs for a core and trade it in and get a new Precision Carburetor. They run about $600 with core. — Jim

SLICK MAG TIMING FOR C-125… (060401)
Subj: Slick Mags
From: SwifterDon@compuserve.com (Donald Thomson)
Monty:
I just got off the phone with Howard Means (Scappoose, OR Swifter), who’s reinstalling the Slick mags on his C-125 Swift. he wanted to know the settings. I think the manual says 28 & 30 degrees, can you confirm??? I seem to remember the O-0300 is set at 28 & 26 degrees…… I suggested that he check with you, but I think he was calling from his hangar and I was planning to fly up that way this morning anyhow… maybe I could stop by and talk with him….. Any thoughts?? Don

Don
The 125 is 30 degrees Left and 28 degrees right. It’s the 145/O-300 that is 28 & 26. — Jim

WOW, A DASH ONE??? (060401)
Subj: C-125-1
From: jerryk0jj@columbia-center.org (Johnson Gerald A)
Hi, Maybe you can help me with a problem. A fellow aircraft owner asked if I would help time his continental C-125 on his Swift. I looked up the TCD for timing info and got 28 R and 30L no problem. He had the older SF6 mags that had just been gone through and repaired. On looking at the engine I assumed that the left mag would fire all the bottom plug and right mag all the top plugs. The mag harness was split like Lycoming the left mag would fire left bottom two plugs and then the top two right plugs. I can’t see this being correct or am I missing something. I thought the idea of firing the bottom plugs first was to correct for exhaust delusion and get the flame front too meet at the same time when the top plugs fire 2 degrees later. He said he had checked with a couple of different people and they said that’s the way the harness was to be. This is the first swift I have seen and it is all original with C-125-1 engine. Before doing anything I would like to find out just how the plug harness was originally installed. Retired A&P Jerry J.

Jerry
Wow, a C-125-1? Is that right? I have only seen two of those in my life, almost all C-125’s are the C-125-2 version. It doesn’t make much difference whether the plug wires go to the upper or lower plugs, just so each mag fires 1-2-3-4-5-6 in that order and is routed to cylinders 1-6-3-2-5-4. Originally, the Left magneto fired the lower plugs and the Right magneto fired the upper plugs. Someone along the last 50 years evidently changed that. Since the Left mag fires at 30 degrees and the Right mag fires at 28 degrees mixing the leads from one mag from top to bottom will cause the timing to vary by 2 degrees from that mag — which will not make much difference. I just re-read your letter and it sounds like you are working on a 4 cylinder engine. A C-125 of course, is a 6 cylinder engine. Am I missing something? Regardless, the left mag should fire the lower plugs and the right mag the upper plugs. — Jim

ALLS WELL THAT ENDS WELL IN THE DASH ONE DEPARTMENT… (060401)
Subj: Re: C-125-1
From: jerryk0jj@columbia-center.org (Johnson Gerald A)
Thanks Jim, Yes I slipped should have said bottom 3 and top 3 plugs. 90 % of engines I have worked on are 4 cyl. I know all the smaller continental 4 cyl’s fire the bottom ones first. Also the engine may be a dash 2 will have too take another look as thought I saw -1. same timing on either one. Since they have it split up like that can’t see any reason for timing 2 degrees apart. Nice web site will have to see if the owner of this Swift has use of internet and can check out all the useful info. Thanks again; Jerry

IS THIS THE RIGHT CARB??? (070101)
From: Anonymous
Subject: a question from anonymous
The question about carb number got me wondering and after checking ….. it appears that the carb on my C-145 is a # 10-4252, which is not one of the ones listed. Not that anybody has ever noticed in the last twenty years it has been in this area. It is a model MA3SPA. Any ideas what this is and how appropriate this carb is ? Is this carb different enough to be a performance issue?

Dear Anonymous: YEP! That is a carburetor for a C-90! It has a smaller venturi than a 10-3237 or a 10-4895, the two listed p/n’s for the O-300. I would say you are losing 10% to 20% of your power. — Jim

CARB AND PROP ADVICE FOR THE C-145… (070501)
Subj: C 145 2F Carb?
From: Wilsey2
Jim, I have been following your discussion because of my similar problem, but still have lots of questions. I have an MA3SPA Model #10-4895-1 which I believe is one of the two that you said is approved for my engine. However, my Continental “C” Series maintenance and overhaul manual says on page 44 that it should be a Model #10-2848. I do know of a 125 with a 10-2848. My compression is good on all cylinders, I have had both mags rebuilt, all new wiring and plugs, rebuilt the carb, checked valve and mag timing several times and still can’t get over 2050 static rpm (sea level) or 2300 on the take off roll. It just seems slow on acceleration. I should also mention my prop is a McCauley fixpitch IA170/DM7458. diameter is 74 1/2″ pitch is 58″. Sincerely, Larry D. Wilsey N80878

Larry
You have the right carb for a C-145. A 10-2848 is the carb for a C-125. I suspect your prop is near full dimension. If the tips are wide, as on a new McCauley prop, it won’t turn up or perform like a prop that has had the tips narrowed or rounded. If you have your prop reworked, or find another one to try out, get a 1A170DM7359. The 74 dia will not perform as well as a 73 dia on a Swift. I like to round the tips on a McCauley — that unloads it a little for higher static rpm and better takeoff performance. If the tips are not rounded, the chord should be narrowed to near the repair limit. — Jim

MONTY IS ON THE “CASE”… (080101)
Subj: c-125
From: Greg Milner <tldrgred@execpc.com>
Jim,
A gentleman at Oshkosh told me to go with 145hp or more. I like 2000ft. grass strips. I`m interested in one in Michigan but am leery of cracks in the case also. Where exactly do they crack?  Greg

Greg,
There are very few “light case” 125’s around anymore. Is that what it is? The “heavy case” engines can be identified by the 3 ea. 7/16″ studs and nuts in the vicinity of the fuel pump on the right crankcase half. (there are also 2 thru studs per cylinder, but they are hard to pick out visually) The light case engines usually crack internally. The first indication that the case is cracked is an excess of aluminum in the oil screen, and a lack of torque on the 2 forward studs for #1 cylinder. There were a few light case C-145’s too, but they were all made in 1948 for Aeronca Sedans. All O-300’s are “heavy case”. You should buy any light case 125 with the idea that a 145 engine is going to be a necessary purchase sometime in the next year or two. Beside the case problem, a 125 is not a good 2000′ strip airplane. Good luck! — Jim

O-300D CAMS… (090301)
(Editor says: Warning… highly technical stuff follows… please do not read if under the influence of any mind altering substances… I made that mistake…)
Subj: Cams
From: Mike Williams <mike@wingworksusa.com>
Hi Monty, I have found a bad cam lobe on my 0-300-d. I have measured four other cams and found the absolute dimension from one side of the lobe to the other to be 1.486 on the d cam and 1.455 on all the other cams c-145 and 0-300b. My dry lash has been on the wide side. Do you know of longer pushrod part #’s? I will measure the lift on all the cams this am. Thanks, Mike Williams

The cams vary a lot on the O300’s — the p/n is 539803, but they have a suffix such as -AN, -AT or -AU and the earlier ones have more pointed lobes. The early cams, like what came in the C-145-2 develop good torque below 2500 rpm. The later cams develop more power at 2700 rpm. You can tell which cam is in an O-300 by simply running the engine and observing the manifold pressure guage. The early cam will idle at 600 rpm and about 10 inches of manifold pressure. The late cam will idle at 600 rpm and about 16 inches of manifold pressure, because of the increased valve overlap. TCM only lists P.030 pushrods for the O-300 in their parts catalogues. Fresno Airparts (3rd page of Trade-A-Plane) sells a P.070 pushrod. Longer pushrods are not too hard to make. Many old time mechanics and shops do this routinely. Use heat and remove one end of the pushrod. Select a steel washer the thickness you want to increase the length of the pushrod by. Put the washer in place and press the end back in the pushrod. With new valves and valve seats, you almost always need at least P.030 pushrods. With a reground cam, lifters, and rocker arms, P.030 just isn’t enough. I called TCM and pointed that out to them, they seemed unconcerned and suggested I replace the camshaft, lifter bodies and rocker arms! Nothing like spending a couple thousand bucks of someone else’s money! — Jim

ps… Remember, the rocker arm ratio is 1.2:1 (1 1/4″ : 1 1/2″) so if you have say, .130 clearance, (.020 over limit) You don’t need a .020 longer pushrod. You can figure it out, but the pushrod needs to be about .015 longer. Also, TCM says you can get by with more than .110 clearance these days with the new lifters, but they wouldn’t give me a number.

NO MORE SNAP-CRACKLE-POP… (100301)
From: Swift97B@aol.com
Subject: “Snap-Crackle-Pop”
While I was perusing Denis’ excellent website the other day, I toured the “Answer Man” area where I saw my discussion concerning the “snap-crackle-pop” I was getting from my O-300A last year. To complete the story — I (indeed) confirmed that it was an intake leak, like you were all telling me. I found that the previous mechanic had installed the exhaust pipes using “no blo” exhaust gaskets but did not grind them off where they hit the adjoining cylinder intake pipe. The bulging exhaust gasket eventually caused the intake gasket to leak. When I installed new cylinders recently I was careful to grind off the “no blo” gaskets to ensure they did not hit the adjoining intake gasket. Thanks for the help, guys.

HYDRAULIC LIFTERS… (100301)
Subject: Re: O-300A Hydraulic Lifters
From: Swift97B@aol.com
Hopefully, I can explain this while looking at the O-300 parts book. Recently, I had the occasion to pull out a pushrod from an O-300. The “Socket, Pushrod” P/N 637268 came out stuck to the end of the pushrod (by oil suction). It went back in easily. Is the “Socket, Pushrod” held inside the “Body, Hydraulic Lifter” P/N 530851 by the “Ring, Snap” 530940? Or, is the “Ring, Snap” used to hold the “Unit, Lifter Hydraulic” P/N 637269 in the “Body, Hydraulic Lifter”? Does the “Socket, Pushrod” just ride atop the “Unit, Lifter Hydraulic” without something holding it in (other than the tension of the pushrod and valve springs)? Thanks, Steve

Steve
The early engines did not use that snap ring to hold the lifter parts together. I believe the snap ring started with the O-300A, but these engines are now so old and have been overhauled so many times you might find the lifter bodies without the snap ring groove in any series O-300. You are right, the early engines just depend on the tension of the valve springs, thru the pushrods, to hold the lifter together. The snap ring has no function when the engine is assembled. It only prevents the “guts” of the lifter from being drawn out with the removal of a pushrod when a cylinder is being removed. — Jim

ENGINE TEMPS…(070302)
Subj: Engine Operating temperature
From: Bruce Ray (swiftfly@hotmail.com)
Monty,
This pertains to operating temperature on the C-145 0-300D engine. I have been noticing that the operating temperature has been running about 75 to 78 on my engine. The other day taxing out of Savannah I had several delays due to other traffic coming in. So they stopped us in place. I didn’t shut down the engine and the temperature creeped up to about 82-83. So then I shut down and let it cool for a bit and then took off and utilized a faster speed for climb and it cooled right off. But it seems to run right around 75-78. I know that is in the continuous use range but is there a way to bring it down just a little cooler? Thank you for your time. Bruce Ray N80644

Bruce
The max. oil temperature limit for a C-145 and all O-300s is 225F or 108C. So as you can see 82-83 is nothing to worry about. The cylinder head temp. limit is 525F or 275C. Don’t worry, be happy! — Jim

KARL THE STUD…(090302)
Subj: O-300A Cylinder Base Studs
From: Karl Johnason <karl.johanson@hs.utc.com>
Hi Jim,
After flying just a few hours with 78103 (with it O-300A 320 hrs TSO), we were getting ready to go up and observed rough running on the left mag during run up check. Pulled all the plugs and found the lower plugs to be fouled, particularly the number 1 and 2 cylinders. Also observed oil collecting in the carb heat box as well as fuel/oil residue in the carb throat. Looking into the cylinders we noticed that the number 1 and 2 were oil wetted as compared to the other four. Suspecting oil scraper rings and/or valve guides, made a decision to pull all six cylinders and have them overhauled. That’s now done and during re-installation we ran into a snag. The number 6 cylinder lower left 7/16″ stud would not hold torque. Also observed that this stud showed more threads than others indicating that it was not run in as far as others. This stud is one that goes in blind (as opposed to some of the others that go through to the cylinder bases on the opposite side) and bottoms out internally behind the fuel pump pad. Splitting the engine to install a helicoil is obviously one option but I suspect there are alternatives to try before going to that extreme. Any suggestions/procedures you might recommend would be greatly appreciated! Regards, Karl

Karl
Yes, that one stud is just threaded into the rt. crankcase half. They couldn’t make it a thru stud because of the proximity of the fuel pump. When I overhaul an O-300 anymore, I helicoil that stud as a precautionary measure. The O-300s are now 40 years old and the aluminum cases are getting tired! Having said that, there might be something you can do. You can drill the hole slightly deeper and tap it a little further. Then thread the stud in a little deeper. You may be able to get it in 1/4″ further. You might try locking it in with LockTite. Let it dry overnight and try torquing the stud. If it pulls out, you are committed to splitting the case and installing a HeliCoil. — Jim
PS — From my notes: The stud extends 5 – 5/16″ from the rt. crankcase parting surface normally.

KARL REPLIES…(090302)
Subject: RE: O-300A Cylinder Base Studs
Jim, Thanks for your help! Per your advice, first checked the remaining run-in. Was able to run it in 5 more threads (and still had adequate remaining threads showing on the stud, which also indicated that the stud was not all the way in to begin with) and hold the required torque. Will use the highest Locktite number 262 to insure that it will not budge! — Karl

OIL LEAK…(NOV 02)
Subj: Crankcase oil seal
From: Jack Gladish <jargladish@adams.net>
Hi Jim! Flew ol 21K yesterday, after words, I took of the rudder off to repair the rudder horn, has a bit of play in it.. The crankcase oil seal is leaking alittle, guess I’ll replace it while she’s down. Looked up the seal in my Cont. parts manual, but it didn’t list the #. My power plant is a 0-300D..Can you help? Also, it’s been a long time since I’ve done this, isn’t it pretty much R&R, with a careful cleaning of the crank, lubing the crank, but keeping the seal dry?? 2002 was a good year for my Swift, and me, thanks for all your help

Jack
My parts book has 539241 as the p/n for the front seal. I think you have the right idea as far as the changing procedure. If the seal persists in leaking, some fine sandpaper can be used, angle the sanding scratches to direct oil back to the engine. — Jim

 

IT ALL HANGS IN THE BALANCE… (JAN 03)
Subject: Re: Engine Balancing
From: Bud England <Dalswift1@aol.com>
Bought a pretty good digital scale and have started weighing rotating parts for the C145. I bought the “matched” set of pistons from ECI and was impressed to find them within a 3 gram range. Piston pins all identical down to the gram. Old reconditioned rods run from 727 grams up to 734. Can you, or anyone else, tell me where I can remove a tiny bit of material on the rods? I’m not expecting any variation in rod bolts and nuts (both new style), but will check them anyway. The car guys tell not to even bother weighing rings.

Bud
TCMs tolerance for piston weights is 1/4 ounce difference. (7 grams) So extending that figure to the rods 727 to 734 is 7 grams difference. The rod weight is reciprocating on the small end and rotating on the big end. Rod weights can only be lightened a gram or two by polishing off the forging flash at the center of the rod. Rather than grind off metal to get the rods the exact same weight, I pair opposing rods to try to get them exactly the same. i.e. 1&2 — 3&4 — 5&6. For example, if you have two rods weighing 727 grams use them in #1 and #2 position. If you have some that are several grams light match them with pistons that are several grams heavier. The big and little end can be checked by using a dead rest on your workbench and just weighing the one end at a time with the other end on the rest. If you can’t come up with a combination of weights with the rods and pistons you have, I would suggest you get some additional rods and/or pistons that are near equal weights. When I built up the engine for my Swift I had one piston that was a little heavy but the rest were all within 3 grams. I exchanged the heavy piston for one that was the same as the other 5 at the distributor where I had bought the cylinders (and pistons). Recently, I built up an O-300 using Superior Millennium Cylinders and all 6 pistons weighed exactly 725 grams. — Jim

BALANCE PART TWO… (JAN 03)
Subject: Re: Engine Balancing
From: Bud England <Dalswift1@aol.com>
Jim: Thnx for the info on balancing. Now I wonder if I could get you to go just a bit farther: You mentioned weighing the large end and the small end separately, using a dead-weight set up, but I didn’t understand what I was to do with this info, once weighing was complete. Also, there are a couple of things that kind of nag me: (1) It seems that the rod weight, WITHOUT THE CAP, is more important than the total weight of both, since this is the weight the crank is “throwing” into the cylinder, and (2) further, it seems top me that the weight of the small end is more critical than that of the large end, in that the large end has essentially become part of the mass of the crank, while the small end is is being thrown and pulled pulled back as part of the weght at the piston end. Does this make any sense at all? I’m sure it’s quite obvious that I’ve never tried to balance an engine before, so I need all the help I can get. You’ve given me a lot of help and advice the last few years. Believe me when I say how much I appreciate it. Bud

Bud
I don’t think you understood the dead-rest part. That is just a stack of wood or whatever to put one end of the rod on while weighing the other end. I have never weighed a rod without the cap and see no reason to do so. I have never given any thought to which end is the most important and would never get tied up in such detail! I learned about balancing from John Halling who had the first FAA Certified Balancing Shop. I balance every engine I put together and have never had a rough one since I started doing that so I must be doing it right! I mentioned not grinding metal off the rods to reduce weight. You can remove about 2 grams from the forging flash at the middle of the rod but you must be sure not to leave any scratches or other stress risers. The FAA prefers you shot peen the rods after any rework. That’s why I prefer to just match rods in pairs and get other rods if necessary. Remember I said the big end is rotating and the small end is reciprocating? I think that fits your statement in para. (2) above. I don’t agree one end is more important than the other just get ’em as close as you can, and don’t worry about 2 or 3 grams. Remember, TCMs tolerance is 7 grams. — Jim
p.s. The reason you weigh the ends of the rods is to make sure they aren’t grossly different. I once found on that had a casting (forging) irregularity and one end was way heavy. Most of the time you will find they are very close.

SWIFT MUFFLER REBUILD… (APRIL 03)
Subj: exhaust
From: Grahame Gibson <grim_downunder@hotmail.com>
Giday Jim, the right side muffler on my C-125 is requireing total rebuild. Was there a standard muffler used when the straight stack originals were not used. I assume a C-0300 system would have been incorperated. If you could assist me with the muffler part No. I may be able to track down a new unit or a quality used item, prior to persueing the rebuild option. 2nd question, the O ring that can be used to replace the metal spacer in the gear actuator, is that the same size as the O ring behind that spacer. I have not flow my swift since last August, family priorities overide all pleasures, all I have done is rotate the prop regually. Regards Grahame, swifter downunder.

Graham
If you take a look at the original Aircraft Specification (available on the Swift site) you will note Hanlon-Wilson Model 193 mufflers. These are specially made for the Swift airplane. A Cessna 170 version is not directly interchangeable, the exhaust pipe is canted inward below the muffler. The Cessna 172 version is bigger in diameter as well. Several Repair Stations in the US can repair these mufflers and I believe Hanlon-Wilson is still in business in Pennsylvania, USA. I doubt if there are any new mufflers available, but I did hear talk several years ago that Hanlon-Wilson was considering making some new ones, the price was high enough that I doubt if they sold any. There are used mufflers around and I have several myself. The ones I have need overhaul and I would not represent them as airworthy parts. I have installed two “O” rings instead of an “O” ring and the leather ring, I suppose another “O” ring instead of the steel ring would work Ok. Good luck to you. — Jim

DO IT YOURSELF HEAT MUFFS??? (APRIL 03)
Subj:exhaust heat shrouds
From:Grahame Gibson <grim_downunder@hotmail.com>
Giday Jim, I searched the web and found that Hanlon-Wilson were bought out some time ago by Wall Colmonoy Corp.,I emailed them without reply, probably to my advantage. Tony Green, the other Auatralian swift owner, has a set of the original pipes. If they are not in the best condition, I can have a set fabricated, using them as a template. NOW! I would like to sorce a set of heat shroud assemblies, item numbers from parts book, 7 and 14. I’m not familiar with this assembly, so if you can affirm this assumption as to parts book item numbers, please do so. These are not available with the pipes. So if you can help me in this area I would be most apprieciative, even a set that can be used as a template, as a mate is a wize at metal forming. This guy made a set of belly door frames after underbelly damage in ’95, and the with the doors that snuggly fit added speed to my swift. A servicable set of heat shrouds would be better by far.I’m going to duplicate this shroud search on the Swiftnews page set up by
Denis Arbeau. Regards Grahame.

Grahame
Making up a set of muffs may be your best idea.Yes, they are items 7 & 14 in the Parts Book. The reproductions wouldn’t have to be stamped out like the originals with their curved edges but made with flat sides riveted or screwed to a flanged end piece about 1 – 5/8″ wide. — Jim

REDUCTION IN MAINFOLD PRESSURE ON JUST REBUILT ENGINE… (MAY 03)
Subj: Manifold Pressure Question
From: Tom Yoder <tryoderjr@aol.com>
Hi Jim,
I have a quick question for you….any idea what might cause a reduction in manifold pressure…….I just rebuilt a C145 and installed it on N33TC…..everything on it is yellow tagged or new……including carb heat box/ filter/carb……Problem is that I am now only getting about 25.5/26″ MP and 2150 rpm static at sea level full throttle…..I have replaced a new Air Maze filter with a new Brackett…no difference…..MP gauge shows 29.5/30 before start so I know the gauge is at least close to right……the engine also seems to be running pretty rich…. Net result is a less than spectacular take off run and climbout…..have you heard any reports of misjetted carbs or anything else that might explain the restricted airflow ??….the only thing I haven’t done yet is swap out the carb with my old one and see if that helps…..one way or the other, I will see you at nationals and perhaps pick your brain some more. Respectfully…….Tom Yoder

Tom
I think I know what the problem is. The C-145 has a steel splitter above the carburetor in the oil sump. It is held in there with two rivets. If one or both rivets shear what you are experiencing will happen. Take off your carburetor and look up and see if the splitter is loose. If that is not the problem you should pull both intake manifolds and check for abnormalities. Then try another carburetor. If all of this doesn’t find anything I would suspect the cam to crank timing is mis-indexed. (wrong tooth engaged at the gear) I think the splitter is the most likely culprit. — Jim

ANOTHER IDEA ON TOM YODER’S LOW MANIFOLD PRESSURE PROBLEM… (JUNE 03)
From: Harvey Putsche <putsche@wt.net>
Subject: RE: May #4 GTS Internet Update
I had a problem similar to the one about the rebuilt carb. It was on a Navion E-225 PS-5 carb. When it was sent in for overhaul The mechanic did not specify what engine it was for and the shop flowed it for an 0-470 which it usually is mounted on. Trouble is it was mounted on an E225 and therefore was flowed too rich. When we had it flowed for the correct engine everything worked like it should. I would have the carb put on a flow bench and check it for proper flow for the engine it’s being used on. I only mention this because the symptoms he describe are so similar to what I experienced. Harvey Putsche

Harvey & Tom,
The thing is, there is no engine in the 145/0-300 family that is greatly different in flow rates or settings. However, that certainly doesn’t mean that the carburetor could be set wrong. The recent one piece venturi AD has caused all sorts of problems. For one thing, the casting on the three legs is very crude and may offer an additional restriction in the venturi area. I have taken a small file and dressed those legs down so they were more “streamlined”. If you don’t feel qualified to be working on your carburetor, I would return it to the overhauler. If you know someone who can work on it, I would say to lower the float level and file down those venturi legs. While the carb is apart check for proper part numbers as well as condition of parts. Are you still using that carburetor or did you leave your old carb on? Make sure the throttle valve opens fully, that the overhauler didn’t mis-index the butterfly on the shaft. — Jim

YOU CAN GET THERE FROM HERE…(JUNE 03)
Subj: O300-D accessory cover installation on O300-A in my Swift
From: Richard McLellon <richard.s.mclellon@lmco.com>
Jim,
I’m interested in pursuing a 337 to install an O300-D rear cover on my O300-A, to allow installation of a vacuum pump. I was talking to Charlie Nelson, yesterday, and he recalled that you had collected Continental documentation supporting such a change quite a few years back. Could you provide a copy of the information that would support such an alteration? I’m willing to do additional research, if necessary, but it would be helpful if I didn’t have to start from scratch. My O300-A doesn’t have that many hours on it, and I don’t want to swap engines. Charlie said quite a few people had installed O300-A cranks in O300-D’s, but he didn’t think very many had tried what I am proposing. Any help you could provide would be greatly appreciated. Best wishes, Steve McLellon

Steve
The short answer is, no you can’t do that. Actually, you can and it will work for a while, but the O-300D main case has an oil passage to lubricate the O-300D shaftgear. The O-300A case has no such passage. (the “D” bushing and the “A” pivot may have different dimensions too) TCM published a Service Bulletin some time ago to permit swapping of parts in a family of engines but unfortunately this is not permisssible in this case. It is permissible to swap crankshafts between a “A” and “D”. — Jim

SWAP C125 FOR O-300A… (JUNE 03)
Subj: 0300-A Engine
From: Bob Price <BobPriceSwift@aol.com>
I have located an 0-300-A Cont. Will it bolt up directly in place of the C-125-2 that is on the Swift? Thanks Jim for all your help! Bob Price 3361K

Bob
Yes, it is an easy replacement. Oh, there might be a few slight differences. The oil cooler fittings at the front of the case are a size smaller and some of the baffling may require trimming to fit the cyl. head fins. The mag “P” lead connections are different. Be sure to use new fuel and oil cooler hoses. The prop will bolt right up although it should be repitched to a 59″. — Jim

MORE ON THE SWAP C125 FOR O-300A DEAL… (JUNE 03)
Subj: 0300-A Engine
From: Bob Price <BobPriceSwift@aol.com>
Jim: Thank you so very much for your timely response…. with the 300-A can I expect an increase in performance? At this time I am operating out of a 3000 ft. paved strip…. I am indicating a climb rate of 500 FPM or less @ 85 to 90 MPH air speed….and a cruise of 125 MPH on an average…. I like MPH…that is how I was trained… The question… will the 300-A give me better take off performance and a higher cruise?…say 145 to 150 MPH? and maybe 700 feet per minute? As always… I am in appreciation of your expert guidace…. Bob Price 3361K

Bob
Like any thing else with a 50 yr old airplane “it depends”. I had a Swift (N2334B) that I could depend on 150 mph if I wanted to burn the fuel or 135 – 140 mph at 7.5 to 8 gph. Under optimum conditions it climbed 1000 fpm or better, hot and heavy it might have been under 500 fpm. My present Swift does about 140 mph at 24″x2600. — Jim

HOLD THE PRESSES!!! BOB’S ABOUT TO CHOOSE… (JUNE 03)
From: Bob Price <BobPriceSwift@aol.com>
Subj: 0300-A Engine / 0300-B Engine
Jim:
I am about to choose between a 300-A engine and a 300-B engine… will the 300-B engine bolt up as well as the 300-A? Also, I have a McCauley DM7357 prop on the 125 engine…will that prop work on the 300-A or 300-B? Can the 125 carburetor bolt up to the 300-B? Will either engine affect the weight and balance very much? also are these engines considered to be the ones with the heavy case? Thank you for your exceptional guidance…. Bob Price >>

Bob
The O-300B is the same as the O-300A except for the prop control valve at the left forward side of the case. If it has been operating with a fixed pitch prop it will have a 1-1/2″ plug in the crankshaft held in with snap ring. The Swift Assn. STC, SA1-326 for the O-300A formerly did not include the O-300B but it does now. The 1A170DM7357 prop will bolt right up, but should be repitched first to a 59″ pitch. Any prop shop can do this. The 125 carburetor (10-2848) will work but the 145 carburetor (10-4895 or 10-4439) is preferred. All O-300 engines are heavy case. According to the book, the 125 weighs 257 pounds and the 145 weighs 268 pounds. However the mags are lighter on the 145 so the net increase may be nil. — Jim

VACUUM PUMP ON EARLY O-300… (JULY 03)
Subj: vacuum pumps on cont. 145
From: Ray Brown <flswiftfixer@aol.com>
Jim, this is ray brown, down here in sunny, soggy fla. My fellow eaa member has a early B model Maule with an 0300 cont. I believe it is a A model. this stock model Maule has a belt/pully driven vacuum pump on the front of the engine. The V belt rides in a pulley mounted just aft on the prop. The pump in mounted like an alt. on a lyc. Has anyone tried to get this legal on a Swift? Maule in Georgia has the paperwork on it. I’m sure it is an aftermarket conversion. your thoughts on this please. Ray Brown

Ray
I never tried it myself, but I was told it won’t work in the Swift cowl. I wonder if it might work in a Corben cowl? I guess if I had one handy I would try it! — Jim

C-125 STUFF… (JULY 03)
Subj: Manifold Pressure
From: Bob Price <BobPriceSwift@aol.com>
Jim: Thanks again for the engine manual… It mentions manifold pressure but I could not find any specs in the manual…. @ 2450 RPM I am getting 26 plus inches… @ 2550 it gets into the 30 inch range! I have the 125 hp at this time… Also..do you have a 145 …300-A or B engine or do you have any leads where I could find one? Thanks Jim! Bob >>

Bob
The power charts are in the Operators Manual. The 125 performance chart is on Pg. 11. If you follow a line up 2450 rpm to where is crosses full throttle, you will see that is about 122 hp. 2550 at full throttle at sea level is 125 hp. That chart is somewhat confusing as far as rpm x mp is concerned. (wrong?) Better is the altitude chart on Pg. 16 which is for an O-300 but is close for a comparative readings. You may have to enlarge the chart to read it clearly. See where the rpm line intersects whatever manifold pressure you want to run then read the horsepower at the right. Unless you are located close to sea level you should not get close to a 30″ MP reading. Locally, (932 MSL) we get 27″ MP max. I don’t have any engines for sale. Just read the ads! — Jim

BOB FINDS AN ENGINE… (AUG 03)
Subj: 300-A
From: Bob Price <bobpriceswift@aol.com>
Jim:
I have located an 300-A 145 Cont. Will I need to purchase an STC for this installation or is there other paperwork that will be necessary? The 125 has an alternator conversion mounted to the rear of the engine near the mags. Will this bolt onto the 145 which still has a generator? You mentioned in earlier emails to have my prop repitched to 59:…. will this give me a better cruise or climb? Thanks Jim!……… Bob P

Bob
It well be necessary to buy STC SA1-326 from the Swift Museum Foundation. If you retain the alternator technically you should get a field approval for that. Is the alternator approved or just “on there”? The same alternator that fits a 125 fits a 145. Increasing pitch is like going up a gear on your car — it should go faster at the same rpm. Decreasing pitch is like driving in 2nd gear, it should accelerate better and climb better but not go as fast. — Jim

BOB WAS EXPECTING AN INCREASE… (AUG 03)
Subj: STC 300
From: Bob Price <BobPriceSwift@aol.com>
I just received the STC for the 300 engines… The STC indicates that there is no increase in the Max Take Off weight of 1710 Lbs. I was expecting an increase.. In your archives you mention the Swift can handle 1780 Max… How did you come by this? Thanks Jim… Bob Price

Bob,
There is a GW increase available from Merlyn Products to 1970 lb. for the big engine Swifts. They also have (had?) an increase to 1835 lb. for the 145 Swift. You would have to call Merlyn to see if that is available. STC SA1-326 does not include any GW increase and I’m sure I never indicated such. — Jim

O-300 OIL LEAK… (SEPT 03)
Subj: Oil Leak
From: Bruce Hubbard <brucehubb@cox.net>
I have a Cessna 172 with an 0-300 engine it has 450 hours on the engine. I’ve have been plagued with oil leaks. I had the engine resealed and the engine is still using one quart per 30 min. When I bought the plane it had 100 hours on the engine, but had not been flown for two years. do you think a top overhaul would solve my problem.

Bruce
I usually try to answer questions only for the Swift guys, but this may help some of them too so… It depends. It depends on what the mechanic that did your engine used for sealant on the various pieces. However, you should be able to seal up the leaks. If it is leaking at the case halves, clean it up well, then mask about 1/8″ each side of the split. Mix up some Pro-Seal or PR-1422 and brush it on the area of the crankcase split. If the cylinders are leaking at the upper end where the pushrod tubes exit the rocker box they can be reswaged. This requires removing the rocker covers, rocker arms and pushrods and using a special tool. If they are leaking at the other end replacing the rubber connectors require cylinder removal. If the sump gasket is leaking just tightening the 1/4″ nuts that hold the sump on may help. If the rocker gaskets are leaking they sell some replacement gaskets called “Real” gaskets which are a bright orange color. TCM has published a Service Letter on recommended sealants. Having said all this, your engine is using way to much oil. How is the general health of the engine as far as compression etc? Have you tried running the engine with less than 8 qt. of oil in it? The O-300’s are noted for throwing out the first quart of oil. If you are losing oil out the breather an oil separator such as STCed by M-20 Turbos may help. I doubt if leaks alone could account for 2 quarts an hour of oil usage. Perhaps your engine does need at least a top overhaul. — Jim

MICK IS FEELING THE PRESSURE… (SEPT 03)
Subject: Re: mp
From: Mick Supina <masupina@mmm.com>
I need to have you give me an education on manifold pressures. I really don’t understand it and would like to know more. Do you have anything written on the web site?

Mick
I don’t think there is anything basic on the site. Remember manifold vacuum from cars? Atmospheric pressure at sea level is 14.7 lb/sq/in. Manifold pressure measured in inches of mercury which is double that. I.E. standard sea level is 29.92. Normally aspirated engines normally read atmospheric pressure, less the losses in the carburetor, at full throttle. Supercharged engines can read 40 -60 inches depending on engine design. Some racing engines have used up to 100″. (until they blew up!) An O-300 at our airport (932 msl) will read about 26″ at full throttle. As you throttle back, or climb to a higher altitude, the manifold pressure reads less. A normally aspirated engine (non-supercharged) has a critical altitude above which the manifold pressure goes down below a desired reading even at full throttle. (usually 6,000 – 8,000 feet) A Swift with a stock cowl holds higher manifold pressure at a higher altitude than most airplanes because the carburetor is located in the higher pressure air of the cooling plenum with the updraft cowl. Generally, 23″ or 24″ of manifold pressure is desired for cruise flight. A fixed pitch prop must be matched to the engine and airplane to give the desired readings. A 75% power reading for an O-300 is 24″ x 2400 rpm. My prop turns 2550 rpm at 24″ which is maybe 80% power. If I want to use less power I must throttle back, the throttle is the only means of reducing power and rpm with a fixed pitch prop. Most engines idle with the manifold pressure guage needle at the bottom of the scale, about 10″. The later O-300’s have a lot of overlap on the cam and idle at 16″ due to induction losses due to the overlap. Any setting below 20″ is usually less than 50% power and not commonly used. On a Continental, carburetor heat is usually required below 18″ as these engines are prone to carburetor ice at reduced power settings. Horsepower is a cross section of rpm and manifold pressure. For example 24″ MP x 2400 rpm = 108 hp or 75% for an O-300. However 21″ MP x 2700 rpm also = 108 hp or 75% but you would need a different (lower pitched) prop to reach this figure. Don’t feel bad about needing manifold pressure explained. I am working on my third prop STC and some FAA engineers don’t understand it either! — Jim

PROP BOLTS…(JAN 04)
From: Todd Wilmar
Do the 0-300D’s have a 6 or 8 bolt flange? Thanks Todd

Todd
The O-300D has 6 bolts plus two pins that go in to the prop. (small flange) The C-145, O-300A & B have the big flange and 8 bolts. — Jim

HAPPINESS IS AN O-300…(JAN 04)
Subj: Swift Engines
From: Todd Asche <wcrcoi@midstate.tds.net>
Jim, I have found a C125 engine and prop (over hauled 150 hours ago) for 1500.00. The best that I have come up with for a 0300D ( SO FAR) is to build one up for about 10,000.00 plus the cost of a new prop. I am sure tempted to buy the 125 for the money?????? For the cost difference would I be that much happier with the 0300?? Thanks, Todd

Todd
I don’t know your finances but the O-300 is a much better engine than a C-125. When I got the Swift I have now in 1990, I first went “economy” and overhauled the 125. My friend, who is a CFI and I like to fly with weighs 300 lb. I was afraid to try and fly with him because the 125 just didn’t have any guts. I finally bit the bullet and bought a 145. All 125s are not as gutless as the one I had and if you want to get flying before you spend a lot of money go ahead with the 125. For the long run, you probably would be happier with the O-300D. — Jim

SLICK MAG ON C-125…(FEB 04)
Subj: mag conversion to Slick 6364 installation on the TCM C-125
From: Norm Clark <norm.clark3@verizon.net>
You guessed it. Our FSDO is balking at a field approval for this. He knows there has been a prior approval and wants us to find that approval so he doesn’t have to sign his name to the 337. Can you point us in the right direction? Thanks. Norm Clark

Norm
I have gotten those Slicks approved on a 125 via field approval. I can send you a copy of the 337 if necessary. I think Slick may have added the 125 to their STC by now. Harry Fenton used to work for Slick and he had a 125 Swift — but he quit there and has a new job. — Jim

DOWN DRAFT COOLING STC FOR THE O-300… (FEB 04)
Subj: STC down draft cooling 0-300
From: Dorothy Golding <dotgoldswift@mail.ev1.net>
Jim;
Duane needs to know if there is an STC for down draft cooling for the 0-300 engine. Stay warm. Dorothy

Dorothy
Yes, the Alturair STC for the fiberglass cowl and downdraft baffles. (SA68SO) In addition there have been one-time approvals for home made cowls and also for the stock cowl with a baffle to get the air to the top side of the cylinders. — Jim

SLICK MAGS ON A C-125… (FEB 04)
Subj: Slick mags on C125
From: Harry Fenton <gippsaero@charter.net>
Hi Jim,
I just read the last update and someone mentioned problems with getting the Slicks approved on a C125. I can help out with this problem as I have written a number of letter to support field approvals. I worked for Unison for nearly 20 years, and most FAA organizations will take my letter as supporting documentation. If anyone is having a problem with the FAA, just contact me at gippsaero@charter.net. The STC for the Slick 6364 mags was in the process of being updated to include the C125 before I left. One of the major delays is that we were going to use my ship for the conformity inspection, and I have been busy and the weather closed in for the winter. I’m in the process of obtaining my DAR for my new job with Gippsland Aeronautics, so I will probably be able to speed up helping Unison get this STC fixed this Spring. As a side note to mags, the smoothest running set that I have run on my C125 to date are the old SF6 Bendix “box” mags. Too bad they are so big and heavy as the engine runs noticeably smoother. One of the features of Slick mags is that the cam used on Slick mags is a “slapper” as opposed to a true cam (as used in Bendix mags) in which the points are in constant tension on a contoured surface. The Slick cam snaps the points open at the ignition point and drops away from the point spring which can cause the points to bounce. The slot in the end of the rotor shaft is critical to cam placement and if the slot is not centered in the shaft, then the timing of the cam to point opening varies slightly. As a result, the mag timing may vary slightly every 180 degrees which can yield slightly rough operation. One of the tricks that I would use to equalize this problem was to install the mag on a timing bench to find the “high lobe” of the cam. I would simply sand down the high lobe to equalize the lift on both sides. This can maybe be done on the engine, but with all of the gear train backlash, kind of hard to nail exactly. — Harry

EVEN ENGINES HAVE “ISSUES”…(MAR 04)
From: Swift31B@aol.com
Subject: Re: O-300
The engine in Janet’s Swift has “issues”. I’m trying to figure out my alternatives; whether to overhaul her C145 or just replace it with an O-300. Do you know of anyone who might have an overhauled or good low time O-300? Perhaps someone who has done a big engine conversion. I’m not quite ready to put an ad on the website just yet but I am asking around. Any advice you have on the best way to go would be appreciated. Regards. Alan

Alan & Janet,
There are only detail differences between a C-145-2 and an O-300A. For all practical purposes they are identical engines. For the record the differences are:

1. The cylinders on the C-145 have bronze bushings for the spark plugs. The O-300’s have heli-coils.
2. The pipe plugs at the forward end of the oil galleys are one size larger on the C-145
3. The C-145’s have Bendix SF-6-12 or S6LN-21 magnetos. The O-300’s have Bendix S6LN-21 or Slick Model 664 magnetos.
4. The later O-300’s have a superior oil seal for the starter clutch.
5. The later O-300’s have an alternator.
6. The C-145 has a splitter above the carburetor, in the oil sump, which is sheet steel, held in with two rivets. The O-300’s have the splitter cast in integral.
7. The carburetor is a Marvel Shebler 10-3237 for a C-145 and a 10-4895 for an O-300. The numbers may be different but the carburetors are for all practical purposes, identical.
8. The camshafts are all p/n 530803 but the later ones have suffix such as -AN, -AT or -AU. These camshafts seem to perform well at higher rpm, the earlier camshafts might perform better in climb. There were some cast iron camshafts before 1950 but I doubt any of these are around anymore. The C-125 used a cast iron camshaft. It is important not to use a cast lifter on a cast camshaft, they require a steel lifter. Also, a steel camshaft (p/n 530803) requires a cast lifter body. (p/n 530851)
9. The C-145 lifter bodies don’t have a circlip to hold the “guts” in the lifter, the O-300’s do. This has caused all sorts of grief to guys that pull a cylinder and break a lifter, necessitating splitting the case to replace the lifter.
10. The C-145’s have “wet studs” — the cylinder studs are installed in tapped holes that go into the case and thus possibly leak oil. The O-300 castings are revised so the studs are in blind holes and can’t possibly leak. (I have seen O-300’s made before 1960 with the C-145 style case)
11. All C-145 and O-300 engines with a “D” in the serial number have a dampened crankshaft. Continental made a few C-145’s in 1948 with undampened crankshafts, I doubt if any of these are still around.

Thats all I can think of right off, if I think of something else I will let you know! — Jim

SMALL CONTINENTAL ENGINE INFO…(MAR 04)
From: “Harry Fenton” <hlfenton@charter.net>
FYI, I have an archive of engine material for the small four cylinder Continentals that is also useful for the C125/C145/0300 series that you find interesting. Most of the information there is pretty good, but sometimes kind of rough in that it is kind of stream of thought answers (not unlike the stuff that has been archived from Jim’s comments). I will eventually have a dedicated website for the four and six cylinder Continentals, time permitting. You can find my archived engine page at: http://www.bowersflybaby.com/tech/engines.htm
Anyway, feel free to contact me any time and maybe we’ll meet at one of the fly-ins.
Best regards,
Harry Fenton
Gippsland Aeronautics
www.gippsaero.com

CAN YOU SAY “BOAT ANCHOR”???(APRIL 04)
Subj: C-125-2 available
From: Dave Stevens <DaveST@RP-L.com>
Jim,
I have a C-125-2 continental that originally was installed in a Swift. It is now flying in front of an EAA biplane. All logs go back to the test flights in 1948. It has about 2000 hrs total, 520 smoh. Do you think there is any demand for the original engine? Just wanted to know if many owners rebuild their Swift as stock, or if they all go for the bigger engines. Thanks!

Dave: The original 125 engines do not have much value — that is why they are often seen in homebuilts. The Swift is about the only airplane to ever use the C-125! The C-145 and O-300A are externally identical so they make a “bolt in” replacement and are a much better engine. Back when used cylinders were valuable I used to sell the 6 cylinders from a 125 and junk the rest. New cylinders are now readily available so now the cylinders are not worth much. I wouldn’t count on getting much more than $1000 for a good 125. If it has a “heavy case”, a little more. — Jim

CRANKSHAFT MODS…(APRIL 04)
From: BEWILLS@aol.com
The N number on my swift from the factory was NC78058, then changed to N78058 and finally changed to N599Z. The model number is GC-1B and serial number is 2058. It has the Cont. C145-2H motor and several mods including the stick mod. I am curious why the crankshaft was changed for a “A” model 300? I am guessing that it may have something to do with using an approved prop. Do you know if a vaccum pump can be mounted on the C145?

Terry
Changing the crankshaft to the “A” type permits the use of the 8 bolt props. (Sensenich 74DR and McCauley DM) That is no longer necessary because the revised STC SA1-326 permits the use of the Sensenich DC prop. My STC SA1490CH permits the replacing of the “D” crankshaft with the “A” type. A vacuum pump cannot be mounted on a C-145 in a Swift cowl. There is an STC for some airplanes to use a belt driven vacuum pump. The C-145-2H and the O-300A crankshaft take the same 8 bolt prop. The difference is the C-145-2H and O-300B have a different front main bearing and a hollow crankshaft with for provisions for a controllable prop. If a fixed pitch prop is installed on a C-145-2H or O-300B an aluminum plug with an “O” ring, held in with a snap ring, plugs the end of the crankshaft. — Jim

PAT IS HEADED FOR AN ENGINE TEARDOWN…(AUG 04)
Subj: Engine problems
From: Pat Waters <GPWATERS@aol.com>
I am writing to get some advise as to perhaps what is going on inside that big noisy power plant up front. Perhaps you could give me some direction or pass this on to another for their thoughts. I recently had my O-300 overhauled in AL and upon its return and instillation, I began the break-in, etc., as written in the manual and instructed by the mechanic. The first thing I noted is that all I could get on take off was 2100 RPMs with a redline of 2600 RPMs. I flew it far about 25 hours on mineral oil and then at the change had a filter added and off I went. At 32 hours TT on the engine, the oil was changed (annual) and the filter opened. In it was found some very fine gold looking metallic substances. The engine was flushed and refilled with mineral oil only to find after another hour of over the field, there was again gold colored (either brass or bronze) metallic materials found. I the last flight, I again noticed only 2100 RPM at take off and also noted that at about 3000 ft when I applied full power and tried to climb no greater than 700 ft per minute, the engine slowed down to about 2000 RPM and I could feel a strong shaking of the aircraft as if I were almost lugging the engine. Obviously, I have now grounded my Swift but am looking for answers if others have had this experience. The CT stayed at 90C and the oil pressure stayed at 30 to 35 psi. The plane is not a performer I know, but it seems that it is lacking the spunk of a good engine. Am I doing something wrong or just not used to that type of performance. I would be afraid to carry a passenger at this time (excluding the oil problem) as it just does not fell ‘up to the job.’ Thank you and your staff for your considerations and thoughts. Best, GP Waters

Pat,
If there is metal in the oil at 32 hours, it sounds like the engine should be torn down for inspection. Right off the top of my head the thrust washers are the most likely culprit. They are brass. With the spark plugs removed, does the engine turn freely? You mention CT of 90 C — don’t you mean oil temp? Do you have a cylinder head temp gauge? If it were not for the fact that you mentioned the metal in the oil, I would have you check the compression, timing and prop but I think the metal in the oil is the main thing. — Jim

PAT IS HEADED FOR AN ENGINE TEARDOWN PART DEUX… (AUG 04)
Subj: Engine problems
From: Pat Waters <GPWATERS@aol.com>
In the course of all this, a question has arisen in that I have an O-300B engine. There is an STC on this I suppose but how do I find it or is it your SA1490CH. I am not too sure but I am wondering if the removed engine sent for repair was the same returned, but anyway, I now have an O-300B and am told the carburetor is not correct which is why I have had so little power. As to the carburetor, it is 10-2848. Does that make sense?

Pat,
The original STC SA1-326 has been revised so the O-300B is legal. My STC SA1490CH is for the Sensenich 74DR-1 prop. There are several p/n’s which are Ok. The 10-2848 is a C-125 carburetor. It is not the approved carburetor for a C-145 or O-300. The approved carburetor is a 10-3237 or 10-4895. Actually that is not your problem because a 125 carburetor will work on the O-300 and the old version of the STC to install the O-300 in a Swift called for using the 125 carb! I believe they will accept a 10-2848 carburetor as a core on a new or remanufactured 10-4895 carburetor, they should, all the major parts are the same! I was thinking some more about your problem, the only bronze parts in the engine are the thrust washers, the rocker bushings, valve guides and small end connecting rod bushings. (not brass as I said earlier) I really hate to say it, but I’m afraid tearing the engine down is the best option. — Jim

STEVE ROTH RESPONDS TO PAT’S ENGINE WOES… (AUG 04)
From: Swift97B@aol.com
Subject: Pat Waters Engine Problems
When I installed new Millenium cylinders several years ago in my O-300, I had all of the rocker arms rebushed. I did no other changes to my engine. The first several oil changes showed lots of “gold” flecks in the oil. I flushed out the crank case each time and did normal oil/filter changes. It eventually cleared up. In my case, I believe the “gold” came from the rebushed rocker arms wearing in. The above would surely not result in the power loss you have. Regards, Steve Roth

NOT SO GOOD VIBRATIONS…(AUG 04)
Subj: A new vibration
From: Pat Waters <gpwaters@aol.com>
I feel like a pest, but am still in search of some answers. I am the fellow with the bronze/brass metallic residue in my O-300B engine which has 32 SMOH. In the course of discovery, it was noted that there was the 125hp carburetor on it and we have changed it to the 145 size (as per your thoughts). Now, when I run the engine up, at about 1200-1300 RPM there is a ‘chatter’ like vibration. It smoothes out above that but we feel it is unsafe. Have you or any of your associates experienced this. Could it be a broken engine mount? Could it be from within the engine? Could it be…? I’d appreciate some thought on the matter before we go any further. Thank you. GP Waters

Pat
A worse case scenario would be if a counterweight came off the crankshaft. The O-300 has two floating counterweights near the aft end. They are retained by pins which are locked in with snap rings. If a snap ring comes out, the counterweight can come off. It has happened more than once. At 1200 -1300 rpm the engine will be very rough. The way to find this is with the sump removed or one of the two rear cylinders removed. You might check for a broken valve spring or rocker arm first by removing the valve covers. — Jim

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