MONTY THE ANSWER MAN ARCHIVE

CONTINENTAL O-300 INFO Page Five...


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



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