Experience with Continental bottom past TBO

[Echo]

Wondering what brain trust thinks about running a Continental bottom past TBO?  IO-550-A 300HP.  Thanks for input.

[DonMuncy]

You almost never hear of a failure of the bottom end unless the case has been split for some reason. It would not bother me to run a long way past TBO, if you keep up with the warning signs. In this case, oil pressures. And on Continentals, the oil pressure is pretty low to start with, since the oil pressure pick-up point is much further away from the pump, compared to Lycomings. So, unless there was some abrupt change in the pressure readings, I would keep running it.

[kortopates]

Like Don said, monitor plus oil pressure is adjustable within limits and cam and lifter can be viewed without splitting the case or pulling cylinders, unlike most Lycomings.


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[A64Pilot]

Aircraft bottom ends are to some extent greatly overbuilt, a lot of that is due to operating RPM. 2700 or so RPM isn’t really that high an RPM for a crankshaft unless it has huge stroke and ours isn’t huge. Lycoming and Chevy big block have very similar strokes, yet the Chevy regularly turns twice the RPM.

However, rarely you do hear of a rod letting go and of course that’s sudden and catastrophic.

Usually for both engines it’s the valve rain that “makes metal” and or prop strikes that push an engine into overhaul. Prop strikes because if your already at or past TBO and the engine is being completely disassembled many decide to toss some of their own money in with the insurance money and overhaul.

The bottom end of an aircraft is so tough that no consideration is given to it in break-in, unlike almost every other engine where your supposed to baby it durning break in to break in the bottom end, with an aircraft the best way to break it in is to run it like you stole it. Of course that’s because the cylinders are difficult to break in, but it has no deleterious effect on the bottom end.

It’s not changing oil frequently that causes bottom end wear, if they are run with fresh oil they will go a very long time.

Edited July 22, 2023 by A64Pilot

[1980Mooney]

1 hour ago, A64Pilot said:

Aircraft bottom ends are to some extent greatly overbuilt, a lot of that is due to operating RPM. 2700 or so RPM isn’t really that high an RPM for a crankshaft unless it has huge stroke and ours isn’t huge. Lycoming and Chevy big block have very similar strokes, yet the Chevy regularly turns twice the RPM.

However, rarely you do hear of a rod letting go and of course that’s sudden and catastrophic.

Usually for both engines it’s the valve rain that “makes metal” and or prop strikes that push an engine into overhaul. Prop strikes because if your already at or past TBO and the engine is being completely disassembled many decide to toss some of their own money in with the insurance money and overhaul.

The bottom end of an aircraft is so tough that no consideration is given to it in break-in, unlike almost every other engine where your supposed to baby it durning break in to break in the bottom end, with an aircraft the best way to break it in is to run it like you stole it. Of course that’s because the cylinders are difficult to break in, but it has no deleterious effect on the bottom end.

It’s not changing oil frequently that causes bottom end wear, if they are run with fresh oil they will go a very long time.

The bottom end on that K that failed in Georgia in 2021 was caused by a missing cotter pin on the #4 connecting rod nut per NTSB.  Apparently after 28 years of operation since the last overhaul, the nut backed off while flying.

 

[Echo]

Great information.  Much appreciated everyone.

[Pinecone]

22 hours ago, A64Pilot said:

The bottom end of an aircraft is so tough that no consideration is given to it in break-in, unlike almost every other engine where your supposed to baby it durning break in to break in the bottom end, with an aircraft the best way to break it in is to run it like you stole it. Of course that’s because the cylinders are difficult to break in, but it has no deleterious effect on the bottom end.

Babying engines for break in is old school.

For high performance engines you run them several acceleration runs at full throttle, increasing the RPM each run, allowing some cool down in between each run.

BMW now breaks in their engines by running the rings/cylinder dry (NO oil) for a very short (seconds) run.  Seats the rings.  Then in the car, not over 5500 RPM or 104 MPH for the first 1200 miles.  But a lot of that is the trans and diff break in.

[A64Pilot]

41 minutes ago, Pinecone said:

Babying engines for break in is old school.

For high performance engines you run them several acceleration runs at full throttle, increasing the RPM each run, allowing some cool down in between each run.

BMW now breaks in their engines by running the rings/cylinder dry (NO oil) for a very short (seconds) run.  Seats the rings.  Then in the car, not over 5500 RPM or 104 MPH for the first 1200 miles.  But a lot of that is the trans and diff break in.

Old things are new again, actually burnishing in is very, very old school. The Model T engine was built so tight that it couldn’t run, so Ford hooked them to a huge electric motor and spun them without oil and burnished in the babbitt material that was used for the bearings, only then could it start and run on its own.

‘It was called “burning it in” they would spin it until the bearing caps smoked.

 

Edited July 23, 2023 by A64Pilot

[cliffy]

And the bearings themselves were hand poured Babbitt metal  

 

[DonMuncy]

Interesting. I was aware of the existence of them, but I had never seen it done. How long has it been since it was commonly done? 50 years?

[Fly Boomer]

18 hours ago, cliffy said:

And the bearings themselves were hand poured Babbitt metal  

So, when the Babbitt is poured, was there zero clearance initially, or was the “dummy” crank a few thousandths oversized to create some clearance when the crank was dropped in?

[A64Pilot]

5 hours ago, DonMuncy said:

Interesting. I was aware of the existence of them, but I had never seen it done. How long has it been since it was commonly done? 50 years?

It’s still done for the Model T engines at overhaul. 

Babbitt material as it gets old gets brittle and can fracture. Our engine is 100 years old and hasn’t ever been overhauled so I’m crossing my fingers. On model-T engines apparently they have shims under the rod and main bearing caps, when or if you get a rod knocking you pull over. pull the cap off of the oil pan to access that rod, there are four caps, remove the rod cap, remove some shim replace the caps and go on your way.

I’ve heard of leather being used for bearing material as a temporary fix.

The pistons are cast iron, there are two cast iron compression rings above the wrist pin, each a 1/4 inch wide, the oil control ring is on the piston skirt and it’s one piece cast iron also 1/4 inch wide. You have to see these rings to believe them, they are HUGE.

I think insert bearings first appeared in the early 1930’s, I know Packhard production in either 34 or 35 was full insert bearings, but I don’t know when even cheap cars did, I’d guess before WWII though as I assume they sped up the production process quite a bit.

I think the Model A had an oil pump, there were no pumps on the T, no oil pump, no water pump, but our 1923 Tourer has electric start, a gear driven generator and electric headlight, with if you can believe it, but high and low beams, 1915 in model T’s, older T’s have acetelene headlights, like old time miners lights. You drop a piece of carbide rock into water, it fizzes a little like alka seltzer but it’s acetelene gas, screw on the top and light the tube the gas is coming out.

It’s actually surprising how modern and well built a Model T is. I expected those God awful square nuts like you see on furniture, but everything is modern hex nuts and they are all SAE thread. It wasn’t until I think about 1916 when SAE thread became standard, until then there were different threads and of course that had to be a nightmare with different machines having different threads and nothing standard.

Edited July 24, 2023 by A64Pilot

[cliffy]

Ive heard some people shoved sawdust into the tranny to quiet it to sell it way back when.

[cliffy]

5 hours ago, DonMuncy said:

Interesting. I was aware of the existence of them, but I had never seen it done. How long has it been since it was commonly done? 50 years?

My Dad did it in the late 20s  Worked for the Ford dealer in downtown Los Angeles

[A64Pilot]

54 minutes ago, Fly Boomer said:

So, when the Babbitt is poured, was there zero clearance initially, or was the “dummy” crank a few thousandths oversized to create some clearance when the crank was dropped in?

Today they are scraped to fit, ideal is 1.5 thou on a T, often the bearing caps are shimmed to obtain clearance. Originally there was zero clearance, hence the factory hooking the motor up to a huge electric motor and burning in clearance, I think that was much faster than hand fitting each bearing, just burn it in. The production rate was phenomenal there were more than 15 million of the cars made and the engine stayed in production until WWII I think powering just about everything and Ford supplied replacement engines.

I have not found any part that’s not available for the Model T, even obscure interior parts. There are still thousands of them on the road

[A64Pilot]

Wife’s car, it’s actually unrestored, believe it or not but there wasn’t paint back then. The parts were either dipped in a type of linseed oil or “flow painted” where the linseed oil mix was flowed over the part it took quite a while to dry. Ours has tiny pimples in the “paint” It’s actually a type of Lacquer and is call Japanning 

https://en.wikipedia.org/wiki/Japanning

Many, many layers of this oil would dry over time leading to the invention of “Fordite” the first composite as far as I know. At least in 1923 the steering wheels wrre made from Fordite and ours at 100 years old looks as good as new with no cracks or chips

The top I don’t think is original, but I think the upholstery is, it’s not leather but believe it or not but they had a type of fake leather back then applied to a canvas like fabric.

[Fly Boomer]

26 minutes ago, A64Pilot said:

Wife’s car, it’s actually unrestored, believe it or not but there wasn’t paint back then. The parts were either dipped in a type of linseed oil or “flow painted” where the linseed oil mix was flowed over the part it took quite a while to dry. Ours has tiny pimples in the “paint” It’s actually a type of Lacquer and is call Japanning 

Gorgeous!  Can she drive it?

[A64Pilot]

59 minutes ago, Fly Boomer said:

Gorgeous!  Can she drive it?

No, for some strange  reason she just won’t. She’s not afraid of cars at all.

Car has been in her family since 1938, Her Great Uncle was one of the guys that started NAPA auto parts, before it had that name, but for some reason he collected original Model A’s and had several that he showed I guess in the 50’s or maybe 60’s or so, the thing was they were completely original, but in showroom condition

My Wife’s Father inherited them 25 or so years ago I guess and through bad business decisions “lost” them one after the other and the last one of two they sold.

I don’t know where this model T came from, same collection but it was the only T, but not running and I’m sure not showed. I think it came as some kind of deal when the Uncle bought the car he was after, but that’s a guess. I think it was just put aside and ignored.

Anyway I have every title of the car and it was obtained in 38 and I’m sure just sat since then under cover I’m thinking. Wife’s Mother in law tried to sell it but as it wasn’t running it didn’t sell, they aren’t worth much really and non runners don’t bring much at all, so when her Father passed my Wife inherited the car. Almost all T’s have been in my opinion over restored and modernized more than I think they should be, the car runs and operates beautifully in original form, no reason to modernize anything.

I know it hadn’t run in a very long time, the Carb was a mess, by that I mean for some reason the idle circuit had a brass plug in it and the carb needle and insert I guess it’s called were wrong so that even turned down to full lean it was no where near the jet, making the carb stupid rich, that’s why I think the idle circuit was plugged, some kind of shade tree attempt in leaning it out, but the car had no coils either. 

Valves leaked badly so I replaced them and reground the block, there are no seats just the cast iron block. Fixed the carb once I figured it out which wasn’t easy. Was surprised that it was an Holley carburetor,  and bought new overhauled coils, and the thing runs really very well. I know it sat since at least 38 and I suspect well before that and yet the bores were perfect no corrosion at all, it leaks oil of course they all do but it doesn’t burn a drop.

There is a lot of interesting Engineering about this thing and it’s far more advanced than I thought it would be. For instance every old car has a steering box bolted to the frame right? Not a Model T, the steering shaft goes to an arm, no box. The box is a planetary gear box the size of a tuna fish can directly under the steering wheel and has about a 4 to 1 reduction, much better I think than a big heavy steering box. The transmission is interesting, planetary gear set and bands like an automatic transmission, no clutch and no shifting gears, well it has a clutch, but you don’t use it in the normal sense, see if you can make sense of this, and remember this thing was designed and invented in the early 1900’s https://www.modeltcentral.com/transmission_animation.html

The Rear end is conventional modern differential with spider gears and everything, except it uses 600W oil. I didn’t think oil could be that thick, but it was apparently some kind of oil used in steam engines.

The thing has a magneto which is huge, the whole circumference of the flywheel, it has two functions, it’s a sort of oil pump and makes electric power for the ignition but it just makes power. The ignition itself is really ingenious, but best to read about it, it takes too long to explain, but I think in many ways that it was far ahead of its time and it had redundancy and was very simple and robust, very easy to fix in the side of the road where a distributor is not.

It’s very easy to drive once you sort of get used to three pedals with none being the clutch or gas. It’s my understanding in an emergency stop that you mash all three, that puts it into low gear, engages reverse which I assume adds braking force and puts on the brake, but it’s not going to stop in a hurry as only the rear wheels have any king of braking force, there are tiny brake drums with cast iron brake shoes, but they are the parking brake not service brakes.

Edited July 24, 2023 by A64Pilot

[Fly Boomer]

2 hours ago, A64Pilot said:

It’s very easy to drive once you sort of get used to three pedals with none being the clutch or gas. It’s my understanding in an emergency stop that you mash all three, that puts it into low gear, engages reverse which I assume adds braking force and puts on the brake, but it’s not going to stop in a hurry as only the rear wheels have any king of braking force, there are tiny brake drums with cast iron brake shoes, but they are the parking brake not service brakes.

This is why I asked if your wife could drive it.  My step father had one many decades ago, and I learned to drive it, but as I recall, way more complex than a clutch and gearbox.

[A64Pilot]

It’s different, but in my opinion not more complex, for those that don’t know and may be interested. others ignore the drift I guess.

There are three pedals, the left pedal if pushed down is low gear, if pressure is removed it comes up on its own and is high gear, in the middle is neutral. The big parking brake lever if pulled halfway puts the left pedal in neutral, pull it more and the parking brakes come on.

So with the parking brake on, start the car, release the brake by moving the lever half way, if you want reverse push the middle pedal, low gear the left pedal.

Once your going in low gear and want to shift to high, start letting up on the left pedal with the parking brake fully off, reduce gas to idle, let it slip into high gear, add gas.

There are no “gears” what’s going on with the pedals is your tightening cotton or wood bands around a drum exactly like an automatic transmission bands do. There is no positive indication of neutral though so that takes a little getting used to. I just pull the parking brake some if I’m having to stop at a light or something

Once you get just a little used to it, it’s quite intuitive and for instance you can back up and turn and go forward much quicker than you can with a stick shift car, ever driven a lawnmower with one pedal for forward and another for reverse? It’s like that.

They did everything with and to T’s, made tractors out of them, used them to drive sawmills etc and it was I think maybe the first snowmobile, the USPS and Rural Dr’s used them in the great white north to get around when not much else could.

https://www.blueovaltrucks.com/ford_articles/ford-model-t-snowmobile/