chevy 355 ( egg shaped )
Help,I bought a chevy s-10,with a 355 down in it.It's a strong engine,doesnt smoke and there's no noise in the motor,The guy I bought it off from told a freind of mine that the cyclinders are egg shaped.My questions are is this possible and how does egg shaing of cyclinders happen and can this be fixed or do I need a new motor?
Tom, I'm pretty sure that the previous owner means simply that the cylinders are "out of round." There's a few reasons for this, but it means that the cylinders are not perfectly round, so the rings will not seal well, and will do things like burn oil, leak down during the compression stroke, and so forth.
It may not have been properly bored, or the boring was done badly, or it could have warped over time due to something like overheating.
There's no solution other than reboring the engine. The block can be saved if there's enough thickness in the cylinder walls to accomodate a re-boring from a machine shop. If it's a 350 block bored out to 355, then there should be plenty of thickness. What you have to do to correct this is rebuild the engine, and be sure to have it sonic tested to see the thickness of the cylinder walls. If they are thick enough, you can rebore, but if not, then you know you need another block.
If there's no problem with the way the engine runs, or if the problems aren't bad enough to make you want to rebuild the engine, then your engine is fine for right now. No smoke, no noise, no loss of power, then in all no real problem. There's probably a lot of "egg-shaped" cylinders out there that people may not know they have. Again, the "egg-shaped" condition just means that the cylinders aren't as round as they could be. Keep in mind that things won't get better though, only worsen over time.
Also keep in mind, there is no perfectly round cylinder. Even when a engine is honed with a head plate installed althought it does get it close. For a cylinder to be perfectly round there needs to be a even amount of metal around the cylinder, and in every small block that rolled off the line, none of them are, they will always be thicker or thinner on one side or the other due to core shift and the like. So when the engine is run and gets up to temp the cylinder is out of round, although like I said, it`s close. Some builders heat the block while honing the block with the head plate to simulate running conditions, and this will get it even closer. There has to be thousands of small blocks out there with out of round cylinders that were just honed with a hand hone. As long as the engine doesn`t have a excessive amount of blow by, I wouldn`t worry about it.
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