355 sbc

what makes a 350 sbc a 355 is it more then bore


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Nope just .030 over bored.

May be a dumb question but when you bore it .030", can you get away with using stock pistons and larger rings or do you have to use larger pistons as well? The reason I ask is the truck I bought has a 350 bored .030" over and i had a friend of a friend tell me the guy might have gone this route. Just trying to figure out what I'm working with without tearing it down.

ive heard of guys doing that ,boring 030 over and using standed bore pistons , with over rings , i wouldnt do that .

if you bore it .030" over then you use .030" over pistons... Its not rocket surgery.

It seemed pretty obvious to me too until somebody mentioned otherwise. Say they did just use over rings, what might be some tell-tale symptoms? Low, compression, burning oil, etc???

a bunch on piston slap

Slap... .005 can cause slap. This would be piston sacking you in the face with brass knuckles.

hahaha, X2, i agree i was being a little sarcastic

If it`s bored .030 and a standard piston was used it wouldn`t have enough compression to run. If it did the amount of slap on the bores would break the piston skirts in a hurry, and the excessive piston rock from such a loose fit would likely cause the piston to kiss the head. I love it when guys talk smack like this. We can prolly add him to the list of "350 rocket" and "3/4 cam"

add who to the list? And who was "talking smack"? I asked a legitimate question to get some clarification because it didn't sound right to me. I'm by no means an engine guru. Thanks for the info.

they are not talking about you, they are talking about the friend who said that he may have done that, or about some people who say you can do it. no one is attacking you bud, you did ask a legitimate question and you got a legitimate answer

Great answer!

Seriously to the OP and t-tung: Any time the cylinder is bored a out to a larger diameter, the piston will need to be exchanged for the appropriate size. i.e. .030 over bore diameter will need .030 oversize pistons.

If the cylinder is only honed out a maximum of a few thousands of an inch from the original bore diameter, then the original pistons can usually be used with new rings. Oftentimes, if it takes more than .005 inch to "clean up" the bore, it is adviseable to have the cylinder(s) bored out and oversize piston(s) installed.

To put these dimensions in perspective, the diameter of one hair on your head is approximately .003 inch.

Thanks Frisco.

MY87Z- after I reread it a few times I see who he was talking about. thanks for the help.

great posts guys. i was researching this exact question and found myself here on accident. had to join the site but....right on guys. 79 chevy with a 350/355 thanks again