Sgruenauer96

Opened up my shining example of a awesome purchase to find one of the pistons on my 350 cracked in 2, and scored up the cylinder wall pretty well. It definitely won't hone out. The motor is a 72 350, I'm currently waiting on some calls back on prices, but even with price, I'm not sure if I want to sleeve it or bore it out. I'm no engine master, I pick **** up as I go. Looks to me like these are sleeved already so wouldn't I be able to get a sleeve and reserve it or would the shop have to bore it put a bunch and put a sleeve in? I'm going to put flat top pistons in after it's all set regardless of which way I go. So I guess I'm looking to see if there's a negative side to either option. To me I'd kinda rather stay stock size if possible just for longer life out of the motor, but if sleeving it has downsides like that I'm not sure which way is better/safer.

Olds64

Have a machinist check the block. They'll be able to tell you how to remove the scoring on the cylinder.
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redoldsman

If you are replacing all the pistons, I would probably rebore it. At this point most of the cylinders are out of round. Some of the experts will speak up.

fleming442

I'm no expert and I don't know your intentions or budget, but bore it with new pistons. There's no replacement for displacement!

OLDSter Ralph

From your other post.

I think you should find a good shop and a good machinist, familiar with an OLDSMOBILE engine. You seem to think this block has been sleeved already. I get a feeling you are inexperienced and are guessing about things. The depth of the score mark in one cylinder is going to be a determining factor as to what needs to be done.
....Just my two cents worth.

joe_padavano

X2 on what Ralph said. There is no issue at all going even 0.060 over on a 68-76 Olds 350. If this is a newer 350 with windowed mains and a lightweight casting, that might be a problem.

Fun71

I do not know where you got this idea, but it is not accurate. Boring a block and using oversize pistons will not reduce the life expectancy of the engine.

olds 307 and 403

Olds V8's went high mileage for their time without needing a rebuild. With a modern 1mm ring pack like the Mahle along with being coated, they should last hundreds of thousands of miles before being worn out.

BangScreech4-4-2

I'm guessing OP is talking about leaving more meat in the block for future rebuilds/overbores.

Not that it's likely to be a problem in any of our remaining lifespans.

BillK

Not sure what gives you that idea ? Definitely not sleeved originally. The rest of the block needs boring anyway so just get it to the machine shop. Tell them to start with the messed up cylinder and see what it takes to clean it up. Then do the rest of them the same.

Sgruenauer96

it wasn't sleeved, just some leftovers from the gasket, I scraped it clean and saw its solid. Didn't have much more than a quick check before I stopped working on it. Probably gonna go with a sleeve if the cylinder aren't worn. But there's crosshatching still showing on all the other cylinders. The rest looks fantastic. But when I have my buddy with a micrometer come by we'll measure and see what everything is at and make a game plan from there.

Sgruenauer96

5-10 cc's aint much gains. If i was going for displacement I'd have gotten a big block.

joe_padavano

At 0.030" over you get a 355. At 0.060" over you get a 360. In any case, it's ridiculous to not install new pistons during a rebuild, and frankly sleeving with a new piston will likely not be much less expensive than a traditional bore and eight pistons. Keep in mind that installing a sleeve requires boring that cylinder significantly oversize anyway and likely means you can never re-bore. You really are doing this the hard way for zero gain.

olds 307 and 403

The issue is the factory 24cc pistons which sit .025" to .030" below deck. It will take a lot of milling and decking to hit even 9 to 1 to compression, kind of your minimum. My cylinders looked good and a couple would not clean up to the hone only size of 4.065", so a .008" oversize Mahle also offers, almost forgot about that one. CP also offers forged 3 cc pistons in that size. The Mahle are 10.2cc dish forged and are taller as well, sit less than .020" below deck. I got my deck cut .016" and pistons are .002" or .003" below deck, very close to zero. The ancient Speedpro forged 6cc and flat top pistons are about the same as factory pistons below deck, .025", I believe.

cutlassefi

AND once they drive in the sleeve, it’ll knock the adjoining cyls out of round. Lose-lose.

brownbomber77

You're overthinking this. I'm sure it's fun to drive but you really gonna drive this thing 150,000 miles from now? Slap some new pistons in and run it. Or snag another block if you're really concerned this one won't make it. Very rare to get a block 50 years old that won't need an overbore. I might just be lucky but I find 1972 and older 330 and 350 engines on marketplace in south Florida for less than $500 regularly. Not running outta stock cores anytime soon. The one you have is probably fine for just an overbore. Machinist would start with that bore with the piston you choose anyway. Guy just needs to know what sizes are available at the time machining starts so IF that bore doesn't clean up at .030, there's still another size available.