BBC--Piston wall scoured--am I screwed?

[Bandit]

OK so I have my engine, a 402 Chevy big block, apart for the 4th time in 3 years, this time due to head gaskets that weren't sealing right. Now we see there is one cylinder wall that has a big scratch from top to bottom. Not exactly sure yet what caused it, but it is deep enough to hook with a fingernail.

The engine is at the machine shop right now so they can test whether the cylinders can be honed and my old pistons reused. They seem to think that we can just overbore the block again and get a new set of oversize pistons. However I don't believe my block can be bored any larger. The engine has been bored before, the current bore is 4.1550. From the data I have found online, this bore size means my block is already bored .60 over, which I believe is the maximum bore for a 396 BBC. Can anyone verify this for me?

If the cylinders cannot be overbored any larger, I will be hunting for a new block. This puts me in a quandary since I am in Italy right now. There are some Chevy engines available here, believe it or not, but of course they are very hard to come by. I have Italians working on my engine at the machine shop, not sure if they even know what can and can't be done with this block...so it would be great if someone can tell me what my options might be before I spend money for machine work on this block.

[EFI69Cam]

worst case you would have to sleeve that hole.

Does the scratch correspond with a ring gap? Who filed the rings?

[MonzaRacer]

402s can be bored and use a 060 402 piston too. I have 6 030 402 pistons and 2 060 396 pistons in my 402.
If they can take .100 out of 454s why not use the 060 402 piston (they dont list an 040 the last time I looked.
Good luck and if it is a gonner just get you a 454 block and build a 427 all you would need is new pistons and rings! and 427s are sexy too.

[Bandit]

402s can be bored and use a 060 402 piston too. I have 6 030 402 pistons and 2 060 396 pistons in my 402.
If they can take .100 out of 454s why not use the 060 402 piston (they dont list an 040 the last time I looked.
Good luck and if it is a gonner just get you a 454 block and build a 427 all you would need is new pistons and rings! and 427s are sexy too.
Could I overbore just that one cylinder and put in an oversized piston? Or would I have to replace 6 of them like your engine, to balance it out? I see that Summit has 4.185" pistons for the 402. It would be nice if I didn't have to buy 8 of them.

About building a 427 from a 454 block: Are you saying I could use the crank, rods and all the other parts from my 396 to build a 427? That would make it worth my while to find a 454 block and buy all new pistons!

Please bear with me, engines are not my specialty...

Maybe I could just find a wrecked Ferrari since I am in Italy, and throw the engine in my car...ok well maybe not...:rolleyes:

[Adam's 55 Chevy]

With a check for core shift a 396 can be bored + .125. If the scratch is too deep to ignore sleeve that one cylinder and rebore it to your current size. I would not use differing piston sizes in the same engine at all. I have not heard of any reputable machine shop advocate that practice. Failing that there is a 4 bolt main stock bore 454ci block on ebay UK at the moment.

[Skip Fix]

They should be able to sonic check that hole and see if it is safe to go bigger.

[pav8427]

Be cautious if you sleeve just one hole. The adjacent bores will distort when you press the sleeve in. Yes the 454 block will get you a 427 using all your internals and 427 pistons. If you end up hunting down a block, don't forget to check the casting # and make sure you get a standard deck block, not a tall deck truck block.