SmirchIs#1

I'm hoping someone can tell me what is max bore oversize on the 455.I have a 69' 455 that I thought was +.030,but when I showed it to a guy that was interested,I noticed .060 on the piston.The bores were not damaged when put in storage 10 years ago.As you can imagine the bores are somewhat rusty.If they don't clean up with honing,can it go to +.070 ? Thanks for any input

OLDSter Ralph

It depends how deep the rust and pits are, if they can be honed. The problem is going to get a set of pistons and rings. They most likely will be "special", and will cost more.

Chesrown 67 OAI

ask cutlassefi (Mark Remmell) . he will know how large of pistons you can buy without special order.

cutlassefi

4.190-4.195 are the next sizes. But you’ll either need to use a Pontiac piston and a different rod with those sizes, or get a special piston to use with your stock length rod.

Chesrown 67 OAI

use that .060 over block for a boat anchor and get a block that can clean bore to .030 or .060.
that would be least costly approach!