There is a guy in the local paper with a '68 302 block that has been bored .060" with pistons, rods etc for sale. Is .060" over bore too much? Would I be asking for trouble?

Thanks

 

if it ever got hot it would be a done motor thats for sure. also that says 1 of 2 things, either that motor has been rebuilt many times or it had a major cylinder issue which required it to be bored out that much. 302 blocks are plentyful so i would pass this one up in my mind. I have 2 that are stock but live a bit far unless you payed shipping

 

.040 is considered the max safe overbore on these blocks. Some people have found that by sonically checking the block for core shift they can go to .060 but your cylinder walls are very thin by that point. I agree with Kemical, these blocks are so common that it's not worth the risk.

 

I had a late 80's roller block split a wall with a .040 overbore. Some get lucky with 60, some don't. The Mexican and late 70's D8VE blocks got thicker walls than the others.

 

Yes, but I've never heard of a '68 block punched out .060 over before. Those cylinders must be perfectly centered, and even so I'll bet they're paper thin. They probably flex from the pressure of the rings passing over them!