Maximum bore size on smaller hemis?

centerline · Post by **centerline** » Mon Apr 21, 2003 9:38 am

+.090 is probably safe but before you go past +.060 (especially with the 345 since it's just a bored out 341) have the block sonic checked. You can never tell if the mold shifted in the casting process and if it did you could ruin a good block in a heart beat. Although 95% of early 331's can be bored to 354 my '54 block had shifted just enough to make (+.120) too risky. I eventually went with a set of very old but brand new cast +.060 J&E's with stock 8.5 compression and I'm very glad I did.

Post by **scottm** » Mon May 12, 2003 8:25 pm

The bore change between 331 and 354 is 0.125 in.
I have been asked by someone if a 331 can bore to
a size enough to use 354+0.060 overbore pistons?

TrWaters · Post by **TrWaters** » Tue May 13, 2003 5:37 pm

As stated, the only sure way is to have the block sonic tested.I definately would have a 331 car block tested before boring to 4".
The later 331 truck blocks that I have had appear to have very thick walls. In fact, the 354 truck motors used the 331 block castings.
I am currently building a low deck stroker, using a 331 truck block bored to 4".