max overbore and still seal the head

I have a dart big m bbc. What would you say would be the max bore size? And still have enough meat between the cylinders to keep the head gaskets sealed. I have figure eight o-rings. Dart said the max would be 4.600 with 40 psi boost. They were not sure if there was enough to keep the gaskets in place thanks Craig

 

Big M

I have the same block and I was going to go with the 565 CID, but I didn't like how little material was left between the bores. I decided to stay with a 4.5 bore and build a 540CID. Plus with blown alcohol its nice to have the extra bore material for cleanups if needed.

My 2 Cents

Corey

 

4.60 is a good place to stop. If you need any bore clean-ups just hone a couple thousands and order pistons to size. The file fit rings for a 4.600 bore will work up to about 4.609.

When the block gives up think seriously about upgrading to the New Century Performance aluminum block. By the time you purchase a new steel block and have all the machine work done your within reach of the upgrade.

Been there done that...........blessings..........Ron Clevenger.