wildcobrar

There is not any way to give you an exact number on the max lift you can run. Piston to valve clearance must always be verified. I use a KB Hyperutectic #148 piston in mine with 255/261@.050 and my Gross lift is .659 and .667 with no piston to valve clearnace issues. The open chamber 4V heads are an upgrade to the 2V open chamber heads. They have bigger ports(4V) and both 2V and 4V have the same chambers.(76cc) With KB 177 flat tops you will gain more compression and help the Quench because they have a 1.670" compression height vs. stock 351C 1.647" compression height. Also, these pistons have a little deeper valve relief than the stock piston. If you are doing a mild rebuild with a mild cam the factory short block will be fine.

Joe