head shaving specs??

[struckinc]

i am ablout to start building my motor. na/ka. and i just left the machine shop. i have a question about shaving the head. i was going to shave the head down as much as i can without having interference issues. i am going with a cometic .040 metal headgasket. my question was how much do i need to shave the head down before i run into valves meeting pistons. and how much of a gain will i get from that. would that make abig difference performance wise? i am already going with 10.5 pistons so how much would the head work change the compression?

[180fan]

doing the shave will increase compression slightly. generally, the less you shave the better off you are. The issue you'll see first before pistons hitting valves is your cam being off a few degrees even though you believe you're at proper timing. It will not make much difference in performance. Look to build compression other ways.