Cylinder Heads 101

Great info. I would be really interested in the 516 big block heads as compared to the other stock heads. I have a 383 with .570" roller cam and the heads are basically stock with 1.74 exh valves put in place of the smaller 1.60's. I was going to try some porting on them but have other things to do this year, (like build a new car, .lol)

Anyway, thanks for all the info.