thanks for the information.
When I plugged in the 1.77" compression height, I got the following CR values...
Stock 318 block with 302 heads (62.6cc) with 0.080" gasket and = 8.56:1
Stock 318 block with 340 "X" heads (71cc) and 0.020" think gasket = 8.55:1
Stock 318 block with 340 "X" heads (71cc) decked and 0.020" think gasket = 9.3:1
Does this coincide with popular wisdom, because it makes no sense for me NOT to use the X heads on my 318. I ran several cam scenarios through CamQuest6 and everything tells me to use them. I even bored the 318 0.050" and the hp barely budged, so it makes no sense for me to go that route.
I should have a screamer in the 5K rpm range, with only heads, cam, intake, headers and carb. All I need is a cam.
Any experiences out there to the contrary?