Porting 302's

That was with the 302s. I haven’t measured the chamber volume of the 163s, but the set I got looks like they’ve been resurfaced and are probably in the 66 cc range. There are differences in how much cut it takes to remove one cc from an open chamber vs a closed chamber. My source shows .0053 cut / CC for a closed chamber and .0048 cut/CC for open chamber heads. Both heads show .0095 head intake flange cut for each .010 of deck cut for proper intake fitment.