Cylinder Head Runner Volumes

[RJ]

Originally Posted by Rod Greene

When NHRA poured heads for SS They didn't take into account different valves. On my 72 340 stock heads with flat valves the cc's are bigger than spec with the tulip valve they are smaller. I talked with Bruce about this a few years ago. I would have to fill a stock port to make them meet the spec. I have 20 sets of stock unmolested 340 heads

Another one Rod is the 894 casting 2.020" valve 340 head, how does that pour 2 c.c.'s LESS than the 587 casting 1.880" valve 360 head with the same port geometry?