318 head flow

Nice 308 head with factory valve and valve job(valve seat not beat up or sunk):
4.00 bore, 3/4” radius plate:

A- stock head and valve/valve job
B- grind/narrow seat, back cut valve, minor bowl blend

Lift———A/B
.100— 51.6/ 58.8
.150— 75.2/ 90.0
.200—107.9/127.0
.250—137.1/157.4
.300—163.0/183.3
.350—180.8/199.3
.400—192.2/206.2
.450—201.9/208.2
.500—206.2/209.5
.550—207.5/210.8
.600—207.1/210.0


Sure........ compared to the previous post, it’s a different head, on a different bench, with a different radius entry.
Compare at your own risk !!

A 20cfm gain through the bulk of the lift curve, nice gains for minimal easy work. The benefits of a good valve job and valves are often overlooked.

The differences in our 308 flow tests for the reasons you mention, drive home the point I try to tell people all the time.