Small Block Head Flow Chart
SM Head...... ootb vs reworked valve seats(with very small back cut on both valves) and minor bowl blend......
4.00 bore, 28” test pressure, no tube on exhaust.
A-ootb
B-reworked
Intake-
Lift———A/B
.100— 61/65
.200— 120/126
.300— 177/180
.400— 221/230
.450— 231/246
.500— 240/256
.550— 250/267
.600— 250/262
.650— 251/261
.700— 253/261
Exhaust-
Lift———A/B
.100— 49/50
.200— 97/101
.300— 134/139
.400— 154/169
.450— 160/174
.500— 164/178
.550— 166/179
.600— 168/180
.650— 168/181
.700— 168/182
It’s a decent gain considering it’s maybe a 1cc increase in runner volume.
SM Head...... ootb vs reworked valve seats(with very small back cut on both valves) and minor bowl blend......
4.00 bore, 28” test pressure, no tube on exhaust.
A-ootb
B-reworked
Intake-
Lift———A/B
.100— 61/65
.200— 120/126
.300— 177/180
.400— 221/230
.450— 231/246
.500— 240/256
.550— 250/267
.600— 250/262
.650— 251/261
.700— 253/261
Exhaust-
Lift———A/B
.100— 49/50
.200— 97/101
.300— 134/139
.400— 154/169
.450— 160/174
.500— 164/178
.550— 166/179
.600— 168/180
.650— 168/181
.700— 168/182
It’s a decent gain considering it’s maybe a 1cc increase in runner volume.