After modifying the separator plate as directed, I tried three pulley combinations.
1) 6.75" upper pulley, 8" lower. Result, cool as can be, never over 160*, fan noise and drag horrendous. 18.5% OD
2) 7.25" lower pulley, 8" upper pulley. Result, motor warms up to ~190* at idle, low speed, but cools to about 160-170 at 50MPH Fan very quiet. Pre-ignition when at full throttle. 10.3% underdrive
3) 7.25" pulley lower, 6.75" upper. Result, a little fan noise (more than I'd like), but stays at 160* all the time. No pre-ignition. 7.4% OD
It all makes a difference.
1971 GTO
462, 7K3 heads
Summit 2802 cam
iron intake, 800 Q-Jet
headers, stock exhaust
T400/10" converter
3.90 rear
3750 w/o driver
19" factory seven blade flex fan, Olds shroud 4-row factory radiator
No air
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