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Ok guys here is the guestion. I'm putting a 302/C6 in my 60 F100. And to get everything to work I had to put a very small pulley on the water pump. It is know about 20% overdriven. My question is well this hurt the pump? I know you can get overdrive pulleys for engines but the most I've seen have been only 10%.
As a rule of thumb, the w/p pulley should close in diameter to
the crank pulley. Ford has used ratio from .9 all the way to 1.25 for different applications. Yours would be called 1.2 ratio if it is about 20% smaller then the crank. The only risk is the faster pump impeller could cause pump cavitation at high engine rpm. If you experience any overhead condtions, this could be a contributor.
I read that later model vehicle's water pumps were usually overdriven especially when they had A/C to help in cooling. But a guy I work with brought up a good point too. Most of these later model applications had a clutch fan. If you put a solid or flex fan on your motor, you might get excessive fan noise and drag from it being overdriven.