I have 2 crank pulleys one is 6 1/8" and the other is 6 9/16" which one should I run for best performance??? Don
Depends on what you want the waterpump pulley to do, you want it to run slower or faster ? As far as HP gains, you're not going to see any gains in the "seat of the pants meter" whichever one you run. The larger the waterpump pulley is in relation to the crank pulley, the slower it's going to turn the pump, which theoretically nets you more power, but often at the expense of cooling capacity as the volume of coolant moved by a slower pump will be less, hence less cooling.
So basically, just use the bigger one since there won't be a difference in HP and there WILL be a difference in cooling.
Yes, that's what I did. I have two different pump pulleys that I can use on mine, I've run both and the seat of the pants meter registered no difference. I prefer to have all the cooling capacity I can get.
