[KJL]

Powermaster web site recommends a driven to drive pulley ratio of 3:1. The crank pulley outside to outside is approx. 7.125" and the stock pulley is 2.875", this yields about a 2.5 ratio. The new pulley measures in at approx 2.125" which yields 3.35 ratio. Powermaster says you can't overdrive an alternator but you can underdrive. They recommend staying above 2400 rotor rpm at idle speed. If I idle at 900 rpm that will put me at 2250 rotor speed. I may test fit the existing pulley to see if there is enough tension in the belt. Plus I am not 100% sure if the alternator that is in the car is the stock unit. Anyone know what the stock pulley diameter should be?

Please note these dimensions are to the outside lip. They are approx the same and for calulating ratios, it shouldn't matter.