Lets see if I can explain this without confusing the whole planet . The single crank pulley is a rare creature . The offset of the single crank pulley is dependent upon the thickness of the balancer . This offset determines the alignment of the rest of the drive system . More common is a 2 pulley system ( the inner one drives the water pump and the outer one drives the power steering pump ). With this 2 pulley crank system the alternator from a motor with A/C will align perfectly and will align with the water pump , also . If your water pump aligns with your crank pulley you can have your alternator pulley unpressed the amount it takes to make your alignment perfect . Hope this helps, later.
