Hi all, I am putting AC on my 1970 cutlass and have assembeld all the parts for under the hood. I notice that the water pump pulley with the 3 grooves for the AC cars is a smaller diameter than the 2 groove on my non AC car.Does anyone know the reason for this?

Thanks

 

My guess is so the pump spins faster, in case of a high performance application.

I'm interested in buying your non/ac pulley, if it's for sale.
I have a big giant 3 groove pulley on my race motor right now, and it looks stupid with no A/c or power steering.

 

The reason for varying the sizes of the pulleys of course is to obtain the desired drive ratio between the drive unit [the crank] and the driven units- coolant pump, PS pump, alternator, etc. Generally, the AC cars had a thicker radiator, perhaps a different WP impeller, and more heat to get rid of. It's all a delicately engineered balancing act, with lots of time put into selecting all the right matched pieces.

Oh, I too am interested in a 2groove WP pulley, and very intere$$$ted if it'$ $tamped "KA"

 

Hey Scott:
Page 92 Section 6-1 of the Assembly manual gives you the pulley, belt, and generator requirements. The diagrammes show the different Crank and Water Pump pulleys - a setup which drives the water pump at a much greater rate for any given engine speed.