Pulleys!!!

[steved]

what's the "correct" setup for pulleys on a big block gtx with PS and AC???

Crank pulleys, I have 2. 3 groove and 4 groove, diameters of just over 7".

water pump pulley is single groove and 6 1/4" needless to say, they hit. talking with the guy who sold me the waterpump pulley and a bunch of other stuff, he's got the 6.5" crank pulley...

I know it's an underdriven/overdriven thing...

What's the 4 groove crank pulley for??? I only need 3 rows...

the alternator, of course is 2 groove...

sjd

[road chicken]

I think the 4 groove would have been used with an AIR injection pump car. You should have a three groove setup. One belt for the water and power steering pump. Two for the AC and Alternator. remember to get a matched set of belts for the AC or you'll have one jumping off on occasion.

[steved]

ah....got it...

any explanation to the fact that there's clearly an overdrive/underdrive setup? i.e. a large and small pulley for the crank? or do I just have the wrong crank pulley? mine measures 7.125", and i'm getting one that's 6.5"

sjd

[72RoadRunnerGTX]

The 4 grove crank pulley is correct for A/C and power steering. The water pump pulley is smaller and aligns with the idler pulley and the forward most crank grove. Power steering has its own crank grove, then two remaining for the A/C and alternator twin belts.
Ebay A/C pulley

[steved]

AH..i see...my water pump pulley has a deeper "bell" to it....it's not flat like that one....