How fast shood the water pump spin?

[Kenall]

i must replace the double groove crankshaft pully with a triple unit so i can install my aftermarket AC on my small block chevy in the wag. this wood be used in conjunction with a double groove water pump pully. the water pump wood now have the AC belt and the alt belt riding on it, no big deal but.

all the triple OE grooved pullys i find have 2 different diameters on the same pully. the larger to run the water pump and the alt, the smaller to run to PS/AC.

if i use my double groove water pump pully with the AC and the alt belt, the corresponding crankshaft pully groove driving the alt wood be the larger of the 2 diameters. this means the AC belt will be driven from a smaller crank pully than the alt but both belts wood be touching the water pump pully at the same time..this is bad..right??

mr.gasket sells a triple unit for my situation that looks like it wood work, but the pullys are all the same diameter. this wood turn the alt/water pump at a slower rpm then GM designed.

what happens when u slo down the water pump, better cooling worse cooling?

[River Beast]

hmm... I just talked to Ramjet on this for his setup...I think the smaller pulleys would be considered under-drives and spinning less would not be beneficial to cooling...I THINK....

considering that we do alot of low rpm stuff, the larger pulley would provide more cooling effort at a lower rpm...

am I on the right track here?

[Kenall]

thats the direction i have been leaning...GM used a different dia pully for a reason.

ill have to weld on an idler pully atop the alt bracket to pass the AC belt around the P side of the water pump (WP). a job the dual groove WP pully was gonna do b4 i found my error.

[River Beast]

Watch the offsets though... I have seen too many people swap out the pulleys for some reason or another, and the grooves don't line up...watch for it Ken...good luck

[RamJetFSJ]

Todd, You are correct. An "Underdrive Pulley" is a smaller crank pulley, and it puts less drag on the motor resulting is a little more power, but it turns everything else (AC, Water pump, Alt, PS), at lower RPMS. Meaning at Idle especially, all the accessories will be spinning slower, pumping less water through the system, putting out less AMPS, less pressure in the power steering/AC etc.

Ive got a big honking Crank pulley. A cheapy chrome steel one, but its huge. The biggest crank pulley possible (just about touches the water pump pulley). Puts a little drag on the motor compared to a underdrive pulley, but pumps more water, puts out more AMPs etc throughout the RPM range.

It has 3 equal diam groove. the one closest to the block runs just to the PS, the middle one runs to the water pump and ALt. And the last one will go to the water pump and the AC.

Kenall, I can try and figure out where I got it if you want.

[Kenall]

ben sounds great.

for me the inner most grove will run the PS and the next will run the AC. the outer will run the alt/WP.

the inner and middle grooves are the same dia while the outer is the largest to run the ALT and the WP.

however, the center grove that the AC belt will be driven from is also lined up with the outer groove on the PS pully. so the AC belt will come up the P side of the WP to the inner groove on the dual groove LWP WP pully to the AC comp, down to the outer groove on the PS and then back to the crank. this gives me 2 belts on the WP and the PS.

if i cant find the proper size crank pully, ill do as i side with the idler pully on the ALT bracket.

but here lies another snake...if i increase the AC/PS pullys to the same dia as the ALT/WP pullys do i run the risk of overspin at crank rpm of 2900?

what happens when the AC and the PS spin too fast?

[Snakeyes_Tx]

Hey! What's this talk about Snake's huh? :D

Anyhow... how about just a smaller water pump pulley?

I guess the next question would be is where to find one. I think since our pulleys are similar to a small block chevy's, we could just slide say a 350's pulley over the water pump instead of ours.. or atleast a smaller one so it'd turn faster.