Overdrive Pulley Set?

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mopowers

mopowers

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Does one make or sell a single v-groove pulley set for a small block that overdrives the water pump? I've seen a serpentine setup from CVF that overdrives the water pump, but can't seem to find one that's a single v-groove.
 
in most cases it makes no sense because you have cavitation when you run the wp at to high speed. Are youre engine running a lot at idle?
 
Just so I’m on the same page….

To overdrive the pump, you need a smaller pulley.
This is what your looking for?

If so, I got my smaller pulley from March.
 
rumblefish360 said:
Just so I’m on the same page….

To overdrive the pump, you need a smaller pulley.
This is what your looking for?

If so, I got my smaller pulley from March.
Click to expand...

Yes - I'm looking for a single v-groove pulley set where the water pump pulley has a smaller diameter than the crank pulley. It seems like the only factor overdrive sets were for A/C cars that used huge multi-groove crank pulleys, which I don't need.

I'll look to see if March has a water pump pulley that'll work with a single groove crank pulley. The problem I've encountered is that the single groove crank pulleys I've found are a pretty small diameter.
 
mopowers said:
Yes, it's a street car that see lots of idle time. Speeding the pump and fan up slightly would be helpful in my case.
Click to expand...

It won't hurt the low speed charging any, either.
 
Do u have a depth measurement of each pulley. What are the sizes u have now? Cast iron or alum w/p? May be able to change just the bottom one also. How much clearance between them? Kim
 
oldkimmer said:
Do u have a depth measurement of each pulley. What are the sizes u have now? Cast iron or alum w/p? May be able to change just the bottom one also. How much clearance between them? Kim
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Its the later aluminum w/p.

I've tried finding just a larger crank pulley or a smaller water pump pulley, and no dice.

I'll take a couple photos and do some measuring and let you know.
 
oldkimmer said:
Do u have a depth measurement of each pulley. What are the sizes u have now? Cast iron or alum w/p? May be able to change just the bottom one also. How much clearance between them? Kim
Click to expand...

My current water pump pulley measured the best I could with it installed is: 6.75" OD and 3" from the fan mounting surface to the outside edge.

Current crank pulley is a 2-groove for P/S. It measured 6.5" OD and 2.25" from the mounting surface to the outside of inner groove that is used.

I believe these are the standard pulley set for early 70's SB non-A/C model w/ P/S, though I could be wrong. These measurements give a 0.96:1 ratio. I'd love to find a pulley or set that provide a 1.2-1.3:1 ratio.

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oldkimmer said:
Ok. I’ll do some checking. A 6 inch or so would be ideal. Kim
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Thanks Kim. A 6" w/p pulley would put me at 1.08:1. If you have a 5.5"-6" w/p with a larger crank pulley, that'd work too.

One other issue I have is spacing. I don't have any extra room to space the w/p pulley forward at all for belt alignment, unfortunately.
 
Why not just raise the idle speed a couple hundred RPM? You'll spin the pump and fan faster and also sling more oil up onto the cam. If you are heating up at idle you probably have an airflow issue more than coolant flow.
 
C130 Chief said:
Why not just raise the idle speed a couple hundred RPM? You'll spin the pump and fan faster and also sling more oil up onto the cam. If you are heating up at idle you probably have an airflow issue more than coolant flow.
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Personal preference, I guess. I'd rather overdrive the pump and fan slightly than raise the idle to 1000 rpm. The car doesn't have an overheating issue. The temp just creeps a little more than I'm comfortable with at stop lights. Raising RPMs with my foot brings it right back down. Pretty sure the right pulleys would work great. Another option is finding a fan with more pitch.
 
A 68 A/C water pump pulley is smaller than what your running. This is an 8 arm impeller? With an anti cavitation plate?
 
I think march might make an overdrive crank pulley. I saw it when I bought the under drive one.
 
furrystump said:
A 68 A/C water pump pulley is smaller than what your running. This is an 8 arm impeller? With an anti cavitation plate?
Click to expand...

Thanks! I'll have to look into this. And for a water pump, I'm running a milodon high flow unit (8-blade w/ anti-cavitation plate).

furrystump said:
I think march might make an overdrive crank pulley. I saw it when I bought the under drive one.
Click to expand...

Thanks for the lead. I just called them and they do sell a 1:1 set as their "high flow" set, which consists of a 6.5" crank pulley and a 6.5" w/p pulley. Unfortunately, this isn't much different than what I've currently got.
 
I know my original 68 A/C water pump is a small pulley. It was spinning so fast at 6400 rpm it was causing cavitation pits on the timing cover pretty quickly. Went under drive on the crank and installed anti cavitation plate and it stop throwing belts off.
 
We’re you able to find anything? I want to overdrive my water pump as well. I had to use an underdrive pulley for my crank and trigger wheel setup. Need to spin the fan faster
 
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