Pulley Geometry

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Aug 30, 2009 | 05:21 PM

Dantana

Thread Starter

Burning Brakes

Joined: Apr 2007

Posts: 1,028

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From: SOUTH ELGIN IL

Pulley Geometry

While I am installing my new DeWitts I purchased a new Edelbrock short water pump with a 5/8" pilot. Of course my water pump pulley is 3/4" so I need to buy a new one - which I was going to do anyway. Since I'm doing that I figure I'll get a new polished crank pulley too. Problem is that I have a double groove crank pulley with another slightly smaller diameter single mounted to it, effectively making it a 3 groove. My power steering pump lines up with the outside most groove on my "3 Groove" crank pulley. All the short water pump crank pulleys I have seen at Summit, etc are 2 groove, 3 grooves are only available in the long neck water pump section.

Should I get the 3 groove?

I should mention I am currently running a ZZ4.

EDIT: I see now that the second pulley is the "power steering add on pulley" on corvettecentral.com. Doesn't seem to come polished so I still need a strategy...

Thanks,
Dan

Last edited by Dantana; Aug 30, 2009 at 05:36 PM.

Aug 30, 2009 | 07:18 PM

0grandmastercorvette

Former Vendor

Joined: Apr 2009

Posts: 766

Likes: 3

From: Charlotte North Carolina 704-394-5150

My best advice is to be careful in changing the diameters and offsets of the water pump pulley to much because it can cause the water flow charastics to change and possibly cause the water to circulate faster than you may want and cause for heat issues due to the water is not able to stay in the radiator long enough to cool down....due to this inceased flow....along with trying to make the power steering pulley line up. BEEN THERE...DONE THAT...

I always hate when I have to fix a car that has different pulleys on them because....it is want it is... and when you drastically change flow, it is often times extremely hard to correct without putting the correct pulleys back on the engine. I have had a sleeve machined to take up the difference..but that was also using the clutch fan assembly.... and factory water pump pulley.

Just check your water flow at idle and make sure it is not flowing to fast. Best of luck and that is the only advice I can give...unless you find a company that can deal with your issues. Trying to find parts from different manufacturers is always a pain for me also...sometimes they work...sometimes they do not.. but nonetheless...it is time consuming.
"DUB"

Aug 30, 2009 | 07:19 PM

C3 Stroker

Safety Car

Joined: Oct 2004

Posts: 3,926

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From: Youngstown Ohio

Pulley Setup

Here are some pics of my pulley setup....they are aftermarket, and the crank pulley is 3 groove; it is also smaller diameter than stock for 25% underdrive of all accessories. The outermost groove will align correctly with the P/S pump. I bought it years ago, from P.A.W. Parts.....I believe it's still available, about 5 1/4" diam., aluminum.

Aug 31, 2009 | 09:33 AM

71rdster

Drifting

Joined: Jul 2005

Posts: 1,562

Likes: 2

From: Spring Texas

You have the wrong waterpump. The Corvette waterpump is a "short" waterpump, but there is more than the shaft size to differentiate it from a standard chevy short pump. The correct Corvette Pump is slightly longer (1/4" I think) than the standard short Chevy pump.

Get the correct waterpump and use your oeiginal pulleys. If you want to upgrade to shiny bling pulleys, March Performance has Corvette specific billet alumininum pulleys, or you can buy chromed pulleys from many of the forum sponsor/vendors.

Aug 31, 2009 | 10:22 AM

Dantana

Thread Starter

Burning Brakes

Joined: Apr 2007

Posts: 1,028

Likes: 1

From: SOUTH ELGIN IL

can anyone please comment on if I really need corvette specific pulleys and water pump anymore? I told Edelbrock what I had and they sent me this short neck pump. Assuming it is incorrect I have no AC and am running GM ZZ4 crate (not corvette specific). Any reason why I can't just go with any other normal set up for the front of a small block chevy?

I'm very interested in responses. Thanks.

Aug 31, 2009 | 12:12 PM

pws69

Melting Slicks

Joined: Nov 2001

Posts: 2,668

Likes: 43

From: Eastern US XX

Information for the correct pump for your car/engine (stock):

Short Style Pump for 1971-76 Corvettes (.750" pilot shaft)
Fits all 1971-76 small block Corvettes.
Has heavy duty .750" ball/roller bearing.
Dimension from block surface to hub 5.812". Inlet diameter 1.80"

So if you are using the original pulleys, then this is what you need. If you are NOT using original pulleys, then use whatever you want as long as the grooves all line up correctly.

Last edited by pws69; Aug 31, 2009 at 12:14 PM.

Aug 31, 2009 | 01:48 PM

Dantana

Thread Starter

Burning Brakes

Joined: Apr 2007

Posts: 1,028

Likes: 1

From: SOUTH ELGIN IL

Quote:

Originally Posted by pws69

Aug 31, 2009 | 06:21 PM

C3 Stroker

Safety Car

Joined: Oct 2004

Posts: 3,926

Likes: 739

From: Youngstown Ohio

Quote:

Originally Posted by Dantana

The stock power steering bracket on C3's is made to line up the pulleys with the short water pump; ditto for the alternator brackets. The crank pulleys may not line up exactly, but you can correct for that. Also, the long water pump pushes everything (pulleywise) around 3/4" closer to the radiator.....so if you aligned your pulleys OK, you can still have issues of your fan hitting the shroud or radiator. (Electric fans would probably fit OK.)