chevy short water pump question...

I picked up a G.M. aluminum short water pump for a SBC at the charlotte swap meet. Well... I put it on the motor we are going to use in our next project and the upper pulley is misaligned by about 1/4 inch (too far out) from the bottom pulley. The fan snout also had a 3/4 pilot instead of the normal 5/8. The fan hub did have both bolt patterns in it though. The balancer is pressed on all the way ,and the bottom pulley measures the same distance out from the block as another motor we have running. Did G.M. make a slightly longer "short" water pump, maybe for a later model corvette??Also, I think this pump was rebuilt. Anyone run into this before? thanks

 

A-Bomb, I used the same pump on my blown small block. I had to sim out the lower pulley to match the upper and drill out the top pulley snout hole to 3/4. Wayne

 

that's the water pump from a 85-early 90s Corvette with the reverse rotation serpentine belt setup.

You can make it work, either do what he said or pull the rear cover off so you can support the shaft and press the pully hub on further.

There are indeed some different lengths of short small block pumps, I've had to press or pull hubs a skosch to get them to align...

 

Reverse rotation? Will it still pump OK?
~ Paul
aka "Tha Driver"

A flower is nothing more than an educated weed.

 

wayne miller says it works ok....the impellers are pretty crude, so I'm not surprised that it works. I have a couple of these pumps that I never bothered to put on a car.

 

There are also different balancers, some are thicker, some thinner, and bottom pulleys are offset accordingly... sometimes you just have to find the combination that works for you I guess.... If your motor is 69 or later, Its probly got the fatter balancer, which pushes everything out farther cuz motors after that year came with "LONG" water pumps.... I Think.... Chevy guys Does this sound accurate?

 

The 350 uses a bigger balancer, there were two different diameters. The long pump was first used in 69, but trucks and Vettes kept the short pump.

 

Thanks for your thoughts guys. First I am going to pull off the back cover and see if it is a reverse rotation. If it is I probably will just use another short pump that has the correct rotation. The motor is a 1973 350 with the 8 inch balancer. I will be sure to check the next pump closely . I know I can get one to work without shimming the bottom pulley out. I have the same set-up on our "A" coupe and it lines up perfectly. It has a flowkooler short aluminum pump on it. By the way it cools great,even with a 15 inch mechanical fan and no shroud. It has a U.S. Radiator (heavy-duty) but this is not the "desert cooler" model. I will let you know which pump/balancer/pulley combo works out right.