Water Pump Pulley

[Clark D.]

Finally getting the engine back together for my 1966 coupe. I have found the water pump pully is sticking out about quarter of an inch past the crankshaft pully causing the belt not to ride correctly. Here is what I have:

1. 1966 327 Engine NOM
2. 8 inch damper
3. Crankshaft pully #3755820
4. Waterpump pully #3788472
5. Aftermarket waterpump (short)

Does anyone have any thoughts to why this is happening?

Thanks Clark #42490

[Jack H.]

Re: Water Pump Pulley

The water pump hub is press fit onto the pump's shaft and it might not be installed to correct/original factory spec if all else is correct (I presume you've checked the pulley part numbers against your copy of the AIM to verify they ARE correct/originals). But, 1/4-inch is a LOT of mismatch for the typical water pump rebuilder....

[Joe L.]

Re: Water Pump Pulley

Clark-----

The pullies you have are the correct ones IF the engine is a 300 hp without C-60 and without K-19. However, such an engine should not have an 8" damper; it should be about 6-1/2". Nevertheless, the pulley system should work with an 8" damper.

One thing that could be a problem is that all of the 1955-70 small block short waterpumps did not have the same hub-spacing. Many folks don't know that, but that's the way it was. 1962-E66 small blocks used a waterpump that had the hub spaced out 1/8" greater than earlier or later small blocks. That's because these years did not use a pulley reinforcement. If the pulley you have has the reinforcement and the waterpump has a hub spacing designed for a pulley without it, then you'll end up with the situation that you described. It should be about an 1/8" mis-alignment, though, and not 1/4".

If you need to adjust the waterpump flange, then you have to remove the pump from the engine. Then, you have to remove the backing plate and support the rear of the pump shaft before pressing the hub back the additional amount required. You cannot simply press (or otherwise drive) the flange back without supporting the rear of the shaft without risking serious damage to the bearing/shaft assembly.