Water Pump Pulleys- V-Belt

1. Year and pump depth come first

Pontiac used a 4 inch water pump through 1968 and into early 1969 1/2, then moved to the taller 4.5 inch pump on the 11-bolt timing cover. The pulley has to be cut for the pump you actually have, not the year on the title.

2. The conversion pulley most people are actually looking for

If you are putting a 4.5 inch water pump onto an engine that left the factory with the early 4 inch pump and 8-bolt cover, the 6.5 inch two-groove Butler pulley is the piece that makes it work. It is the same pulley Butler supplies in its 8-bolt to 11-bolt timing cover conversion kit, and it lets the later pump drive at the correct offset. Butler lists it as an A/C pulley because of the smaller diameter, but that smaller diameter also spins the pump faster, so it is a reasonable choice on a non-A/C car that runs warm.

3. One groove or two

Count the accessories, not the belts you have now. A single groove pulley drives the crank to pump path and nothing else, which is correct on a stripped car with only an alternator on the other side. Two grooves are what you need once power steering or air conditioning joins the front of the engine, and the second groove has to line up with the matching groove on the crank pulley. Mixing a two-groove water pump pulley with a single groove crank pulley is the most common way to end up with a belt that will not stay on.

4. Alignment, finish and the shim kit

Billet pulleys run truer than a stamped steel original, which matters most at high rpm, and the finishes here are polished or billet aluminum, black anodized and black powder coat. Butler also stocks the Moroso pulley shim kit, two 1/16 inch spacers and one 1/8 inch spacer that install between the pulley and the drive flange to correct belt alignment. Set a straightedge across the crank and pump pulleys before you call the job done; a belt that runs at an angle will squeal and shed cords long before it breaks.