Water pump replacement

[DartVadar]

So I'm in the process of replacing the water pump in my 73 dart 318, it's an ac car, is there a difference between the pump on an ac and a non ac car?

 

[1970Duster]

Number of blades on it.

 

[BillGrissom]

As I recall, AC water pumps have fewer blades. Sound backwards? Many here tried to reason it out, but we kept returning to the fact(?) that the designers would want to maximize water flow in all cars. The answer most here settled on was that AC cars had different pulley diameter ratios, so the water pump speeds varied, which is the reason the #blades differed. Of course, we are just speculating and the designers are mostly in nursing homes or buried now.

 

[gregpurcell]

I've always been a big block guy so I can only answer in those terms. On the 383-440, the non-ac pump had larger impellers but fewer of them. The ac pump had a much larger circle of blades but they were much shorter (I'll look and see if I can get pics). The idea was that the AC pump was supposed to move more water while using less horsepower. All of the racing manuals said to run the ac water pump on your engine.