C2 65 BB water pump vs. 66 BB pump

[Steven S.]

I noticed when browsing through pump rebuild kits from a Corvette supplier that there was a different kit for 65 pumps that is supposed to have a pump bearing/shaft that is 3/16 shorter than the 66-67 pump kits. What was the difference here? Was there a different part number for the pump in 65, or was there a change in hub installed heights? Am I correct that 65 and 66 BB's shared the same water pump and crank pulleys?
Thank you,
Steve

[Joe L.]

Re: C2 65 BB water pump vs. 66 BB pump

Steve------

There should be no difference, at all, between 1965 and 1966 big block waterpumps. Both pumps used casting GM #3856284 and both were of assembly part number GM #3876173. The rear backing plate of the pumps changed which MIGHT affect the shaft length, but I as I recall, this change occurred after 1966. So, I don't see why there would have been any difference between 1965 and 1966 pumps.

Waterpump pullies were the same for 1965 L-78, 1966 L-36, and 1966 L-72. Crank pullies were the same for all three applications, as well.

From what I can tell, the hub spacing dimension for the waterpump flange was 5-3/4" for all 1965-69 Corvette big block waterpumps.

[Steven S.]

Re: C2 65 BB water pump vs. 66 BB pump

Thanks again Joe, you are a wealth of information!

Steve