Brace yourselves, it's another water pump thread. Does anyone own a legit 1972 350 with Y72 and no A/C? The assembly manual shows 2 configurations of 3 groove pullies being used. One is an A/C build, and one is HD generator and HD cooling with P/S. They both use pullies that are 3-groove, but in the diagram of the no A/C build it is showing that only two belts are used, and that the third groove is left unused. Has anyone seen this to be the case (true)? Because if the engine were built with Y72 only, then my guess is that there was a two groove pulley combination that is not shown.

 

3 groove pulley is correct for non A/C with HD cooling.

Don W

 

Appreciate the response. So, I've drawn you into my next question. The AC three groove water pump pulley must be about 1/2 inch deeper to accommodate the 5.95" water pump then, correct? I ask because my engine started out with standard cooling, short pump using a KN pulley, no fan clutch, no shroud. Trying to duplicate cooling on a Y72 build, I've ended up with a pump that is 5.57" mounted on the engine where the new KM pulley (1/2" deeper) aligns correctly. I have a date coded casting numbers matching water pump I want to use, and it is the 5.95 inch version. So, going back to my original question, if you say that there are real examples of the factory using only two belts on a 3 groove pulley build, I guess that would make sense, and assuming that the depth of the 3 groove pump pulley is also another 1/2 inch taller.
Have I driven you to pop the cap off a cold one yet?

 

I have been over this many times when trying to figure out the correct combo for my 71 W-30. Just go with what you see in the assembly manual and it will be correct. Basically the same water pump / pulley combos for A/C or Y72.
Yes, the 2 groove KM pulley is to be used with the 5.5" pump.
The 72 KO 3 groove pulley is to be used with the 6" pump. Good luck.

Don Wray