Pulleys and water pump
I mocked up the water pump, A/C and Power steering last night. Using the book “How to Restore Your Pontiac GTO” I found I have the following part numbers.
Item - Part Number - Years - Comments
Crankshaft Pulley - 9790843 YC - 1968–1970 - Single Groove
Crankshaft Pulley - 9790842 YB - 1968-1970 - Two Groove
Water Pump / Fan Pulley - 9782679 XJ - 1966 - Two Groove
Power Steering Pulley - 9782671 XH - 1966 - Single Groove
Power Steering Bracket - 9778848 - 1966 - Aluminum
A/C Mounting Bracket - 9782661 - 1968-1970 - Aluminum
The book did not specify what the part number should be for the A/C bracket on a 1966. I looked around some data plate decoding sites, and the A/C may not have been on the car originally.
With the long snout 4.5” water pump and the other components bolted on, there appears to be about 7/8” offset between the water pump pulley and the crank’s double pulley. The Crank’s rear single groove pulley is aligned well with the A/C pulley. The Power steering pulley is in alignment with front groove of the Crank’s double pulley.
So it appears that I will need the short water pump to make up some of the 7/8” offset unless the correct pulley for the ’69 waterpump has an exceptionally deep backspacing.
I am assuming that there may be two sets of ’69 water pump pulley since I have seen some listings for early ’69 water pumps (short) and the more common longer ’69 water pump. And Ames shows pulley sets for early and late ’69.
My book shows two different 69 water pump pulley’s, but they may be just different diameters.
9796062 - exc F/8 HT M40 less VP fan - 7 3/16” dia
979606 - F/8 HT M40 less VP fan - 6 ½” dia
I am not sure what the F/8 HT M40 signifies. I think the VP stands for variable pitch fan.
The book does not address the long and short style water pumps. Maybe the short style was only used on the 350 engines.
Does anyone know which if either pulley will work, or if one has more backspacing than the other?
Do the late ’69 water pump pulleys have an exceptional amount of backspacing?
My confusion is that the crank pulleys line up with the power steering and A/C pulleys, so it appears to be a water pump pulley problem.
Or am I looking at finding a custom sized water pump pulley?
Thank you,
Doug
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