# large water pump pully vs smaller pulley



## tspring (Sep 7, 2011)

Which pulley size will provide the most cooling, the large or small diameter pulley.


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## Goat Roper (Oct 28, 2014)

Smaller moves more volume and are harder to find than the 8".
'67 with A/C came with the smaller 6 1/4 inch pulley.


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## GTOJUNIOR (Aug 7, 2011)

Actually for 1967 the factory AC Pulley is 7-1/4" Vs the 8".
Just put one on the '67 myself.








Only one offering this NEW is PP, Correct stamped steel and Pt# 97869069.

1967 Pontiac Engine With A/C 2 Groove Water Pump Pulley 7" Diameter 9786909

This is a nicely made part and fits perfect. All the other suppliers seem to only offering billet aluminum. 

Not sure this will fit/align on the '66, Be careful mixing pulleys can be a PITA.
Always best to utilize complete sets of pulleys Vs. one or more from other applications.


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## Goat Roper (Oct 28, 2014)

My 67 with A/C and A.I.R uses pulley #9788886 same pulley used on 68 A/C cars.
If you look at the spec sheet you posted this is the smaller pulley used on my GTO.
I just measured the extra one I have and it is 6 1/2" O.D and 5 11/16 I.D at the bottom of the outer groove.
In any event the smaller the pulley the more volume but too much volume can run the fluid through the radiator faster than it can remove the heat.


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## tspring (Sep 7, 2011)

I guess I was worried about nothing. According to the service manual Pontiac run at 190 to 200 degrees and came with 190 degree T-stats. The engine runs at 200 with the ac on


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## Goat Roper (Oct 28, 2014)

You are right in there, it should go up to 210 if you run it hard but come back down to 195-200 running normally.


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## GTOJUNIOR (Aug 7, 2011)

Goat Roper said:


> My 67 with A/C and A.I.R uses pulley #9788886 same pulley used on 68 A/C cars.
> If you look at the spec sheet you posted this is the smaller pulley used on my GTO.
> I just measured the extra one I have and it is 6 1/2" O.D and 5 11/16 I.D at the bottom of the outer groove.
> In any event the smaller the pulley the more volume but too much volume can run the fluid through the radiator faster than it can remove the heat.



Sorry about that I read AC, not AC w/A.i.R. 
I'll have to look around and see if that one is being made as well.
Cheers


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## Goat Roper (Oct 28, 2014)

I couldn't find one and Ebay was frustrating since most just listed as GTO pulley with no part #.
Since the net was basically useless I had to go old skool and use the phone.
Percy's Pontiac Parts had one, I had to mail him a check.
I was even told it was the wrong pulley and wasn't used on my GTO.
I had found that same parts list you posted so I knew that was the correct pulley for my goat.
Trying to keep the car original can be a PIA with so many conflicting opinions.
Judges at car shows don't know what they are looking at they don't even know if the engine is a Pontiac or a Chevy.
The last one in Wrightwood had quite a few really nice restored muscle cars so I figured my chances of winning in the muscle car category was nil.
The car selected?
A 1972 Nova.
LOL!


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## Pinion head (Jan 3, 2015)

Something Important that has not been touched on. When a smaller diam AC application wp pulley was installed, a larger diameter crank pulley was also used. Just using the stock smaller diameter crank pulley with a small diam wp pulley like the "886" will turn the waterpump too quickly. The coolant has to have time to do its job. 

On clean factory pulleys, & how hard they are to come up, hauling in partscars & pulling parts in the Southern Plains, Texas, NM, I used to be like a big kid in a monster toy box surrounded by vintage AC application pulleys. '67 & all the later non AC pulleys have always been something I pulled further up north. Have a very deep supply of original pulleys, some applications I do run out of from time to time, but then reload on them.. Such is again the case for the '70 model AC appl pulleys that I often ship out.


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## GTOJUNIOR (Aug 7, 2011)

Any idea on size of HB/Pulley nothing in as far as size listed;









I just swapped out the 8" 9786819, with the 7+" 9786909 2V fan pulley.


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## Pinion head (Jan 3, 2015)

Will see what I have left for 6 bolt pulley/damper stacks. Seldom get a request for those. Do know the '67 crank pulleys use wider belt grooves than '65 & 66's.


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