BudW water pump pulleys

Remow2112

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There were 2 water pumps for the F body SB. A 6 vane and an 8 vane. The 6 is for AC cars. I have seen a couple places that F body SB AC cars also had a smaller water pump pulley. Does anyone know or BudW can you check your parts books and see if there is different part numbers for water pump pulley AC vs non AC?

Thanks!
 
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BudW

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Let me check.
I know there is a 6 and 8-blade fan for the Big blocks as well as a water pump pulley diameter difference on big blocks - but not aware of that for small blocks. Let me check into that and get back.

I do know the '70's police or HD water pumps have a larger diameter bearing and that pulley makes the housing different. They finally changed the 80's water pumps to the police style, but don't remember when.
BudW
 

volare 1977

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pic from 77 parts book

abc.jpg
 

volare 1977

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108 is the 8 vane w/o air for 318, 360 shows the same 109 pump for both a/c and non a/c . I assume the 6 vane is for the 109. I found someone online said

determined by the size of the crank pulley.
The small pulley used the 8 vane and the larger pulley used
the 6 vane..same flow.
I don`t know if that is for sure a fact on the pulley sizes. What you all think?
 
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XfbodyX

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Pull out your cop car insert and military truck/ambulance insert and that will solve your puzzle. They list the special "separate" parts used.

At times its easier just to lay the pulleys out on the bench or floor of known setups.
 

XfbodyX

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I will scan them this weekend if needed, the OP remow never stated why he asked.

Are you trying to match a set or in the end just turn your pump faster?
 

BudW

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It seams to be a more complicated answer - but pulley size and if car has A/C is the big determination.
The water pump, p/n 3780109, was used for most small blocks. I found nothing about vane numbers but 6 vane and 8 vane sounds about right (for '109 and '108 pumps accordingly).

It appears the 318 (only) on striped down versions (like my wagon) might be the only ones that used the '108 pump and pulley system. I will have more data soon, but up against a huge work deadline.

At times its easier just to lay the pulleys out on the bench or floor of known setups.
I totally agree with that.

Also, Chrysler pulleys have part numbers stamped on them (which might be under layers of paint and/or grease).
This is from my '77 wagon (no A/C):
20180622_154723r.jpg

The number stamped is 2951836 with last 2 digits stamped larger (to aid assembly line workers).
abc.jpg

Having a complete pulley set is a huge help when you have multiple engines/pulleys/brackets in your garage, like X has, as well as myself. At least the pulleys are stamped with the part number.

Personally, I have three "unmarked" fan/crank pulleys in my "To Do" pile to chase down the (stamped on) part numbers so I can determine what they are for - which is something I just haven't gotten around to yet. Now mumbling incoherently about marking parts upon removal so one will know what they are for later on . . .

Pull out your cop car insert and military truck/ambulance insert and that will solve your puzzle. They list the special "separate" parts used.
I do not have this information either - so it would be nice to see/have.

Are you trying to match a set or in the end just turn your pump faster?
A good and valid question.

BudW
 

Remow2112

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You guys rock! I recently got a 76 RR that I am restoring. It has a 360 in it out of a truck. No idea if the truck motor was AC or not. But the RR was an AC car. Since I intend to swap the cam I really want to make sure the pulley and water pump are correct.

When I was racing a 360 I had changed to a truck water pump because they had a 1/2" shaft vs the smaller shaft for cars. I always fought overheating. Years later on another forum someone brought up the fact that AC cars used 6 vane and non AC used 8. Went and looked and sure enough the truck pump I had been using was an 8. So doing research in a couple of places people brought up the concept that FMJ cars had different pulleys AC vs non AC.

I have several F bodies around but they are all AC cars.

I figured BudW has all the parts books, it seemed, and if there is a pulley difference it should be obvious in the parts. LOL, apparently not so much. I have 2 untouched AC cars and I will see if I can get a number off the water pump pulley.
 

XfbodyX

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Here is an org. non ac f. If you wanted to use the real smaller pulley youd have to use the short snout pump/fan spacer or use the different crank pulley.

thumbnail_IMG_20210806_191141923.jpg
 

Remow2112

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That seems pretty definitive XfbodyX. They are different sizes and maybe so are the crank pulleys. Can you measure the width of the 2 water pump pulleys? That would be a real easy way to check which pulley is in place.

BudW, understand deadlines! Look forward to the info when you get time.
 

XfbodyX

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. No one says you cant run a better pump like the last one is an older be cool 12 and there newer one have a 12 vane billet impeller.

Why limit yourself to oem?

DSC03786.JPG


DSC03787.JPG


DSC03792.JPG


DSC03793.JPG


DSC03794.JPG
 

Remow2112

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I have a 77 RR in the backyard that is original. (as far as I can tell) and it appears to be the smaller pulley. This is the number on the water pump pulley. 37511 26. Which I don't see in BudW's listings.

77 Volare Small Water Pump pulley.jpg
 

Remow2112

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I didn't intend to limit myself to a OEM water pump, but I did want to make sure I have the correct pullet setup. Since I am restoring I plan on having the AC working. VERY important in SW Arizona. :D

The info also might help someone else on the board that is fighting overheating and have no idea why.

I am kind of stunned that Ma Mopar bothered with 2 different pulleys and water pumps. Seems to me it would have been cheaper just to the put the AC pulley and water pump on all of them.
 

XfbodyX

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Ok, IM sorry I was going off your references to your track or race car mentioned for some reason.
 

Remow2112

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Gotcha, it was my race car when I had a 360 that was overheating and was frustrating me. In this case I just want to build a driver similar to my original RR.
 

BudW

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I do have a lot of books but a long way from everything Mopar known to man (or FMJ's, for that matter).

I don't know why the non-A/C 318's (or for that matter, the older big blocks with no-A/C) have a different pulley size and blade count pumps - but I suspect it might have something to do with making the plain Jane (no option) cars as cheap as they can make it, by saving a penny here and there . . . maybe. Even the plain Jane 318's with air pump got the A/C water pump (and diameter pulleys) - so i can only speculate.

The water pump (fan) pulley on my '77 318 no A/C (p/n 2951836) is between 6.827" to 6.877" in diameter.
Your water pump pulley is (p/n 3769130) is between 6.377" to 6.462" - so roughly 1/2" smaller diameter.
The smaller diameter pulley would rotate the pump about 6.4% faster - which might make up for the difference on fewer impeller blades (IDK - just taking tossing it out there to see what sticks to the wall).

The later small blocks (and earlier big blocks) finally went to one water pump for all - which should have been the choice from the beginning.

The later small blocks went to the police style water pump across the board, with larger shaft/bearings and are the ones with the different water pump housing, and I "think" they all have the same pump blade count.
The small blocks with the bigger shaft/bigger bearings have this shape:
SB Water Pump, Large.jpg

and older pumps with smaller shaft/bearings look like this:
SB Water Pump, Small.jpg


On a side note, water pumps work more off of centrifugal force than actually pumping. They do pump, but it seams like they create more vacuum than pressure, sometimes. Our engines have to have a coil spring inserted into the lower radiator hose - to keep the hose from collapsing. Even then, if you gun an engine, you can see the lower radiator hose shrink for a moment until the rest of water catches up.
NOTE: don't gun the engine with your head in the pathway of the fan blade! I don't want to see anyone lose their head over a freak accident.
BudW
 
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