# anybody using a 4.5 water pump on 66 or 67?



## Lemans guy (Oct 14, 2014)

so here is a question is anybody using the later 11 bolt 4.5 inch water pump on a 66 or 67 GTO, Lemans or Tempest..........

and 

with a clutch fan?

some do it with electric fan I know, but will it work ok with stock 7 blade clutch fan..that cools great....

it looks when I measure to still give an inch clearance to Radiator,...and the shroud could be trimmed 7/8 of an inch to keep clutch fan half in and half out..

so if anybody has done this how did it work out?


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## 1968gto421 (Mar 28, 2014)

Will interested in what you learn here on this.


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## Lemans guy (Oct 14, 2014)

Sure somebody has done this........


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## 05GTO (Oct 6, 2004)

The 4.5" 11 bolt water pump was used on the early year 69 400s, mid year 69 GM changed to the 4" water pump, my 67 has an early year 69 400 which also has the 4.5" water pump. Are you looking to change from an 8 bolt to the 11 bolt water pump?


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## Lemans guy (Oct 14, 2014)

randy, so you have a 67 GTO with an 11 bolt Timing cover and 4.5 water pump.....

The question is do you have a clutch Fan? and if so how much clearance to radiator?

It will work with an electric fan set up,....I want to know hao it works with a 7 blade stock clutch fan if that is what you have..


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## Lemans guy (Oct 14, 2014)

Randy, a little more time to explain,.....I am considering one of the new serpentine systems, they have them now in Black powder coat and for the setups that have just PS and ALT. they look nice really, and I go for reliability and driveability......

so they require an 11 bolt timing cover and a 4.5 inch tall WP. You are right about the 4 inch WP it was made for a short time in 69 sandwiched between the 3 5/8 inch 8 bolt WP and the 4.5 inch 11 bolt Timing cover and WP.......

Lots of guys have the 11 bolt TC and 4,5 Inch WP on 66 and 67 cars, but many then have electric fans...

I like my 7 blade original clutch fan and shroud cools real good.....

so just trying to see about clearance of 4.5 WP to radiator....with clutch fan

did not have time to explain all that earlier,............


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## 05GTO (Oct 6, 2004)

When I first purchased my 67 in 2006 one of the problems I had was the belt would not stay on and I noticed the pulleys were not lining up, the car's engine had an early 69 400 from a b-body with a 4" water pump. When I replaced the WP to the 4.5" the problem was solved. I'm not using a fan clutch on the engine, only a spacer. If the serpentine system replaces all brackets you may not have problems with belt alignment. If you have more than 1" space between the fan and radiator you should be ok.


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## Lemans guy (Oct 14, 2014)

thanks Randy, so you have answered the question of the 11 bolt and 4.5 WP with a non electric fan.......but no clutch......

do you run a shroud? how does it cool? and haow big is your spacer?

yes the serp sytem will line up nice, also requires a 4 bolt later style Harmonic balancer..


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## 05GTO (Oct 6, 2004)

Here are pictures I took yesterday of my setup;


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## Lemans guy (Oct 14, 2014)

Thnaks that looks great, is that a shroud for a 69? my 66 shroud looks a little different, and the fan as well is that a five blade from what year?


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