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Discussion Starter #1
I know this is a topic that has been discussed many times but since I still have the problem I thought I would ask again. i have a 67 GTO, 400, no ram air, quadra jet carb, 73 heads with cross over blocked off. As long as I'm moving it runs at 190 degrees. As soon as I stop for traffic it runs up to 230 degrees. What I did so far. New "desert cooler rad from Ames, new high volume water pump, new clutch fan, new shroud, new 160 thermostat, seven blade fan, new 15 lb rad cap. What's left? I've read about the space between water pump inpeller and diverter plate not being correct. What should that space be? How could it have changed? How do I ajust the space? Some other info, timing seems good. Checked it with a timing light. Starts fast, runs good . No ping, no milky oil like a blown gasket. I'm stumped. Any help would be greatly appreciated.
 

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Ditto:

same problem if I idled for a minute or drove a steady 3000 rpm's or better....moved my fan using a 4 inch spacer problem solved
 

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i installed a smaller water pump pulley i got from ram air restoration, also i dont quite understand this bit but my mechanic installed a edlebrock inlet manifold he blocked off the channels well actually he cut them off and welded it up, these are the channels that went up towards carby.. ..now less heat going up under the carby... also the manifold is much lighter than the stock, its painted same factory colours and looks the same most would not know its changed....of course more power too...mine sits on 190 max ....was around 215 odd before these mods
 

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Discussion Starter #4
If I installed a fan spacer the fan would be inside the shroud. From what I read the fan blades should be half in and half out of the shroud. Yes , no?
 

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Yes. And set the water pump plate clearance. Many articles here telling how if you do a search. Critical. The reason the clearance changes is because remplacement water pumps don't always have the impellor pressed on the shaft at the exact specified location. The result is an inefficient pump. You r poblem clearly shows that you are not pulling enough air thru the radiator core at idle speeds. I would Do the clearance check, and then go from there: fan spacing, fan pitch, etc. Is it an OEM fan or aftermarket? The original stuff works the best.
 

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How do I adjust the space?
It almost couldn't be any easier...

* Pull the pump and the plate
* Remove the gasket between the pump and the plate
* Support the pump by the housing (-not- by the shaft!)
* Lay the plate on the pump with no gasket between them
* "Work it" with a body hammer, other hammer, etc. all around the opening until the plate just barely touches the impeller all the way around.
* Reinstall with a new gaskets in the right places.

Betcha you'll see a huge improvement.

Bear
 

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Discussion Starter #8 (Edited)
THANKS Bear and geeteeoguy, now I have a direction to go. Makes sense to me. I don't know if its an OEM fan or not. It was on the car when I got it. It's a seven blade fan. Again thanks guys, much appreciated.
 

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:agree Harley, When you work the plate gently, and lovingly .. I USE A DEAD BLOW HAMMER AND A WOOD BLOCK...leave a small space...the Gasket will space the pump from the plate a bit more..this gives a nice close fit...makes a big difference if the gap was too big originally!!!! Eric :cheers
 
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