Spinning the water pump faster?

I was having an issue with pulling hot air back through the radiator. I am running a fiberglass hood and there was no seal from the hood to the rad support. When I added a piece of foam rubber to the undersid of my hood there was a significant improvement but it's still running too hot when in traffic. The engine was rebuilt back in 1988 and I have been maintaining the cooling system since. It's been flushed out on more than one occasion. This is why I'm thinking about changing the diameter of my water pump pulley to a smaller aftermarket type or if the A/C factory pulley was smaller then I would give that a try. Also I might try a clutch fan but I have to find one that will clear the belt for the supercharger.

Thanks for the input guys!

1968FormulaS340 said

Normally if it cools fine at speed but gets hot at a stop it is airflow. Take some pics of the radiator mounting and over all cooling system including the under side of the hood.


You don't even need a fan over about 35-40ish mph.

My bet is that you are pulling hot engine air back around and through your radiator.

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