this was a great thread to read. My friends 440 daytona ran hot when he put a new pump on (think it was a 440source believe it or not), and when he went and talked to another daytona owner, who convinced him the stock pump is a better bet to get rebuilt (which he did), it ran cooler right away.

It always pays to check the fan clutch on high milege cars, I had a 395/425hp vette that is factory 11:1 compression. The new edlebrock water pump I put on that was not as good as the original one (rebuilt), it actually ran hotter. It did not move the water at idle like the factory pump, at all. Also, the fan clutch, was shot with the fluid that leaked out over time. I always vindicate looking at the fan clutch, like said on this thread.

Also, if your car is a high compression motor, I strongly recommend keeping the octane high. My vette runs great, if its largely on racing fuel. Nice and cool. If I ever put in 93 octane, if I have to cause it gets low, it wants to run hot, then overheats. With that car, the octane level makes all the difference. I also run it rich, to help keep it cool. A lean carb will come back and bite you with 10s of degrees on the temp guage. My friends daytona shed some temp when he added some octane booster.

my 2 cents. always rebuilt the factory pump first (do not assume new pumps are better than the factory pump), make sure the fan clutch locks up at temperature (and does not slip), and have the right fuel/octane and set the carb on the rich side.