[73gtolive]

I've always been taught that low speed over heating is airflow through the radiator and over heating at speed is water flow. I've battled this with 2 Mopars and it is no fun. Watching that needle creep up while sitting at a red light takes all the fun out of driving it.

Do you have a shroud ? My belief is that in moderate situations that the factory designed cooling system is best. Even better if the factory offered a heavy duty cooling system. Find those parts. That means all the correct shrouds, fans clutches, fan, distances from Radiator etc. That also means a brass radiator that is in good condition. I know lots of people have good luck mixing and matching parts and that is the back bone of hot rodding but I have had mixed results when trying to keep some of these beast cool. The factory engineers designed these cars to run cool in all conditions. As much as we all cuss them, they were probably smarter than most of us are when they figured these cooling systems out.

I have used an aluminum radiator in a small block dart but ended up spending a good amount of cash for their custom made shroud (Wizard Cooling) and then put the right diameter fan on it. I can sit at idle in the staging lanes on a 95 degree day and leave the car running with out it overheating.

Not sure this applies to a Pontiac but I would think it would. A poor tune can cause your car to run hot. A lean condition will not be in your favor.

Good Luck !