My 455 will run 160-180 all day as long as im at highway speeds but before i had it tuned correctly it would overheat in traffic. Since then i put a new ignition system in it set the timeing and adjusted the carb so it was not flooding. But i have not taken it into traffic becasue of fear of it overheating. Would the things i adjusted cause overheating if they were not adjusted correctly?

Also i have a mallory unilight distributor and have not put a ballast resistor on it yet how important is the resistor and can i drive 100 miles with it not being on? I have it just have not had time to put it on yet.

 

It sounds like inadequate coolant and/or air flow at low speeds or low RPM. Are you using an electric fan setup?

 

I have a flexlite fan it think its called. Everything is new on the car except the radiator but i had that cleaned out and checked for leaks and everything came out being ok on that.

 

ttt

 

What size is the flex fan? It should be about an inch smaller than the radiator shroud opening.

I ran into an overheat problem with my '71 T/A when I first got it. A previous owner had installed an aftermarket 17" fan and it would overheat when the car wasn't moving much. I found out that the factory fan was 19.5" and eventually found one in the salvage yard. That made ALL the difference!

Does the water pump have the stamped steel impeller or the factory style cast iron? Rebuilders have been substituting cheap stamped steel impellers on Pontiac water pumps and its causing engines to overheat.

If your Firebird isn't originally a 400 or A/C equipped installing the baffles that go from the top of the front bumper to the radiator support may help. These prevent air from bypassing over the top of the radiator support. They are reproduced now and I think they are under $100.

 

The fan is the same size as the stock fan except the stock fan has bigger blades and only has 4 blades the flexlite has 5 blades. The waterpump i dont remeber what the impeller looked like i just remeber it was made by PMG i think its called not to sure on the name and it ran me 100 dollars and it was cast iron. Do you think switching back to the stock fan will help i had it begin to over heat at idle last night while i was standing around talking.