geegadwar

I have a 65 GTO with a 427 big block engine. It is a race car. I've had trouble for YEARS! with overheating. You name it, I've done it. I even had it rebuilt by a supposed quality race engine builder. still overheats. It has cast iron heads. A few of the things I've done( among many more) are new 4 core copper radiator. I let Summit racing talk me into a 2 core aluminum radiator, still overheats. I've put an electric fan on it, electric water pump, shroud, with a thermostat, without a stat. Moroso restrictors, various. timing variations etc,etc, You start it up and the temp just keeps climbing till I shut it off. I assume the engine builder hot tanked the block. Anybody got any ideas?

Kazoocruiser

With the engine cold, open up the radiator cap and then start the engine, and watch the filler neck while the engine runs. If you see bubbles, you have compression gas being pumped into the water jacket.

You can get a pressure tester at an auto parts store through a loan-a-tool program. With the engine off, pressurize the water jacket to 18-20psi and see if the pressure holds.