69 Firebird overheating

Have you tried back flushing your radiator?

What thermostat are you running?

What does "New 3/4 block" mean?

Is your temperature gauge correct?

You might try a new radiator cap.

Good luck

Make sure you still have the factory cooling fan. Many of the aftermarket fans are too small. The factory unit was around 19 inches in diameter.

Since pre 1972-1/2 Pontiacs don't have a coolant recovery tank and the radiator can only be filled to about 80% the car will run hot at idle. My '71 will sometimes get up to 210 degrees at idle.

shroud in place and good condition?

Thermostat???

My $.02

Dan

Did you replace the fan clutch? Assuming your car has a factory clutch fan.

Are the replacement pullies the correct ones for the engine?

Did you attempt, with the engine cold, to fill the radiator with the engine running? Full level should be roughtly 3 inches from the top of the neck. Charles

can't really add anything new to the suggestions. but 220 is far from overheating. It might run hotter than you want it to but it won't ruin the motor or anything. All aboard the Yankee express, next stop October.....

220 at idle is high. It is over normial operating tempiture outside of bumper to bumper 105 degree weather traffic. Charles

Its pretty normal for a Pontiac engine with stock cooling. The water jackets on 400+ cu in Pontiac blocks are somewhat small due to the fact that the block is the same size from 326-455.

IF THATS CORRECT THINKING THEN WITH THE SOURCE OF HEAT CLOSER TO THE COOLANT IT WILL ABSORB MORE AND RUN COOLER.CHECK THE TIMING.RUN IT AT 10* ADVANCED AT IDLE AND SEE WHAT HAPPENS,