69 F-head running poor

i did a full tune about 2 months ago. ran great after the tune. i had a problem with it overheating and solved that with a new radiator. now today its coughing under power and getting hot, like 210-215 where before it ran around 175ish. whats the problem.

 

Those F heads had a nasty way of not vacating all the air from the cooling system and getting hot, almost all the way to "H", and then cooling down.

Assuming you got the correct size rad, and the thermostat is OK, you might try getting the jeep with the left front as low as you can get it and the right rear as high as you can get it safely.

You might squeeze the upper rad hose to see if you can dislodge any air bubble that could be stuck. Even rocking the jeep a little might make it pass.

I have gone so far as to loosen the heater hose coming from the rear of the head to try to purge the air.

Sorta like burping a baby......

good luck

 

I agree with burping, but also make sure you have a bypass hooked up from the water pump to the head.