Got a 77 F-250 that overheats. Removed the thermostat, replaced the radiator, backed the timing off as much as possible, still starts to cook after 15-20 minutes. (Did a chemical flush before replacing radiator). Any Ideas? Thanx.

 

Strange as it may sound, the lack of a thermstat can make the water flow through the block so fast it don't pick up the heat it should and get it out to the radiator where it is dissipated into the air. you might try putting in a 160 degree thermostat and also check the water pump to make sure the inlet hose to the pump ain't collasped on the inside and restricting the flow of water to the water pump itself. also make sure the belt is tight on the pump/fan and if the fan has a clutch, make sure it is working too. worse case, the water pump may just be worn out and ain't pumping enough water through the motor.

 

like I say roundman Said in in those perfect words

 

Correct about the lack of thermostat. With a thermostat in place the flow is restricted/slowed down enough that heat transfer is able to take place. Shoot the coolant by too fast and not enough heat transfer takes place.