[blykins]

I sorta disagree with the prognosis. Yes you filled the surge tank, hoses, and radiator....but when you fired the engine, the water pump should have sucked it out of the radiator into the engine block. Of course it waits in the block until the thermostat opens and it returns to the radiator to cool.

I think what happened is that you just didn't have enough coolant in there at all. The level was way low...and it was just inefficient at cooling the engine down.

You don't have to "remove" the thermostat....just leave the cap open and watch the level. When it goes down, add more. You can't add too much. It will puke it out to the overflow bottle (and on the ground) if you put too much in.

I agree with Ernie...if you're using aluminum heads, check them for straightness. It's easy to warp one with high heat....and check your valve seals as well.