How hot can aluminum heads get before they warp?

[MiracleMax]

Originally posted by Stang_ROTY:
The fan is only rated at 350HP. It could be the problem. What do you think about using a stock pulley? That would help rotate the pump quicker, right?

This is how I look at things

hi perf pump + UD pulley @ low rpm = stock cooling or there abouts and as engine speed increase the gap opens back up in favor of the modified pump.

Taking a look at things Jim might have the answer? especially since you indicated that the engine ran cooler with the stat out. I would venture to say that maybe if you have the early block with your heads then maybe the water is cycled through the system to fast to allow steam pockets much time to accumulate?

that wouldn't be a fix though, just some duct tape covering up a problem since you still wouldn't be getting the benefit of allowing the coolant in the block time enough to absorb heat to its capacity.