[mrgoatman]

Help,summer is here and I have to put my 67 gto convertible up because i cannot stop it from running hot.runs reasonably cool cruising,gets very hot at highway speed,faster you go,the hotter it gets.400ci,bored .030 over,ram air cam,other than that stock.have covered all the basics,radiator,fan clutch,water pump,plate,with and without thermostat,fan schroud.hoses etc.
help!!!!! thank you.

[chiphead]

What is compression, fuel used and timing? I could suggest checking timing, then upping the octane with premium or race gas, and see if car runs cooler. Silent detonation will build heat in our engines.

I once had a 350 in my LeMans i overadvanced the timing on. Even tho the engine only had 9:1 comp and I used 93 octane, it still detonated silently. It ran very hot at high speed, until I backed total timing from 38 to 34*. Dissassembly of the engine revealed connecting rod bearing damage, which is a telltale sign of detonation.