This is a direct cut and paste of an identical post I made in another forum on this board, at the recommendation of another member:

Hi all,

I'm really a dodge guy, but I've been working on a '74 [font=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif][font=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif]ford[/font][/font] dumptruck for a buddy of mine. Here's the scenario: The truck supposedly came with a 361, whereabouts unknown now. I'm told it has a 391 in it presently.

It popped a headgasket and made a milkshake in the crankcase, so my buddy pulled the heads and sent them off to be milled flat and checked for cracks. I came into the picture after he got the heads back-I put them back on, and reassembled the rest of the top end of the engine. It now runs fine, except that it overheats after running for a while. I'm beginning to think that it ran hot in the first place, then blew the headgasket. If that is the case, whatever caused it to run hot has apparently not been fixed. Both [font=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif][font=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif]thermostats[/font][/font] (it has two in one housing, side by side) have been replaced. Upon discovering that it still overheats, my buddy removed one thermostat and drilled holes in the other to improve [font=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif][font=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif]coolant[/font][/font] flow. That did not fix the problem.

He asked me whether I could have put the gaskets on backwards. Thinking back, I remember paying attention to that, and I'm pretty sure the gaskets were labeled "front" on one end of each. I also think I remember making sure the gaskets were installed correctly based on the fact that they were labeled. I'm not even sure the ft motors will overheat if the gaskets are put on backwards, but I didn't want to take chances.

The [font=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif][font=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif]radiator[/font][/font] is not obviously plugged, either internally or between the fins. I have not personally driven the [font=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif][font=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif]truck[/font][/font] enough to tell whether it is overheating at low speeds, high speeds, or both. The static timing is set about 4 degrees advanced from spec, which it seemed to like. Also, the plugs look bone white, which would indicate to me that it could stand some mixture richening. The thing is, I don't see that making it run hot unloaded, which it is. What ideas can you guys come up with?