Ahh. My two cents.
I run a 185 in my truck. I like the 185, as it makes more heat in the cab. It has dual carbs, doesn't get more fuel, just better mixture. I have a zero pounds radiator cap. Even running with a load, in all the heat we've been having, it never overheats, it never actually moves from 185.
I would suspect, that as stated earlier, the rad is over filled, and pukes out the excess, as the coolant expands. I know thats what my truck does.
If your carbs are lean, your truck will overheat. But that's a different problem.
Get that thermostat in there, and then see whats what.
