1972 chevy 1/2ton pickup overheating, not sure why?

[rsavage]

I would. Once you overheat a stat, it has been my experience that they no longer work as they should - it might be one of the reasons why with it out it doesn't overheat. If your radiator is new it should hold the pressure so I see no reason to get a lower pressure cap as that will only make it easier to boil. I would get a shroud, a new 160 stat, make sure the timing isn't too advanced, and not idle it in the driveway for long periods of time, as you are not going to move enough air to keep it cool.