Another Overheating Mystery

[Oregon 1967 GMC]

Originally Posted by SRU1436

Are you reaching these temps while idling or driving? Is the AC on or off when you reach these temps? What kind of fan you you have? Fan shroud? How big are the cores on the radiator? I had the same problem on my chevelle after AC install. The AC condenser blocks a lot of air flow, it should be (I believe and if I remember right) based in vintage air directions about 1.5 inches away from radiator. My fix was add a HD fan clutch to my mechanical fan.

Idling and driving
AC on and off
Clutch fan with shroud half in half out as direction say.
I'm thinking some air possibly left in system and tired water pump.