1969 Camaro Over Heating issue

[Sauron327]

The last four "overheating" issues I diagnosed were not overheating problems at all. They were faulty sending units or gauges. Helps to have good spare gauges hanging around, or an IR gun.

[Vince]

I'm just throwing this out there as it happened to me.  My car started running hotter than its regular norm and started dying at a stop and being really hard to restart.  It usually didn't restart until it sat and cooled down awhile.  It turned out that the heat riser valve in the passenger side exhaust manifold had frozen shut. 

My suggestion is that you throw the heat riser valve out in the snow and replace it with a "donut" in order to avoid the very problem you mention.  I got rid of mine a long time ago. Only thing I do to compensate is a few more seconds at idle after starting cold.

Heat riser valves you get today from anywhere are junk IMO and you are just asking for trouble if you install one.

I agree.  What I had done was to have the flapper in my heat riser valve removed and the holes welded shut so basically it looks like it is still there from the outside, but there is no inside flapper anymore.