1960 Valiant Restore: advice welcomed.

Gadabout said
Some like it hot, some not. So, I pick up Mabelliene in time for the local car show, and she starts overheating. First the temperature gauge stays normal, then it slowly climbs to overheated range, then slowly works its way back to normal and then goes slowly back to overheating.

This seems like a thermostat issue, but they tell me they replaced it when they refurbished the radiator. If not the thermostat, then what??? Is it possible the water jacket, that being the ducts for block coolant, are clogged solid, too???

Needless to say, I didn't attempt to take her to the car show.

I would get an infra red temp gun and shoot it in several places to verify it is over heating. Shoot the thermostat area, both on the cylinder head side and the radiator hose side. Shoot the top hose right where it goes into the top tank. Shoot the bottom hose where it goes into the water pump. This will tell you how good the radiator is working. There should be a vast difference between the two if the radiator is still effective. It's possible you have a bad temp sending unit, but you need to verify the temperature first.