Best Thermostat Range?

[Crankster]

The truck shop manual for '64 says in specs - for all engines - opening temp 185° to 192°F and fully open by 210° to 212°F. This sounds closer to 195° being "correct" than a 160° or 180° thermostat. Did they even have 195° thermostats before the 1970s though?

Ran a 180° thermostat this past year and it was noticeably deficient in heater output in cold windy weather so I put the 195° back in.

 

[Alaska Jim]

here in Alaska we always recommended a 195* T-Stat because of the cold weather in winter. It does help with a noticeable amount of more heat coming out of the heater. Before the '70's and the emissions controls, we all ran 180* stats, but that could be because we were not aware of the 195's

 

[Crankster]

Expected a difference but it's a lot more than I thought it would be. This past spring in high winds and 20° temps on the highway, had the heater on full blast and it wasn't quite enough. These cabs aren't insulated like modern trucks of course. Normally the heater works really well.

Stant, fwiw, lists 195° as OEM for the Y block. Never had any trouble in hot summer weather, though it's possible at altitude things might be different.