Car still running 190⁰+ even with 170⁰ thermostat

[Juice]

I used to drive my 1979 Mustang V6 in -30°F in North Dakota. I had a 100 mile round trip for work. Even with the grill blocked off it never got hit enough to clear the inside of the windshield. Oddly, whenever it was in the 35°F-40°F range with high humidity, the carburetor would ice up.

Somewhat of an extreme example there man, lol. Not your every day usage.

 

[Laga]

It was everyday for me. The first winter I was up there, 1981, it did not get above 0°F for over a month straight. A couple of times, the high for the day was -25°F.

 

[DieHarder]

Well, Nome, AK was the coldest I've seen. Was a couple hours north at a military unit. I think we measured -65 ambient (without wind) a few times. With wind... off the scale. Used to have to put warming blankets on the tractors/loaders or the tires would freeze solid and break. When it warmed up to 0°F we'd go outside to play football. Called it the ice box.

 

[Laga]

Well, Nome, AK was the coldest I've seen. Was a couple hours north at a military unit. I think we measured -65 ambient (without wind) a few times. With wind... off the scale. Used to have to put warming blankets on the tractors/loaders or the tires would freeze solid and break. When it warmed up to 0°F we'd go outside to play football. Called it the ice box.

But we’re you driving a Mustang in that cold?

 

[Midlife Crises]

Here in Fairbanks you can tell the Mustangs and Cameros that drive through the winter because the ice and snow builds up in the front and rear bumper covers and they fall off. More than one car driving around town with bungee cords holding the rubber front or rear on.
To the OP.
I am running a 160 or 170* thermostat. With the stock radiator the temperature gauge reads exactly where it did when the car was stock. When I installed a larger, Mishmoto ? radiator with that same t-stat the temperature gauge reads noticeably lower.

 

[DieHarder]

But we’re you driving a Mustang in that cold?

No cars there. Had to fly in/out via bush plane though I suppose you could reach it with a snow mobile or snow cat if you had to in winter. The Eskimos could. Station supplies came in every 3-weeks on a C-130. Tours were 1 yr. Considered arduous duty at the time. Quite the experience. Unit closed down now.

 

[07 Boss]

I don't have to use any anti-freeze. I only use distilled water and water wetter in both my radiator and intercooler.