[Longs]

My car's an A/C car, original 335 HP 400 4 barrel, I have a Desert Cooler radiator and the factory clutch fan setup, shroud, etc.

As I mentioned in post #1, I had a 180 degree thermostat installed. It would run up to 195 or a little higher on a hot day driving around town, it may get to 210 on a long highway drive on a hot day.

I ordered a 160 degree high flow thermostat from Amazon. It was listed as a Stant Super Stat part number 45356, but I received a MotoRad 2000-160 high flow thermostat. MotoRad purchased Stant some time back, so is this really the right part number, or did the supplier just substitute the equivalent? I don't know but I decided to keep it.

I removed the 180 and tested it and the 160 in a pot of water on the stove. The 180 opened right around 180 and seemed to be fully open by about 195. The 160 opened right around 160 and was fully open by about 175. The 160 high flow definitely had a larger opening than the 180 that was installed. Both were functioning as expected relative to rated and fully-open temperatures.

I installed the 160, nothing else changed from the 180. I took the car for about a 10 mile in-town ride with a brief stop in the middle. The outside temperature was 78 degrees so not real hot but not cold. The car never got above 180 degrees, so I DID realize a 12 - 15 degree reduction in running temperature compared to the previous thermostat. Even if the car runs 10 or 15 degrees hotter on a really hot day or on a long highway drive, it will still be a clear win.

In my case, the thermostat appears to be the determinant of the operating temperature, at least going from a 180 or a 160, the thermostat was the limiting factor.

Relative to the other responses, do I believe that on a 90 degree day, a typical car with a 180 degree thermostat will run at 180, rather than closer to the "fully open" temperature for the thermostat? No. Do I believe that's much more likely on a 10 degree day in the middle of winter? Yes.

I'll report back when we get up around 90 degrees, which should be coming later this week.