I installed a 160 degree thermostat in my 70 Cutlass S. When I drive the car I notice the temp getting up to 200-210. is this normal? ambient air temp is near 100.

 

That simply means that your thermostat was not the limiting factor for your engine temp. You could put a 100-degere 'stat in there (if they existed) and it would still run 200 -210.

When a cooling system has enough capacity (by design, and well-maintained), then the engine will run right at the thermostat's rated temperature, except under the worst circumstances. 100-degree ambient temperaure is getting close to "worst circumstances." So I tend to think your cooling system is working pretty much as it was intended to.

However, if that ambient temperature is normal for your area, you might consider adding cooling capacity to your system so you can lower the operating temp. Installing a larger radiator is probably all that's needed. "Larger" meaning more tubes and/or more fins.

 

Lady seems to run that in 100*+ weather with a 180 stat and 3 core aftermarket rad. It takes a while to run that hot, but as soon as the temps drop about 10*, it is back towards normal.
Since the car was designed for a 195* stat, 200-210* does not seem like a dangerous level. (At least that's how I see it.)

Checked the Caddy today when i got home from a 20 mile stop and go drive, 104* ambient, A/C on 77*. Temp at the thermostat housing was 208; hoses for the radiator were 206 and 196*
Dash temp gauge was right in the middle.

 

My temp also runs in the 190-210 range. Since it takes it time to get to 210 on even the hottest days and never gets above 210
I consider it normal.

 

at that ambient temp, 200-210 would be normal. the idiot light comes on at 252 degrees.

I've seen 230 on a 110 day during extended stop and go traffic with the ac blasting. that's when the fan clutch kicks in and the temp goes down

 

My '50 (425) seldom got to 150° until I put a restrictor in it. Not something I would recommend doing to a street driven car.

My '50 (455) has not gone much over 180° because it has a 180 thermostat.

My '65 (330) did not go over 150° (In Mojave, CA on a 110+ day) because it did not have one. Now it does not go much over 180° because it has a 180 in it.

My '70 (350) has not gone much over 180° because it has a 180.

My '87 (307) has whatever came in it, so it will pass its bi-annual emissions test, and the temp light never comes on.

What any of this has to do with your question, is beyond me.

No.

If your 160° stat is working properly, your engine temp should easily stay under 170° on a 100° day. Factory used a 195 in your '70 so temps would stay near 200° in order to meet emissions standards.

Easy to test a thermostat: Put it in a pan of water. Heat the water. Note the water temperature when it is about half open.

At idle? Stop and go? Constant 25 miles per hour? Highway speeds? Or any combination of the above?

Norm

 

I was out cruising today, and coolant temp was running just below 200, high ambient temps are a killer..