What thermostat to use, 180 or 195 ?
 

What temperature thermostat is every using in their 1960's and 1970's street driven Pontiacs ?

I use a 180 in the 37 in my signature.

180. Whatever you decide test in a pot of go water first to learn where it opens- some open 10-15 degrees past the rating

With real gas, a 180. With the e10 piss, a 160. Lots of issues down here about fuel boiling out of the vent tubes. So, I try to keep the engine, under hood air, carb as cool as possible.

IMO, a 195 is too hot for an engine with a carburetor, especially running E10. 160-180, Trial and error. A really good radiator and fan will keep a 160 thermostat engine running around 170. About 190 with a 180 thermostat. If the engine runs good with a 180 thermostat you will get slightly better gas mileage and keep the spark plugs cleaner at long idle/low speed driving.

180 and a good cooling system has worked for me (clutch fan, 4 core copper or 2 Core alluminum radiator and proper tune.)

195 you'll probably fight Detonation.

I use a 160 in everything. Which means typically they'll run in the 170 range on a really hot day, which helps to keep me out of detonation and away from vapor lock issues with todays gas.

On a cooler day, say 70 degrees or below, I generally see it operate closer to the thermostat rating.

I run a 160 in everything, and drill a small hole in the base of them to help bleed air/prevent air pockets.

195° F, 10w30 mineral engine oil and 50/50 glykol/water, just what the service manual calls for. Not an issue in 25+ years.
Note: Too low engine operating temperature increases wear and looses power.

FWIW

I haven't found that last statement to be true......with my stuff anyway.

I've been running these 160 stats in several of the classics here for going on 35-40 years. I've never had any excessive wear problems. In fact 2 of them are daily drivers that have seen over 100k miles combined in the last 5-6 years and they still perform perfectly :noidea:

At the track we've found our best ET and MPH when the car is cooled to about 150 to start the run and generally is around 165-170 when finished. Hotter just slows the cars down so I don't see the loss of power with the cooler temps either.

I totally agree. In my years of experience in racing. Temps above 180 slowed the car down. I would be forced to soften my dial in during hot laps. I also run 160 thermostats and had zero issues with excessive wear.
If ones car is strictly a street driven car and for some reason the owner likes to drive it in cold winter conditions then I would put in a 180 so the heater would work better.

Yep. Same here. No problems with engines running 160`s. Street drive em in the summer here with a hot thermostat? Good luck.


Mostly, you will get to where you`re going. Coming back? That`s another story. [Hot soak]

160 degree thermostat for years.

Yep, racing in Phoenix especially.

I've run my bird the most there, and in early rounds with enough cool down time I can run right on my dial where the car has run it's best time, but once we get down to the last 6 or 8 cars and time shortens between rounds I have to dial it back from 13.10's to 13.30's because it just won't run the number when the engine gets that hot.

If you use the typical drag strip slide rule for HP, that's a significant drop when the engine heats up.

I always have very similar results with the other cars as well.

160 with distilled water and a bottle of water wetter.Tom

When (and this may take a while) I get my car to a street reliable setup (a working PCV system, Vacuum advance, mechanical fuel pump with a regulator, electric fan vs clutch fan setup sorted out) I'm going to experiment with a 180 and 190 degree thermostat and see which one works better. Thermostats arent that expensive so I'm just going to try it out.

I’ve also found that 160 works best for all around drivability.

The other part of the question is what style of thermostat is everyone using?

Back in the 60s, Pennsylvania winters I tried 195. Then changed in summer to 160. I found out for 'myself'160 seems to be the best all around. Performance in spring and summer,fall and heat for winter. That's me.

160°F is 71°C.
Hope you´re not running 20w50 engine oil.

Reading this paper may be an eyeopener:
https://www.widman.biz/uploads/Corvair_oil.pdf

FWIW

I run basic Stant thermostats. I buy a bunch of them at a time from Rockauto. They're super cheap on there.

I like to have a stock of small parts like T-stats, housing gaskets, clamps etc etc