[dataway]

How many of you use 180 degree thermostats or 195 ?

I'm leaning toward 195 as specified originally. I assume if my cooling system is operating properly it should not go over 195, which is fine to me unless someone tells me otherwise.

It's 68 AC car, and the AC probably will be getting used. Stock engine.

Anyone know what temp triggers the idiot light switch?

And .... why is the freakin hole in the thermostat about 1" ID while the hoses would flow about five times that much?

[tom s]

OK,have to be diff,I use 160.Tom

[dataway]

Does it actually run at 160? Or settles in somewhere higher?

[tom s]

my 62 GP runs at 160,so does my 69 455 bird.Tom

[tooski]

I used a 160, but engine ran at a steady 175.

[PAUL K]

160

[tekheavy]

160 here too. Runs between 175-185.

[Kenth]

195°F with 10W30 is a perfect match.

Running a 160°F thermostat plus heavier oil looses power and increase engine wear and reduce fuel economy.

I have found no reason not to follow recommendations in the Owners Manual.

Idiot temp lamp turns on at 245-250°F.

FWIW.

[STEELCITYFIREBIRD]

I run a 180..and drove guys in the staging lanes crazy as I idled my car to keep it up on the thermostat. Consistent temp, heat soak makes for consistent passes.
I need a 180 or my heat is meh.

What compression ratio did you end up with? Time will tell if it likes heat.

[Formulajones]

Like the others, I too run a 160 in several of the cars here.

Depending on how good the cooling system is dictates whether that particular car will actually run 160 though. Plus ambient temps here in the SW desert are much higher than most other places in the country. Pushing the compression ratios, the crappy 91 octane we have out here on the West coast are just some of the reasons why I prefer to try to keep the engine a bit cooler. Been pushing them like this for 30+ years. Excessive engine wear and poor gas mileage is not an issue at all. Some of these engines have been together for 20+ years now without a single issue, and everything I have returns respectable gas mileage for what it is.

[ta man]

Another 160 user here. I have been using 160 degree thermostats for 25 plus years in my Pontiacs.

[74Grandville]

I would run a 195, but with iron heads it's hard enough to control ping. I figure a 180 stat is a good compromise


I guess this raises another opinion.

if I had aluminum heads, 195 would probably be the route i would go.

[locomotivebreath]

I’d love to hear from some engine builders on this subject , in regards to the cylinder wall wear rebate on too Cold a stat . I built an iron headed 10.1 406 , zero decked with a 280/288 bullit roller and otherwise stock cooling I.e. 4 core Harrison and stock 68 flex fan . Should I start out with a 160 and go from there ? I’m just assuming a 195 will cause detonation . What has been other experiences ?

[Roadking88]

160 for me in 3 cars. The only with mechanical gauge says it runs 160-165. Would buy another 160 again.

[Chris65LeMans]

I run a 195 with iron 96 heads. This question is just like “what oil should I use” or “what color should I paint my car?” You’ll hear everyone’s opinion, and just have to come up with one of your own.

[locomotivebreath]

^^^^^ that’s why I’d like to hear from experienced engine builders and such . Was sludge an issue from running too cool ? Experiences on the dyno such as different bsfc etc .

[Formulajones]

Never had any sludge type issues at all. I feel that issue is more related to the oil you use, how often you change it, and whether the oil has a good detergent package.

If we still had 100 octane at the pumps like we did 45 years ago, I probably wouldn't be so concerned with engine temps and cylinder pressures. If I weren't pushing the pump gas envelope with the crappy pump gas we have now, I also again, probably wouldn't be worried about engine temps and cylinder pressures. I'm the type of street guy that will build the engine to push what I can out of it with the given pump gas we have to work with. Others just want the engine to run and get from A to B with little concern how much power it makes, some even want to run the cheapest gas they can find. As long as it idles smooth and makes vacuum most here are happy. Those types of engines probably don't care how hot they are running.

Everyone will have a different situation.

[dataway]

Yep, collecting opinions.

Mine is an iron head (16), right at 10:1.

In the past I've run 180 for the simple reason that it gives me more head room should something be amiss. ... If the cooling system is working the way it should, the temps should be no higher than 180 ... if it goes higher, you know there is a problem. If I start with 195 and something is amiss .... it might be at 205 before it become very evident. Less time to do what you have to, to get things cooled down.

But ... I imagine the radiator works pretty good at 195, the higher the Delta T between coolant and air temp, the more efficient the heat transfer. My guess is the OEM radiator is designed around an average temp differential that includes 195 degree coolant. But lots of people don't run original radiators now. Coolant formulas have probably changed also.

I think I'll start with a 180 and see how it behaves.

[ponchjoe]

180 with an aluminum radiator

[Formulajones]

Experiment with it. If it's a 10:1 iron headed motor, then engine temp is definitely something I'd pay attention to. 180 may work fine for you. Tune up, the pump gas quality, and the camshaft (cylinder pressure), rear gear, trans, and weight of the car all play a roll.

There are a couple of mine here that I run a 160 in but the car doesn't actually run 160. One example is my 69Z, it has it's born with date coded radiator, a copper 3 core, and completely stock cooling system, clutch fan, shroud etc... It's an 11:1 iron headed motor I'm running on pump. Engine temps run right at 175 degrees most of the time. Throughout the summer when ambient temps here were over 100 degrees the engine would run in the low to mid 180's, which isn't all that bad really. The only time I've seen it run just under the 170 range is early morning cooler temps.
Basically this cooling system just isn't capable of keeping this engine at or near 160 when ambient temps are in the normal daytime range here. But hovering around 175 works in this case. However it's certainly not an engine I want to force to run at say 195 with a 195 stat.