why not run a 195F thermostat
 

been enjoying my car on the rare day we don't have rain lately. And noticed that when
I come off a highway run and the water temps are 190, that she idles smoother and feels
more responsive. Car never gets to 190 unless temps are 80 or better.
Usually around town she hangs at 183-185, so no big temp difference.
But I started thinking, why not run a 195?

Gerry

Why not. I assume that the original 180 F theromostat is an average solution for running in any climate from Arizona to Maine and it might run a bit colder than supposed to if you live in a colder area. Check your temp gauge so it reads correct though. ( its not overheating until the idiot lights comes on at 240 F;) )

195 is a safe temp for an engine. Many manufacturers use that thermostat in modern engines. Boiling is 212 degrees f and that is with no pressure in the cooling system.
As A.J. posted with a normal radiator cap (15 psi) the boiling number is closer to 240 degrees and you are asking about a 195 degree engine coolant temp. No worries and if the engine likes it , listen to the engine.

Told a Big Boss at my old job one time, "The Engine is TRYING to tell you something, are YOU willing to listen?" Dead quiet in the room for about a minute and the Big Boss said, "Yes I Am" and we had a successful engine program. Never got fired for telling the truth in 39 years but not everyone was as smart as that guy was.

Tom V.

Hum?
 

If 5°~7°F makes the engine run that much better....Need to be checking the tune-up. Hotter combustion chamber temps and the fuel mix lights off better/easier.

So might need a little more initial timing or idle mix leaned out just a tad.

Clay

T-stats are kind of counter-intuitive. The higher the T-stat temp, the longer before it opens letting the coolant in the radiator stay in there longer, letting it cool more. Running a 160° stat will usually increase your temps because it will be open most of the time not letting the radiator do it's job. Try a lower temp stat to raise your temp a little. As stated above, you need heat to get proper combustion efficiency.

The whole purpose for running the lower (180°F) thermostat for most guys is that they are pushing the limits on static compression and can't run warmer temps. Then some guy reads that lower temps are better and the next thing you know the entire Pontiac Community thinks their car will self destruct at any temperature above 180°F..........Just like the self destruct feature at 5600rpm and 9.6:1 static compression ratio.
The '72 Pontiac Service Manual specifies a 195°F Thermostat.

It's the other way around. It allows the water to stay in the engine longer to get warmer.

Stat temp
 

Well I feel carb is set right. Same plugs look great for
A few years now. Timing is conservative at 12 initial and 20 mechanical
All in around 3200 rpm. Ported vacuum gives another 12.
Runs great as is and just thinking aloud on this one
My engine just seems happier and smoother with 180 rather
Then a 160. Maybe the fuel
Atomizes better. My crossover is open and even after a highway run
She cools back down to 182-3 after a few miles in the heat.
Just thinking aloud.

Do what?
 

If a cooling system is functioning properly, a cooler thermostat will not make an engine run hotter. Thermostat sets minimum engine operating temperature. Doesn't matter what radiator temps are as long as everything else is working right. Working right the water exiting the radiator will be cooler than what goes in. Then the thermostat will open or close to keep minimum engine temp where it's suppose to be.

The OP's car heating up at highway speeds...tells me something in the cooling system needs a little TLC.

Clay

Different temps
 

When I ran a 160 my temps were 165-170 on highway.
With a 180 my temps have been 182-190. 190 was max on long highway
Run in the heat. So I feel cooling is adequate. Heck that is why I wanted
To see if anyone else runs a 195.
Gerry

:huh:

Maybe..But
 

Might be worth a try if the engine likes the 190° temp.
But, my biggest fear would be gaining the additional 10° (on the highway), with the 195, that you had with the other two thermostats mentioned.

Don't know what compression you're running, but 205° temps might get you to the point of detonation.

I'ld have to try bumping initial timing up some and see if it runs better. Depending on your highway cruise RPM vs. centrifical advance...the engine may even run cooler.

I'ld have fun with it tweaking all the same.

Clay

The 400 in my car is out of a '69 Firebird (for comparison to the OP's setup.)

I run a 195 thermostat, (what it left the factory with), and find that my motor runs better at 200.

Old wives tale. Simply not true

This. If your engine runs hotter when you put a colder T-stat in, something is wrong.

For max power you want a cold intake. Colder/denser charge = more power. However, we're not driving around at full throttle all the time. As this is the street section, drivability is important. A warmer intake helps keep fuel in suspension giving a more homogeneous air/fuel mix that will burn better at lower RPMS/intake port velocities and hotter cylinders promote more complete/efficient combustion.

I run a 180 stat in my street cars. Good compromise between keeping things a little cooler for more power yet warm enough for good drivability.

My Formula never ran above 190-ish with a 180 T-stat in it (Needled hovered either side of 190 depending on air temps and how I was driving the car). The only time the gauge went above 195 was when there were problems.

To the OP - if I was you I'd try dialing in a couple more degrees of advance just to see what happens. Could be the engine will run cooler on the freeway. If it runs a little cooler and you don't get any pinging, try another couple of degrees. I wouldn't go over 36 total, but you might see a difference going more than 32. Or, you might not. Only way to tell is to try it. If you find it runs cooler on the freeway but you get pinging driving around town you could also try finding a vac can that gives more advance.

I'd also install a 180 thermostat. IMO, 160 is just too cold for daily driving/around town.

Thermostat
 

Currently running a 180 superstat. And after reading about it will leave well enough alone.

There should not be really any difference between 180 and 195 but for full throttle power!

I would say the better running you have with higher motor temps are due to your cruse air to fuel ratio being too fat, and or your spark plugs you are running are too cold!

Another possibility since you did not post up if the motor has been rebuilt or not is that the higher motor temps on a high mileage motor will close up the ring gaps and make for more even and higher cylinder pressure and in turn even more engine vacuum!

Temp?
 

Well the motor is the original 68 400 with 16's large valve.
Factory iron intake and long branch manifolds.
The cooling system is an aluminum rad with 2 rows of 1" tubes.
AC pulleys, severe duty fan clutch with 7 blade AC fan.
Water pump is 11 bolt, cast impeller with tight clearance to divider plate.
All filler panels and seals in place.
Plugs are R45S and same set are clean for years.
Motor was rebuilt 12 years ago. All stock except for TRW forged
Pistons. Running the 068 cam. Non AC car.
Gerry
She is just a cruiser and mostly does shorter trips.
That why I thought of higher temp. Once it gets to
September it barely even touches 180!!
Again thanks for the replies

Make sure the idle speed screw returns firmly against the stop with choke off hot. It may need more return spring
Make sure the mechanical advance is coming back to zero at idle in and out of gear. The mechanical advance may be sticking or have weakened aftermarket springs giving erratic idle.
Hot fuel pump pressure would be another check. Be careful off fire.
Confirm the above then adjust mixture screws and throttle stop @ off the highway temp.
And leave the 180 as is.

An engine is thermally more efficient at higher temps, if it can stand it. Cars from the 1980's to present are set to run at about 220 degrees coolant temp for greater fuel economy and lower emissions. Our old dinosaurs are more prone to detonation at that temp, so 195-ish would be ideal. All things being equal, an engine running at 195 will be more efficient than one running at 160-180. I also agree that what was said earlier about installing a lower temp T-stat to raise operation temps is simply not true. Just the opposite.

I prefer cooler rather than hotter. But I build and tune things on the edge for the pump gas available (which isn't that great to begin with) and running the engine a little cooler helps me deal with that a little better.

I also prefer it cooler to help fight/avoid any possible vapor lock issues during the summer months. Especially on my stock mechanical fuel pump cars. The hotter the engine, the hotter things get under the hood. I don't like seeing anything remotely close to 200 degrees on any of my classic cars.

With proper jetting, timing, and a good functioning cooling system I have no issues with the cars running in the 180 range even on the hottest of days. Just yesterday it was 102 degrees up here and the Z never got over 182-183 degrees shooting it with a temp gun. That's with it's original 48 year old radiator. 11:1 compression on pump gas with iron heads, I'm not even going to entertain a hotter thermostat in this thing, lol.

My bird always stays in the mid 170's on days like this with a Griffin radiator. They are calling for 105 degrees up here today.

I think it's just going to depend on a lot of factors. If we had the gas quality now that we had 50 years ago, or if I weren't tuning/building on the edge, I wouldn't be so concerned with it.

Like the OP's my car really starts to come to life at around 195 degrees. I run a 180 stat and most of the time it sits at 185. On very hot days it will climb a bit to 190ish and as that temp starts to come up, pretty much everything about the driving experience starts to improve.

I'm running the FiTech efi on a KRE headed 455, so I attribute some of that to probably not running enough advance for my altitude and the 88 octane that I run through it. I haven't gone about changing it however as I have no desire to run the tune on the edge. I'll gladly give up 10-15 hp to know the motor is in a good margin of error.

If I ever change intake manifolds or need to do some maintenance to the cooling system, I'll probably change to a 195 stat however.

timing
 

had off today and went out early to tinker in the garage.
inspected weights in HEI and lube(they moved free and cap and rotor look ok)
adj initial timing to 16, that plus 20 mechanical put me at 36 @ WOT. still
have 12 from vacuum can on ported source. Curb idle increased after initial
was raised, so I reset curb idle back to 750rpm as it was earlier.
drove around for 20 minutes and yes car felt smoother and more responsive, immediately.
just like when I had come off that 75 mile freeway run. Temps stayed the same
at 185(fine with that). Detected no detonation, or missing.(my curve comes in slower)
Gonna leave it this way and enjoy!!!

Thanks

Gerry

I remember when I was a kid my father explaining to me, if my cooling system was working right, once it got up to temp, it should NOT run hotter on the highway, or cooler on the highway, or hotter or cooler ANYWHERE ... it should maintain the normal temperature in all situations within the range of the thermostat open and close range.

If temp goes above the normal range ... then something is wrong with the cooling system or it's not up to the task. If it goes below the normal range, then something is wrong with the cooling system.

Just like your house ... even if you have a REALLY POWERFUL AC ... it should still not get colder than the thermostat setting, nor hotter. If it does ... something is wrong.

Exactly.

The best description of engine cooling I ever heard was:
"The radiator sets the maximum temperature and the thermostat sets an artificial minimum temperature. It just happens to be above the maximum."

Which basically means in a well functioning cooling system on a properly tuned engine that without the thermostat, or if its stuck open the engine temperature should always go down. If it's going up, then the radiator's ability to cool has been exceeded, aka the maximum is going up.

Newer car computers (ECM) monitor the time it takes from a cold start to running temperature, if it takes too long, or does not reach temperature in a certain time span, it turns the "Check Engine" light and it will have a code P0128. Usually caused by a thermostat stuck open, or the seal allowing coolant to flow when it is closed. With a properly running cooling system, the thermostat just dictates your running temperature.

My 461 had a 160 thermostat when built. I went to a 180 and it burned less oil and ran much better at full temp. Then I changed to a 195f recently with a bad ass electric fan and a FlowKooler water pump, my engine really sings now. It loves the hotter temp, better mileage, better acceleration, better idle, burns hardly any oil, and just sounds more precision in operation if that makes sense. In my mind, I'm more comfortable running a hotter temp with full forged internals as well so I know everything is expanded optimally. I also like that with an electric fan, she gets up to full temp much, much faster.

I have 670 iron heads, 9.9cr, and run 91 octane (which I *think* is 10% ethanol here in CA?). I have a mechanical advance MSD RTR dizzy with 38 total timing, never have had a sign of knocking running 91. With 87, heck yeah. Even when 112f outside and fully heat soaked in traffic, my temp gauge never goes over 220f. I have my fan set to come on at 210 and off at 198. On average she runs about 205-215 according to the gauge.

I have a Holley 4150 with a 1/2 wood spacer on a Torker II so no heat passage and I have a divorced water crossover, I never have any hot start or fuel lock problems, ever. With the Edelcrap carb and performer intake I had vapor problems all the time, even when outside temp was only in the low 90s!

Could of swore back in late 80's early 90's I bought a 205 thermostat but haven't seen them since