[71 T/A]

My 72 Formula 400 is stroked to 455 with Stump Puller 230/236 HR cam. Includes SD Performance ported heads, ram air exhaust manifolds with 2.5" pipes, 3200 stall Continental converter, 3.08 gears, Griffin radiator, clearanced water pump plates, 160 degree high flow thermostat and stock clutch fan.

Car will run 110 degrees in 40 degree temps we're having in North Carolina and will go to only 140-150 in the summer with a/c on. Is that a problem?

[JLMounce]

That may or may not be an issue. It really depends on how hot your oil is getting. You need to get the oil above 160 degrees so that is evaporates any condensation it may be holding. Otherwise you can literally start to rust the oil itself as well as anything sitting in the oil (crank, bearings etc.)

I have the same problem with my engine in the cold months. In 40 degree weather I can't get it above 120-130, even running 3200 rpm on the highway. I as well have one of those high flow thermostats and I believe they simply allow too much flow, too quickly in their opening to keep the engine at temperature in cold weather. I'll be changing mine out to a stant super stat this spring.

[leeklm]

As mentioned, install a "regular" Stant thermostat. I would install a 180 and if that keeps you below 195 or so in the hotter summer months you should be in good shape all year.

If it seems like you are not getting enough coolant flow in the dead of summer, try the 180 high flow.

With your combo and cooling system I doubt you will have any issues

Sent from my SM-G965U using Tapatalk

[Half-Inch Stud]

sounds like the thermostat was left out. I used to do that with the Hi-compression 455s and realized the cooling system can over-achieve. Thermostat a good thing.

[71 T/A]

I'm using one of the Stewart Components 160-degree high flow thermostats with the 3 holes drilled in it.

[Formulabruce]

IR gun to Thermostat housing. Do Not trust the factory gauges

[Chief of the 60's]

I'm going to say the gauge and/or sender is bad. I have never seen a warm engine only do 110 degrees and I grew up in Buffalo!

[steve25]

X2 with the above IR gun check out for sure!
If that 110 is correct your going to experience a lot more ware then normal .

Pistons will not expand the needed amount, nor will ring gaps close up, making for added blow by.

Even bearing clearances will not be what they should be, and if your oil temps do not get above the boiling point of water then condensation which is laden with a certain amount of acid from the combustion process will slowly eat away at soft metals in the motor like what a large portion of what bearings are made of.

With oil temps above 212 degrees that condensation turns to steam and gets drawn back in thru the PCV system for another burn session .

Your cooling system and water pump efficiency and general tune should allow you even on hot summers days to run a 180 degree stat which is what I consider normal for a hi po street motor.

If your coolant temps do not get up to 180 degrees
After 8 to 10 minutes of street driving at 30 mph then things need to be looked at, as
Even that will add to elevated levels of ware!

[JLMounce]

Originally Posted by 71 T/A

I'm using one of the Stewart Components 160-degree high flow thermostats with the 3 holes drilled in it.

Those holes are likely part of your issue. Those holes are there more specifically for some of the chevy engines which don't have a bypass built into the water pump, the thermostat can act as a bypass in that situation.

What that's causing for you is that even when the thermostat is closed, you're circulating coolant through the system. Enough so that the thermostat is failing to properly regulate temp.

More than likely, replacing the stat with a non-balanced stat like the Stant Superstat

[Navy Horn 16]

Originally Posted by steve25

With oil temps above 212 degrees that condensation turns to steam and gets drawn back in thru the PCV system for another burn session .

Oil and engine temps don't have to be anywhere near 212 degrees to get the condensation out of the system.

The system is under a vacuum, and water doesn't have to reach anywhere near 212 to change phase to vapor and evaporate. 212 is the point at which inter-molecular bonds of water are all broken (at atmospheric temp), that's boiling. Phase change (evaporation) happens at room temperature and even below freezing (sublimation).

At the molecular level, the oil in the system is going to be put under a strong vacuum at the pump inlet, which would serve as moisture separation, and certainly cause a phase change when that molecule hits a piston ring or other high temp piece of metal.

Someone has to have MAJOR water intrusion issues for this to be a factor. Running a cool motor isn't going to cause water build up in the lube oil.

[Radman]

Your summer temperature's say either the thermostat opens to soon, or the gauges read low. Old cold weather trick is to take a sheet of cardboard and block the air flow to the lower half of the radiator. My 2019 GMC truck has the venation blind style air control in front of the radiator.

[71 T/A]

I recently moved from South Florida where the gauge would read 160 in the summer with ac on and long idling. Even there in Florida, the top radiator hose would feel much cooler than other Pontiacs I've owned. I'll be replacing with a Stant 13008 180-degree T-stat.

On an important side note...when I bought the car in 2009, the water temp gauge read 220 and the top hose felt just slightly warm. I replaced the water temp sending unit with a Lectric Limited one. Temps on the gauge dropped to 140-160. No other changes. I highly recommend everyone to check this company's water temp senders as they are correct for our cars according to the company.

[Formulabruce]

Keep in mind the windings on the gauge its self can wear and change the resistance in the coil and the deflection of the gauge.
Pontiac/GM had a one sheet on these gauges. It said they are only good to +/- 5% . This is why we ( the techs ) called them "glorified Idiot Lights"
On Complaints we were told to Always screw in a manual gauge to the intake at the T stat housing area. We test drove cars around with that gauge connected.
I have "tuned" a few older gauges with resistors in the sender line to match the gauge to the IR gun reading. ( this requires some math and trial and error) . This does work, but it slows down the gauges response to changes.
The temp gauge is just a Volt meter, and the sender in the intake/head is just a gradual ground. Hotter it gets, more it grounds and higher the voltage ( temp) reading.

[JLBIII]

I had the same problem with my 68 Firebird. Rally pack temp gauge only went 1/4 way up. Talked to Pete Serio about it. He told me that is normal for that gauge and that the engine temp is about 180. The halfway mark on the gauge is 210+. I got an IR gun and confirmed that my engine temp was 180 when running with the gauge at the 1/4 mark. Pete also talked about the sending units themselves. Before there used to be many different units now there's only one or so that has about 10 different applications so while it works it may give a more general range than specific.

[Cliff R]

The last time I looked it was 2021. Not sure why or how someone would run a 160 degree stat in one of these engines unless the build is just messed up enough it climbs up past 210-220 degrees on a nice cool day.

For well thought out engine combo's you'll find more trouble getting heat into it than removing it.

I would get rid of the 160 stat and go to at least 180. Heat is your friend with these things despite the fact that folks have been telling us for decades to run these engines too cold........Cliff

[grandam1979]

Put a 195 stat in it take it for a ride see if temp comes up on gauge. If it comes up to 160-170 you know your gauge is off if it goes to 195 you know it’s the other stat. Auto Zone has the cheap aftermarket temp gauges for about $20.00 that would be a cheap way to double check temp.