Correct Thermostat Temp

[Gator]

What temp thermostat are you guys running in your small block 340. Recently my mildly built 340 would run anywhere from 175 on a cool day to 185 on a 85 degree hot day then my water pump went so I replaced it along with a 180 degree thermostat and now my 340 runs constantly at 180 and on a hot/humid day will hit between 195 and 200 in slow moving traffic and when moving afterwards it will drop back down to around 180-185. I was told by another mopar guy that he was running a 160 degree thermostat and never goes higher than 180. I have no clue what my old degree thermostat temp was. So what is your guys opinion on running a 160 thermostat instead of a 180? I dont feel comfortable with it running close to 200. Thanks

 

[Ricks70Duster340]

What temp thermostat are you guys running in your small block 340. Recently my mildly built 340 would run anywhere from 175 on a cool day to 185 on a 85 degree hot day then my water pump went so I replaced it along with a 180 degree thermostat and now my 340 runs constantly at 180 and on a warm day will hit between 195 and 200 in slow moving traffic and when moving afterwards it will drop back down to around 180-185. I was told by another mopar guy that he was running a 160 degree thermostat and never goes higher than 180. I have no clue what my old degree thermostat temp was. So what is your guys opinion on running a 160 thermostat instead of a 180? I dont feel comfortable with it running close to 200. Thanks

Your 180 is perfect.

 

[Gator]

Your 180 is perfect.

That is what I was thinking but wanted to get more input from others.

 

[Professor Fate]

What temp thermostat are you guys running in your small block 340. Recently my mildly built 340 would run anywhere from 175 on a cool day to 185 on a 85 degree hot day then my water pump went so I replaced it along with a 180 degree thermostat and now my 340 runs constantly at 180 and on a hot/humid day will hit between 195 and 200 in slow moving traffic and when moving afterwards it will drop back down to around 180-185. I was told by another mopar guy that he was running a 160 degree thermostat and never goes higher than 180. I have no clue what my old degree thermostat temp was. So what is your guys opinion on running a 160 thermostat instead of a 180? I dont feel comfortable with it running close to 200. Thanks

200 wouldn't concern me too much.
Regarding thermostats, remember this:
They do NOT control maximum operating temperature. They only control the temp that the thermostat OPENS and the system begins to cool- this is your minimum operating temp. Factory calls for a 180*. Once the t-stat opens and begins to allow the system to cool the engine, it should theoretically never drop below that temperature. Actual operating temperature is more a function of system efficiency and condition (correct parts in good condition, functioning correctly), and 200* is not excessive.
This assumes a mostly stock-type engine.

 

[Dart Frog]

180 is a good performance thermostat. I like to run right around 180 Max. 200 is okay but a little high for my liking .

 

[Owen 340+6]

One of my 340's has hit 240 multiple times over the past 15 years. I have a 180 in that one with a shroud and it still runs 190- 200 down the road hits 210-220 in traffic. I would like to see less but it don't bother that old girl she just keeps rolling.

 

[toolmanmike]

Perfect. 200° is not overheating and the system is working if the temp goes down when you get out of traffic and get some air flow going.

 

[413]

Next time look at the brass center piece the temp is usually stamped there.

You can leave it or go down to 160 and see what that does.

I put 160 in some cars. If i drive in cool temps I block part of the radiator to raise temp slightly.

I don't like them over 200 ever. Just me.

 

[Inertia]

I use the thermostat to control the cabin heater temp.
160* might not pump enuff heat to warm the cabin in winter, that's where the 180 and 195* options come in, - passenger comfort.
We refered to 160* as a "summer" thermostat to aid the A/C.

 

[8formulas]

....and your other question should be: what brand thermostat do you guys use? Temp is important but quality is up there too. I always run Robert Shaw thermostats in my cars.

 

[Inertia]

I try to find the " fail open " thermostat, so a tow truck isn't needed if it does .

 

[Dartvader440gt]

My cars seem to like 200-220 in the summer heat. I have a 180 Tstat and both say in that range. It used to make me nervous but it's been that way for years. Never really hints on overheating. 65 Belvedere wagon with a mild 360 and a 67 Fury wagon with a stock 318.

 

[Gator]

180 is a good performance thermostat. I like to run right around 180 Max. 200 is okay but a little high for my liking .

Yes ditto on the 200. That is why I would like to keep it around 180-190.

 

[Gator]

200 wouldn't concern me too much.
Regarding thermostats, remember this:
They do NOT control maximum operating temperature. They only control the temp that the thermostat OPENS and the system begins to cool- this is your minimum operating temp. Factory calls for a 180*. Once the t-stat opens and begins to allow the system to cool the engine, it should theoretically never drop below that temperature. Actual operating temperature is more a function of system efficiency and condition (correct parts in good condition, functioning correctly), and 200* is not excessive.
This assumes a mostly stock-type engine.

Not stock. Pushing around 380hp

 

[Gator]

I use the thermostat to control the cabin heater temp.
160* might not pump enuff heat to warm the cabin in winter, that's where the 180 and 195* options come in, - passenger comfort.
We refered to 160* as a "summer" thermostat to aid the A/C.

I do not run my 340 in the winter plus I have no heater. Car is usally put away around mid to late October and comes back out late April. So in your opinion would running a 160 be ok?

 

[Professor Fate]

So in your opinion would running a 160 be ok?

A 160 doesn't let the engine warm up as fast as a 180 will, and will have very little effect on normal operating temperature.
A "warmed over" engine is called that for a reason- altered cam lifts and durations, larger carburetors with additional fuel metering, larger valves/ports all add up to one thing: additional fuel and air being ingested by the engine. This is what generates more power. Additional fuel and air being combusted equals more heat being generated. Additional heat means higher operating temperature. To address this, the system capacity needs to be increased to handle the added demands being put on it. Both air and coolant flow, as well as capacity, need to increase in order to dissipate the additional heat being generated. A higher output engine needs to retain some additional heat in order to properly burn the increased fuel & air volumes being forced into it. A colder thermostat does nothing other than open earlier, delaying the engine from reaching optimal operating temperature. Once a thermostat of the same type opens, be it a 160 or a 180, it is open- no difference in flow. At that point a t-stat becomes superfluous- it may as well not exist; it's purpose is done. From that point, what controls your operating temperature is the rest of your cooling system- the radiator, the water pump, the fan(s).
If you think your engine is running too warm, it's time to look into the rest of your cooling system, not try to "band-aid" it with a simple thermostat swap.
And as I said earlier, I don't think a high of 200* in a performance oriented engine is overly concerning.
To put this into perspective, a 2020 Challenger 6.2 putting out 797 hp (that's double the horsepower of your 360 from a similarly-sized engine) runs a 203* thermostat; so that's a minimum operating temperature once the t-stat opens. Wouldn't surprise me if it runs 15-20* over that normally.

 

[4spdragtop]

Remember that 100% water boils at 100/212. If youre running a 50/50 water/coolant mix that raises the boiling point beyond 100/212 significantly. You're fine.

 

[Inertia]

I do not run my 340 in the winter plus I have no heater. Car is usally put away around mid to late October and comes back out late April. So in your opinion would running a 160 be ok?

Absolutely . .

Cheers

 

[mvh]

There is really no reason whatsoever to run a 160º thermostat. Only extremely low performance engines with maximally sized radiators and fans in cool climates will be capable of running at a stable 160º, and if they did, it would be inefficient as that is too cool for efficient combustion (not to mention the heater would blow lukewarm). In any other situation, the thermostat opens at 160 and the temp goes to whatever it goes to based on the conditions... 180, 190, 200. So there is no point in using a 160º thermostat — it is the same as no thermostat at all, but with more restriction.

Just go with the 180.

 

[mvh]

Remember that 100% water boils at 100/212. If youre running a 50/50 water/coolant mix that raises the boiling point beyond 100/212 significantly. You're fine.

But the coolant is under pressure, typically 14-16lbs. At that pressure, the boiling point of water is more like 230º. You can run all day at 212º with no problem if the system is holding pressure.

 

[4spdragtop]

Thanks, I forgot the wiggle room so to speak with sealed system and higher temps.

But the coolant is under pressure, typically 14-16lbs. At that pressure, the boiling point of water is more like 230º. You can run all day at 212º with no problem if the system is holding pressure.

 

[4spdragtop]

Googled

But the coolant is under pressure, typically 14-16lbs. At that pressure, the boiling point of water is more like 230º. You can run all day at 212º with no problem if the system is holding pressure.

 

[67Dart273]

Remember that 100% water boils at 100/212. If youre running a 50/50 water/coolant mix that raises the boiling point beyond 100/212 significantly. You're fine.

Except it doesn't under pressure. That's why we use pressure caps.

Blog - How Radiator Cap Pressure Affects Cooling

flex-a-lite.com

"Straight water at atmospheric pressure boils at 212 degrees Fahrenheit. A mix of 50/50 coolant and water boils at around 220 degrees. That same mix at 16 pounds per square inch (psi) of pressure boils at approximately 250 degrees. And the boiling point increases 2-3 degrees for each additional psi of pressure in the system. So the over-simplified answer to the tech quiz is that, yes, a higher pressure radiator cap can help prevent overheating."

 

[Demonic]

The factory went to 195 thermostats across the board by 1970. Get a thermostat with an 1 7/16" diameter opening section like an EMP Stewart from Summit.

 

[Professor Fate]

The factory went to 195 thermostats across the board by 1970. Get a thermostat with an 1 7/16" diameter opening section like an EMP Stewart from Summit.

Excellent point. I forgot about the factory bumping up the temp. in '70.
So to the OP, if the factory felt the t-stat didn't need to open until 195* and then allow coolant circulation, 200* is well within factory operating tolerances.