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Discussion Starter #1
After having my AC installed, my 351c started running a little warmer on hot days, 235F. So I ignored what I read here and "assumed" the PO had the correct thermostat and i ordered an ACP Maxcool 2 row, much better but still would climb on hot days 220-225f. So I decided to check the themostat and bingo! A t-stat with the hat but not a correct Robert Shaw type. I ordered a Robert Shaw 180 from West Coast Classic cougar and bam 190-200f on hot days.
Moral of the story, pay attention to the valuable information and recommendations you see here, I may not have needed to remove my seemingly new brass 3 core radiator. Keep up the great info guys.
20200420_091108.jpeg
 

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In your pic, which is which?
Thanks.
 

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I've read a lot of overheating threads on here and never really caught this. What's the benefit? I'm pretty sure my thermostat is just a regular old 195.
 

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Cool😂 thanks
 

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I’ve used both with no issues. Issues for me pertained to timing and carb tuning.
 

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Robertshaw uses better quality materials with a more consistent opening type with greater flow and a de-gas port. I recommended and sold them over all other types and brands 25 years ago and I still would.
 

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Discussion Starter #8
Greater flow seams to be the key for the 351c. Looking at the 2 types you can see the difference and I have much better cooling in my cleveland.
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67 coupe, 69 Sportsroof, 86 hatchback
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Weird. I've not heard of anyone touting a Robert Shaw over a factory Ford Motorcraft before. But people using some other temperature rating than the usual 192F one comes up a lot. Not really going to beat that horse again but here is the top result of what a Google search for "optimal operating temperature for a gasoline engine"" returns:
"The engine operating temperature range for most cars is between 195 to 220 degrees Fahrenheit. The optimum temperature is around 212 degrees Fahrenheit. "
This does not apply to racing like in NASCAR where they are currently finding optimal performance running at 290F.

You know, just me, but I LIKE optimal performance.
 

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Discussion Starter #10
I've read a lot of overheating threads on here and never really caught this. What's the benefit? I'm pretty sure my thermostat is just a regular old 195.
From what I can tell this mainly pertains to 351c because of the cooling system set up.
 

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"The engine operating temperature range for most cars is between 195 to 220 degrees Fahrenheit. The optimum temperature is around 212 degrees Fahrenheit. "
This does not apply to racing like in NASCAR where they are currently finding optimal performance running at 290F.

You know, just me, but I LIKE optimal performance.
I run a 195 degree thermostat but I think you have to define optimal here. Why do engines make more power on the dyno with cooler coolant temps? Does optimal not mean the most power? Does it simply mean the cleanest burn for emissions purposes? And in that case does fuel matter? 110 octane leaded gasoline vs. 91 octane E15? Are there other variables? Does a 195 degree engine like a different air fuel ratio or timing curve than a 180 degree engine?

I can tell when my car is at 220. It doesn't seem to run as well as closer to 200. Why would that be? Seems like either one would be fine.
 

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"Does a 195 degree engine like a different air fuel ratio or timing curve than a 180 degree engine? " Absolutely!

It's called "tuning". Put a wideband O2 gauge on that sucker and look at lean and rich. It's a lot easier to figure out with early OBDII cars where you can read the long and short term fuel trim effects of temperatures. Versus the later systems where the computer can directly control the cooling system also. On those it's less obvious what's going on. People have been tricking fuel injected engines into running a beat leaner be altering what the computer sees the engine temperature to be.

Emissions? A modern 5.0 can make 412 horsepower stock operating at 215 degrees F, straight off the dealer's lot. The best any other stock Ford 302 did was the Boss at around 290. Non-Boss 302/5.0's, what, the somewhat overrated Hi-po 289's at 271? It's not all about emissions.


I'm not making this stuff up, just relaying information. There's plenty more out there, as I've already mentioned in one simple Google search.
 
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I think what GypsyR is trying to say is that 220F is safe. Assuming you have the proper coolant mix and a good radiator cap.
The reason you see a performance drop at higher temps is because of all the hot air under the hood.

I’d argue that a nascar engine running at 280F is not at peak HP. But it’s a trade off.
The grill opening for the radiator is very small for the sake of improved aerodynamics. So, less air through the radiator = hotter engine but is faster overall.
And their air intakes are designed to only draw in cooler outside air.
They are probably also using “waterless” coolant which has a much higher boiling point.
 

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Also, a 2020 mustang GT comes from the factory with a “cold air” intake. It’s not pulling air through a open element filter on top of the engine.
And it has sensors for:
Intake air temperature,
Mass air flow (density),
Manifold pressure,
Meaning it can instantly adjust fuel metering according to changing atmospheric conditions.
 

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Again, why do engines on a dyno consistently make more power at lower coolant temps?

I'd love to hear theories about that one. I'm not trying to be argumentative, I already have the correct thermostat in my car because I believed what I read here. I just want it all to add up.

Emissions? A modern 5.0 can make 412 horsepower stock operating at 215 degrees F, straight off the dealer's lot. The best any other stock Ford 302 did was the Boss at around 290. Non-Boss 302/5.0's, what, the somewhat overrated Hi-po 289's at 271? It's not all about emissions.
The new 5.0 that makes 412hp has a lot more going on than precision control over, and higher, coolant temps. DOHC 32 valve, 12:1 compression, independent variable cam timing, dual fuel injection system, variable ignition timing- you name it! I get what you're saying. The engine management progression has favored increasing coolant temps over time. If cooler was better, they would have figured that out. But I still think emissions is a big part of that.

The reason you see a performance drop at higher temps is because of all the hot air under the hood.
Maybe. But on an episode of Engine Masters they did all sorts of drag racer tricks like icing the intake and found that the Intake Air Temperature was so cold due to the intercooling effect of carburetor fuel atomization that anything else they did was basically irrelevant. Direct injection, and even fuel injection that is in the intake runner or cylinder head intake port, will not get this benefit because there simply is not enough time for the heat absorption to occur. A Cold Air Intake on a muli-point or direct injection fuel injected car makes much more sense.
 

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Lord, GOOGLE people, GOOGLE. You can use it to learn stuff instead of just posting blue sky conjecture. I thought I might regret trying use endurance racing as an interesting example. Like all race cars on paved tracks, they use WATER as a coolant. And yes, I know how modern engines differ from antique ones. I thought I gave a clue when I mentioned early versus late OBDII systems.
Cold air intakes? Pretty much every passenger vehicle destined for street use has had a "cold air intake" from the factory since the 1980's and many many more before that. Most of the 1970's stuff had them too. Yay, "Halo night" , got to go!
 

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That seems a little bit... terse? Has anyone posted anything here to show a total lack of their own research or knowledge? If you don't want to have the discussion, or the topic is too sensitive for you to reply back then... don't? I mean I asked a specific question. I don't want to Google why engines on the dyno make more power at cooler coolant temps. I can practically predict the answer which will be along the lines of "COOLER IS BETTER." I want to hear your theory. It's a discussion. I ask you questions because I respect your input. Not because I don't.
 

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My 68 with a 331 AOD, 325 gears has been running at 180 for many, many, many miles. The car starts and runs perfectly and gets 22-24 mpg on the flat and never ever overheats with air on in sweltering ambient temps.
Years ago I once asked if I would benefit from using. 195 t stat and the general consensus was leave well enough alone.
 

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Ok. I googled it.


I was wrong.
They are using straight water. And at much higher pressures than your typical 16 psi radiator cap.

It is a trade off.
They are giving up some HP by running at such a high temperature.
They are also giving up longevity of engine parts.

And while we’re nit picking, nascar is not endurance racing :p
 
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