Best high flow thermostat for a 1970 440?

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Last year, Car had a Motorad 195F, then I tried a Gates 195F thermostat. Over 85F, car was running at 210F (225F in traffic), so I put a 180F Summit thermostat in. Over 85F, it runs at 200. (210F in long traffic). I kind of understand why the drop, since thermos start to open at that rated temp and are not fully open until 5 or 10 degrees hotter, plus rated opening temp is not accurate, but whatever, I was happy.

My problem is now when weather gets under 60F, it runs at 160F. It warms up to 160F within 5 minutes so I think thermostat is working properly.... or is it stuck open?

Mr Gasket has a high flow 180F thermo, but gets bad ratings for sticking closed. I could not find any RobertShaw and Stewart rated at 180F for a 440. So is there a real "High Flow" 180F thermostat for the 1970 440? Some say High Flow, but measurement of opening is still 1.125" just like standard, so how is it high flow?

PS - I guess I can try the 195F RobertShaw High Flow 1 7/16" opening since they say 195F rated opening temp very accurate and it fully opens at 195F, but after trying a Summit and then a Gates standard 195F thermostats, afraid car will run 225F.

Thanks for any help!
 

WOT440

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Back in the day, people in cooler climates would change out their thermostat depending on the season. 190F in the winter then back to 165F for the summer.
 

CBODY67

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The old "Robert Shaw" brand of thermostats was used OEM by Chrysler for many years. Then the company got sold to another entity, back then, and Chrysler went to the normal style of thermostat, with no real issues that I recall. So, the "normal" style should work good enough, by observation, as that style is OEM with GM and such, "forever". Over receent history, the "Robert Shaw style" thermostat has resurfaced from a few sources, from Mr. Gasket first, as I recall, then a few other "performance" vendors, even OReilly Auto Supply.

"High flow" can NOT always be your friend. Having the coolant flow too fast will NOT let it absorb enough heat for transfer to the radiator . . . as there is a window of opportunity for such flows to work best. In my case, I goT a reman pump for my Camaro 350 that was an aftermarket casting, with smoother inner casting surfaces, even a bit larger, and all the time it was on the car, the needle on the temp gauge ran 1 needle-width higher than it did with the OEM-casting pump that had been on there and the OEM-casting pump that replaced it. Just my experiences.

If the car is running a bit warmer in traffic at higher ambient temps, two things. The lower parts of the radiator can be getting clogged (although things look fine through the filler neck) AND similar with the lower sections of the coolant passages is the rear of the block, where everything settles out. So two things for consideration.

The OEM t/stat was a 195 degree F thermostat, although by 1972, Chrysler had gone to a 185 degree F thermostat OEM, although this was a short-lived item. So, pick your choice of temps, either 180 degrees F or 195 degrees F, although most would probably choose the 180 item. Do determine of the fan clutch is doing all that it can, too, as to the higher temps in traffic.

For additional diagnostics, you might get a infra-red heat gun thermostat to check coolant system temps. Top, middle, bottom, and hose temps at the radiator. Cyl block temps, front to back, top to bottom, rh to lh to look for patterns, too. Plus at the thermostat housing.

Things might not really be as dire as they might seem. KEY thing in the coming months is that the heater works well.

Just some thoughts,
CBODY67
 

1970FuryConv

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Last year, Car had a Motorad 195F, then I tried a Gates 195F thermostat. Over 85F, car was running at 210F (225F in traffic), so I put a 180F Summit thermostat in. Over 85F, it runs at 200. (210F in long traffic). I kind of understand why the drop, since thermos start to open at that rated temp and are not fully open until 5 or 10 degrees hotter, plus rated opening temp is not accurate, but whatever, I was happy.

My problem is now when weather gets under 60F, it runs at 160F. It warms up to 160F within 5 minutes so I think thermostat is working properly.... or is it stuck open?
I would stay with the current thermostat unless it's causing your engine to run rich and fouling spark plugs.
 

413

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Sounds like the T stat is working properly.

Cover part of the radiator with cardboard in cooler weather so it will run a bit warmer. Works at my house.
 
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