Topic: Thermostats and Temperatures


JayRM    -- 11-14-2021 @ 4:18 PM
  On a fairly stock flathead V8 (Navarro heads), using an infrared temperature reader, all temps at pertinent locations are just where they should be after a lengthy run. Not surprisingly ( I suppose) the stock temp gauge, after running awhile, reads toward the high end. After all, in absolute terms 160-200 degrees is hot. But, those are normal and expected temps-are they not?

Is anyone replacing the thermostats with others that keep the temps down or not? It's my understanding that these engines do "best" at the temps mentioned above.

Thoughts and suggestions are much appreciated.

Thank you.


carcrazy    -- 11-14-2021 @ 4:54 PM
  One rule of thumb for Flatheads is that they will run at a coolant temperature of about 100 degrees F warmer than the outside ambient temperature. I like to run 160 degree thermostats in these engines. Temperatures of 180 to 200 degrees can be expected to be normal if the ambient temperatures are over 80F. Be sure your cooling system is clean and your radiator is as good as it can be.

The Flathead is probably most efficient at temperatures of about 180F. When you are accelerating or climbing hills the temperature of the coolant will increase.

The thermostats only control the temperature of the coolant until the engine gets up to operating temperature. Once at operating temperature the engine will run where it wants to.

You might want to install a good mechanical temperature gauge under the dash to keep an eye on the engine's temperature under load while going down the highway. Stewart Warner is one provider of good mechanical gauges.

This message was edited by carcrazy on 11-14-21 @ 4:56 PM


JayRM    -- 11-14-2021 @ 6:09 PM
  Thank you for those thoughts and pointers.

I think I will install a temp gauge to check against the OEM gauge.

How do I go about determining which thermostats are installed presently?

Regards,

Jay


carcrazy    -- 11-14-2021 @ 8:28 PM
  Take the old thermostats out of the engine. Look at the thermostats to see if they are marked. Place them in a pot or can of tap water with a candy or similar type of thermometer and heat the pan on a stove as you watch the thermostats and the thermometer to determine when the 'stats begin to open. Be sure to keep the tip of the thermometer above the bottom of the pan so you will be measuring the temperature of the water rather than the temperature of the bottom of the pan.

This message was edited by carcrazy on 11-14-21 @ 8:33 PM


JayRM    -- 11-15-2021 @ 6:10 AM
  Thank you for that pointer on determining which thermostats are installed in the '40 Ford. I will soon be boiling up some thermostats. I best warn the household not to sample.


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