[toolboxchev]

Couple of things, first verify actual temp by using an infared laser thermometer.

Second, every auto parts junk warehouse call sell you a temp sending unit for the incorrect application. If you use a modern unit for a later year which, will fit, will work, yet give you incorrect readings. If its sending the wrong electronic information to the gauge you will get screwy readings.

Thermostats specs vary greatly by manufacturer, I am using a premium Stant 180 degree Stainless unit. Their regular stuff is junk, stay away from the fail safe design. It works and then clicks and stays open not allowing the coolant to pick up the heat and transfer it out to the radiator.

Using the correct radiator cap for your setup matter a ton also. Pressurized at 16lb cap with reservoir is what I like. I can see a 10-15 degree temp drop when running the heater.

On a final note, the spark advance at idle, for a street machine is preferred for my purposes. Try an adjustable vac advance from Pertronix and dial it to your engines needs with a timing light and vac guage. You would also have to take into consideration what type of cam you had installed. Some cam profiles do not produce much vac at idle.

When you have the wrong combination of these things the entire system will act like a heat soak. Another words when its starts to get warm, it will get hot due in part to incorrect A/F ratios, timing, lack of intial advance and so forth. Tuning skills really help here.

Todays Ethanol fuels like more intial advance, due to chemistry. And Warmer temps to burn completely.

All my fans are stock, no clutches, no electric fans, stock, stock, stock.