Hi

First, I'm sorry, my english is not very good.

My super six has cooling problems. In summertime when the air temperature is high, the engine is running after 20 mile run very hot. It's not boiling if I keep speed under 55 mph. And now wintertime the engine wont get the temperature. It's running cold all the time.

I have changed thermostat, but it didn't help.

Do a search on "overheating". Julie Roth had a lot of problems with overheating and there are lots of suggestions in that thread.

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Chuck Rivers, Webmaster

I already read everything, but why the engine is not getting the normal temperature at cold weather.

If there is sufficient coolant, and the thermostat is the correct value and functioning properly, then I see no reason for it to run too cold.
The thermostat's job is to withold circulation until the specified operating temp is reached.

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'66 Cuda 225/4spd
'66 Dart GT convertible 225/auto
'64 Dart GT 340/4spd

Is the heater core by-passed? That will keep the engine from warming-up.

If it is not that, then the thermostat is stuck open.
Look inside the radiator when you first start the car, cold. If the coolent is moving in the radiator tank, the thremostat is stuck open.
DD

If the thermostat is reversed, it may stick too. It should have a marking on it that says "rad" or "head".

Lou

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Home of Slant6-powered fun machines since 1988

Heater core is not by-passed.Thermostat is not reversed and it's closed when I start motor, so it's not stuck open. Maybe I'll have to clean the whole cooling system.

What is the correct radiator gap pressure. I have 50 kpa (7 PSI)

The factory cars, I believe, had a 13-15 psi cap. I run these higher pressure caps and have never had a cooling problem.

Lou

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Home of Slant6-powered fun machines since 1988