Most likely everyone knew this but me. I have a Cleveland motor in my 56 Ford F-100 and in the process of tuning and fixing things, I installed a new thermostat. No big deal, but the thing continued to run hot with the AC unit on and an outside ambient temp. of 109 degrees ( I live in the desert). Now, I know what your going to say...outside air 109 degrees....no wonder.
Actually, the parts house sold me a themostat that will work in a Windsor or a Cleveland, they're inter changeable.
Wrong! The Cleveland thermostat has a "hood" on the bottom that closes off the by-pass hole in the front housing. The Cleveland front casting has a top mounted ( like an Oldsmobile) thermostat location, the Windsor goes into the manifold.
If you don't use the correct thermostat in the Cleveland the water stays in the motor and doesn't flow to the radiator properly.
Problem solved .... FYI
Bill...the cobra is an FE..no problem there.