Overheating issues on a rebuilt 360

'63GT said
Have the cam number? Make?

'63GT said
Eliminate the bypass (pump to manifold) during break-in. This ensures ALL of the water makes it to the radiator, and you will be able to complete break-in without interruption.
I run mine that way all of the time.
BTW, Big blocks don't have them.

You mean the thermostat? Cause if that’s the case I removed it and still gets over 180