ClassicCar

I have recently completed the engine in my 1953 F-100. When i run the engine, the temperature gauge just keeps rising and rising. Without the thermostats, the engine runs fine and the thermostat never goes past the one quarter mark away from the cold. With the original thermostats (180 degree), it overheated. I tried 160 degree thermostat with the same result. All the components of the cooling system are new (Water pumps, radiator, piping, thermostats, temperature sending units). I don't understand what could be causing this. If someone has any insight, i would appreciate it.