Apple pie with ice cream!!!!!Now I'm hungry again!!
Yes you do need a thermostat.With a weak cooling system I have cut the center out of an old thermostat to make a restrictor.This will keep the water in the radiator longer for better cooling.

Wanted Good Woman:
Must be able to cook , clean , sew , tune engines and polish trucks. Must have old Stovebolt and garage. Please send picture of old Stovebolt and garage.