Overheating during cam break in

a box fan helps, cuz breaking in a cam is NOT idling, and an initial fire up can have - the cooling system not full - the timing not perfect - the jetting not perfect etc. you want an assistant to check the timing at 2500 rpm, and to add coolant. and for initial fire up you want a hole in the therm. or no therm. and if a therm. is used always test it for opening in a pot of boiling water for opening. I have an old thin fiberglass "flex" fan that does not flex, a small lower pulley, no shroud-(shrouds add aerodynamic drag) and she is very slow (like 20 minutes) to get to 180*