When filling with water temporally remove the temp sender or the plug you have in its place. Make sure you fill the radiator until water comes out of the head before replugging. this bleeds all the air out.
I also question whether there is enough air flow through the radiator.
Retarded timing can make an engine run hot.
Thermostat removal causing overheating has been debunked many times. I never install a thermostat during break-in.


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