The absolute value of the EGT readings is not important because the thermocouple is averaging out heating from the hot gasses for one third of the time when the exhaust valve is open, and cooling by radiation to exhaust pipe and exhaust port walls as well as cooling down the shaft of the thermocouple sheath to the outside world where the cooling air blast is blowing by.  What is needed is for locations and depths of EGT probes to be as alike with one another as possible.  Whatever the others have for installation should be mimicked.

 

See latest Savvy Aviator newsletter for more on EGT probes and measurements.   Good article there by Mike Busch.

 

Fred Moreno