That is an indicator that the REAL timing is NOT right. Lower
EGTS are the result of advanced timing. This is NOT good. If the
timing is correct the EGTs will NOT be lower. PERIOD. This is one
example of when lower temps are NOT good.
We have tested magnetos and
electronic devices and find that the actual spark event does not coincide.
This can be VERY bad.'
Would not the lower EGTs with electronic ignition
be caused by more complete combustion before the exhaust valve opens to let
still-burning gases flow over the probe? My totally amateur understanding is
that electronic ignition fires earlier before top dead center at cruise rpms
than does a magneto, it fires for a longer period of time, and with higher
voltage allowing a larger plug gap, all seemingly contributors to more complete
consumption of the fuel/air charge.
I'm asking in order to learn--I don't pretend to
know. Wendell Durr