I just installed a Pmag on my plane which already has an Electroair. I was curious how the timing advance for the Pmag compared to the Electroair so I did a test last night at three points using the monitor program. Shift was set to zero so this is the Pmag A curve. I am not sure if the results are normal for a Pmag or if there is a problem? The Electroair will always have a lot of advance at low MAP regardless of the RPM.
1) Idle, RPM = 1040, MAP = 12"
Pmag Advance = 2 deg
Electroair Advance = 13 deg
Below ~16", the Electroair vacuum advance is maxed out
2) Runup, RPM = 1700, MAP = 17"
Pmag Advance = 6 deg
Electroair Advance = 12 deg
I did a mag check here and got no drop when shutting off the Pmag and a 70-80 drop in RPM when shutting off the Electroair. That is to be expected based on the timing differences.
3) Full Power, RPM = 2400, MAP = 28.5"
Pmag Advance = 3 deg
Electroair Advance = 1 deg
The Electroair vacuum advance is zero above 24" and it was installed to be at approximately base timing during takeoff
Does everything look right with the Pmag values? Does it intentionally not advance at idle? I have not flown with the Pmag yet and have no idea how they would compare at cruise at 8000 ft (high RPM and low MAP).