EDM 740 RPM configure

[bergy]

Hi,
Just reinstalled my overhauled P-Mag. Works a treat except l can get 4000+ RPM now from the 0-235. The factory ignition was set to default 2 pulses instead of the one pulse from when l first purchased it. I have looked through the JPI pilot manual p61:-

Number of Cylinders
This affects only RPM capable EDMs. Set RPM SENSOR PULSES PER REVOLUTION = 4 or 6 depending on your engine. Exceptions:
• 4 cylinder engine with dual (all-in-one) magnetos set to 8. • 4 cylinder Lasar® ignition set to 8.
• 6 cylinder Lasar® ignition set to 12.

Given the p mag does either one or two pulses per rev perhaps someone knows the number l should try?
Any input would be most helpful rather than overheating the engine in the run up bay. BTW It’s my first post here after lurking for years. Sorry for the basic question.

Dave
VH-JZE

 

[blaplante]

On a 4 cylinder 4 cycle engine you'd have 4 ignition events in TWO revs. So 2 ignition events per crank rev.

One point of confusion is when the P-mag says pulses per "Rev" do they mean an engine rev? Or a MAG rev? Mags run at 1/2 speed to the crankshaft.

 

[bergy]

Good question. . Now that the p-mag is set for two revs instead of one….l think it’s a pulse from the mag per the mags internal revolution. So not knowing the gearing it could mean anything relative to the engine strokes?

I’m just back from the plane. The setting for the JPI is poorly documented but labelled ‘pulse’ when you get through all the screens on the EDM 740. I didn’t know it was there! It was set at 4 so tried 2 and if that didn’t work l would try 8. You can set from 1 to 99

8 works.

Many thanks for the input!
Dave