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PMag tach hookup for retrofits

T

Tom @ N269CP

Well Known Member
Simple question:
I will shortly be replacing only the right Slick mag on my O-360-A1A with a P-114 PMag (v.40). I will then have one Slick IC mag and one PMag. The p-leads from both existing Slick mags go to the respective L&R terminals on a single keyed ignition switch, with wires from each L&R terminal routed to a Horizon P-1000 tach. The input signal voltage for the tach is 100-1000 vac. Will the p-lead signal from the PMag support my Horizon P-1000 tach? Or is some kind of signal conditioner required? I could not find the voltage/freq characteristics for the PMag p-lead in the installation manual to do the comparison myself.

Another question:
I see that some users install a flow restrictor (snubber) in the MAP line to the PMag. EMag also recommends this be installed. Can anyone recommend what make/size restrictor and how best to do this? Is there an Aircraft Spruce (or other) part number for the restrictor?

I'm not the original builder but wish to help guide the workshop doing these mods.
 
Last edited:
If you have an AN fitting in your MAP line, you can drill a small hole in an AN 4 rivet and put it in that fitting.

I just happen to have a spare PM your address and I'll drop it in tomorrow's mail.
 
Tom @ N269CP said:
Simple question:
I will shortly be replacing only the right Slick mag on my O-360-A1A with a P-114 PMag (v.40). I will then have one Slick IC mag and one PMag. The p-leads from both existing Slick mags go to the respective L&R terminals on a single keyed ignition switch, with wires from each L&R terminal routed to a Horizon P-1000 tach. The input signal voltage for the tach is 100-1000 vac. Will the p-lead signal from the PMag support my Horizon P-1000 tach? Or is some kind of signal conditioner required? I could not find the voltage/freq characteristics for the PMag p-lead in the installation manual to do the comparison myself.

Another question:
I see that some users install a flow restrictor (snubber) in the MAP line to the PMag. EMag also recommends this be installed. Can anyone recommend what make/size restrictor and how best to do this? Is there an Aircraft Spruce (or other) part number for the restrictor?

I'm not the original builder but wish to help guide the workshop doing these mods.
Click to expand...

Well, I've figured out what needs to be done about my existing tach for my hybrid magneto/PMag installation. So am posting this up for those who may follow in my footsteps.

Neither EMag nor Horizon were able to come up with a solution for reusing my existing Horizon P-1000 tach.

The solution is to replace the Horizon tach with a Flight Data Systems T-30 tach. The T-30 can concurrently receive two speed signals, one from a magneto p-lead and one from the PMag 12v tach output. This has been confirmed by the helpful folks at Flight Data Systems.
 
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