P-Mag and IFR

SHesse · #1 03-01-2011, 06:11 AM

If any of you fly IFR with P-Mags I have a question please:

Is the harness for auto plugs really reliable? I am about to swap from traditional magnetos to P-Mags which are electronically superior, no doubt! But flying IFR in heavy rain... Can somebody please calm my lurking doubt when I see the unshielded harness clicked on bare porcelain spark plug insulators, as opposed to metal capsule spark plug, susceptible to get dirty and lead electricity on its surface, at high voltage when wet.

Thanks, Stefan

woodmanrog · #2 03-01-2011, 06:21 AM

I have asked the same question and was led to this conclusion. I have heard of instances where a plug wire popped off of a spark plug in flight. Not an earth sattering occurance but I know that it will really get your attention when it happens. I too am going for p-mags but I am electing to stay with aircraft plugs and wiring. I know that is way more expensive but I like peace of mind.
Woodman

tommylewis · #3 03-01-2011, 09:54 AM

I have 800 hours on my RV7a with dual Pmags and have not had any issue with the auto plug or harness. We do fly IFR.

algrajek · #4 03-01-2011, 10:41 AM

Why not use aviation plugs. If you use fine wire you can go to a larger gap which makes the PMag mote efficient. I think the harnesses cost about the same
Al

Ironflight · #5 03-01-2011, 10:54 AM

When I spec'd out the new engine for the RV-3 with Mahlon, I decided to go with P-Mags, and expected it to have auto plugs. Heck, I've got a couple of boxes of BR8ES's left over from my Jet Ski days, and figured I'd be set for awhile. Mahlon said "oh, we deliver it with aviation fine wires, unless you ask for something different". I was perplexed about why I wouldn't want to go with plugs that were inexpensive to change, until he said "oh, the fine-wires should last until TBO!" OK, so I can have expensive plugs that last forever, or cheap ones that I have to change a bunch. With the expensive ones, I get an aviation, screw-on cap....I liked that option. As always, I went with Mahlon's reasoning and recommendation.

Smart man, that Mahlon....

allbee · #6 03-01-2011, 11:23 AM

interesting thought. I run auto plugs on top and bottom with ei on both. I suppose you could put plastic wire tie's on the boots to keep them on. I just might do that on my next oil change, yup, sounds like a good idea. My wires have not come off, 480hrs and counting. First flight in april 09

when I say put ties on, that's loop them around the end and pull them tight, makes a tighter fit. like putting a clamp on a hose.

Toobuilder · #7 03-01-2011, 11:33 AM

I've heard the stories of wires popping off, but in many years of building/racing hot rods, motorcycles, boats, airplanes, etc, I have yet to EVER see a spark plug wire come off on its own... Not a single time.

I'm sure it's possible, but what are the odds, really?

miyu1975 · #8 03-01-2011, 11:39 AM

interesting thoughts Paul..and Mahlon, I will have to rethink this as I was planning the auto plug route.

nucleus · #9 03-01-2011, 11:49 AM

I have flown quiet a bit in moderate rainfall never had any problem with the automotive style wires.

When I was in phase one I did have one boot that would feel a little loose after flying. I resolved it by changing the way it was routed and supported. It was not anywhere close to coming off and never misfired. I supposed we could make a harness that screwed onto the auto plugs if we wanted.

Hans

loopfuzz · #10 03-01-2011, 11:51 AM

I have a EI on the top 4 auto plugs. And fly in the wet pacific NW. Since I replace the auto plugs each annual (and inspect the plug wires too), I have not had any issues.