• Welcome aboard HomebuiltAirplanes.com, your destination for connecting with a thriving community of more than 10,000 active members, all passionate about home-built aviation. Dive into our comprehensive repository of knowledge, exchange technical insights, arrange get-togethers, and trade aircrafts/parts with like-minded enthusiasts. Unearth a wide-ranging collection of general and kit plane aviation subjects, enriched with engaging imagery, in-depth technical manuals, and rare archives.

    For a nominal fee of $99.99/year or $12.99/month, you can immerse yourself in this dynamic community and unparalleled treasure-trove of aviation knowledge.

    Embark on your journey now!

    Click Here to Become a Premium Member and Experience Homebuilt Airplanes to the Fullest!

Ignition help needed

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

bifft

Well-Known Member
Joined
Apr 17, 2011
Messages
429
Location
Utah
So, I've documented a little of what I'm now calling The Neverending Condition Inspection over on another thread, but now I'm stuck. I sent in my magneto for a mandatory service bulletin, they sent me back a rebuilt one. When I install the rebuilt one on the plane, it works just the same as if that magneto isn't there at all.

I run one Slick magneto and one P-mag on a O-360. I start on the P-mag (the magneto is a non-impulse model) and that works normally. I go up to 1800 RPM, then switch the magneto off. No RPM change. Switch off the P-mag and the engine stops. If I turn it back on again before the engine completely comes to a stop it runs again, with a big "bang" (presumably unburned fuel in the exhaust).

Before I installed the mag, I checked the harness with a ohmmeter, all the lines tested out 0 ohms,. Checked that the harness is going to the right plug, the cylinder lines up with the number printed on the nut. Checked the timing again, the "buzz box" switches on right as it passes the 25 degree mark on the flywheel. I checked a continuity tester against my switch, it is grounded when the magneto is "off" and open when "On". The continuity tester does show a connection between the p-lead and the case, but from what I read this is normal.

I took the magneto back off, put it on the bench with the plugs installed and the outside wired to the ground plug. Rigged up a little block to spin it with my drill and all four plugs spark well. Not as big of a spark as I got out of the P-mag back when I tested that, but clearly sparking. I can even get it to spark most of the time just turning the gear by hand.

Is there anything else I can do other than just put it on the engine again? I guess I should gap the plugs again, but I just did that as part of The Neverending Condition Inspection.
 

Latest posts

Back
Top