Magnetron Ignition Modules

[Bryan Cotton]

Jim,
You can definitely change the magnetron without pulling the engine. You need to sneak a wrench onto the nut, either past the magnetron or from the side. Getting the nut started can be done with forceps or taping the nut to the wrench. Check out the Sonex video and manual.

[Bryan Cotton]

Also, a regular feeler gauge may not work great. Sonex supplies a long 0.010" thick strip that goes well past the ends of all the magnet stuff. When you put the magnetron on, the magnet should not be underneath it so you can easily push it away from the flywheel. Snug down the screws. The long strip sticks to the magnet, and you rotate the magnet under the magnetron. Loosen the screws and the magnetic attraction will pull everything together - magnet, shim, and magnetron. Tighten the screws for keeps and turn the engine so you can grab the strip.

[funflyingguy]

hi bryan,

much appreciated. the long feeler gauge and replacement magnetron has been ordered. will update this post soon.

jim

[funflyingguy]

bryan,

as my ordered parts begin to arrive, have another question..... do you remember what size those 2 nuts are on the back of the plate holding the top magnetron? ( i read somewhere here about a 7/32" nut. that seems rather odd)

[Bryan Cotton]

Depends on which nuts you use. I think they are #6, and I use MS21045 which need an 11/32" wrench. 7/32" could be right for an MS21042. They could be #8 screws as well.

[Bryan Cotton]

The manual shows MS21042 nuts and calls out a 7/32" wrench.

[funflyingguy]

thanks bryan. i obtained a manual and see that now.
jim

[funflyingguy]

so.... yesterday, i bit the bullet and replaced the top magnetron on my aerovee engine. it it working normally again, including the mag check. all the suggestions here helped alot. still, it seems that these should be a bit easier to service. first, 7/32" is an odd size requiring a really tiny, uncommon wrench to remove. i thought about a larger bolt, a 1/4" nut and boring the accessory plate out to that size, but left that for the next time. also, the spark plug leads are so much in the way of the left side nut on the magnetron, that i ended up tying a small weight to them to pull them over to the right side of the engine for more opening. it was barely enough. still, a good experience to have done it. i never got to do anything that involved on my piper cherokee!
so a question....... i realize the safety factor of have a magneto/magnetron setup. but does anyone know of a reasonable replacement (cost and maintenance) for the magnetron setup?
.... jim / funflyingguy

[Bryan Cotton]

does anyone know of a reasonable replacement (cost and maintenance) for the magnetron setup?
.... jim / funflyingguy

After 2 years, 270 hours, I think the magnetron setup is good. Regarding boring the holes up to 1/4", you would have to upsize the slots in the magnetron laminations. Seems a lot easier to buy a 7/32" wrench, and when you need a new magnetron just buy and use as-is.

[funflyingguy]

hey bryan...
actually, i did end up buying 2 7/32 wrenches. i used the 2nd to do the job. (the first broke, shorter and flimsier) but both are so short as to making holding onto them difficult. the bigger ones are progressively longer, making reaching into that tight and deep area that much easier.
i will likely use them as is the next time, although i hope thats a few years down the road.
by the way: i only had 30 hours on the aerovee since i bought it before the magnetron went bad. it was an original from 2012, maybe 2011, with 280 total hours on it.