Eiseman Magnetos

[whake]

Can eiseman Mags. be converted to shielded wires to eliminate radio noise

[Dick Smith]

Re: Eiseman Magnetos

Walter, I had my Eisemann mags rebuilt and new shielded leads made up by this outfit. Been very satisfied.
Arn-Air in Bayard, Iowa Phone 712-651-2255

[whake]

Re: Eiseman Magnetos

Do you know your mag model number? did you have to change the spark plugs or add bumps on the cowling to clear the plug connectors? Thanks for the info.

[dewhitaker]

Re: Eiseman Magnetos

I just this spring converted over to shielded ignition. You do not have to use cowl bumps if you so desire. I purchased four shielding cups from Fresno and am using the good old C-26 plugs on the top. The trick with the shielding cups is you have to change the thread on it to accept the new harness, which has a 5/8 - 24 thread on it. The spring on the harness then fits nicely against the side of the plug. Works great!

The bottom set of plugs are the UREM40E. No problem there.

I took step by step photos of the process and will attempt to post some pictures later. I am at work now and will try to do it later today when I get home.

[whake]

Re: Eiseman Magnetos

I appreciate your help and looking forward to seeing the pictures

[VictorBravo]

Re: Eiseman Magnetos

What do y ou have to do with the threads??

[dewhitaker]

Re: Eiseman Magnetos

Hi Bill. The threads on the shielding cups from Fresno are too large, you cannot attach the harness to them. So they need to be cut down to the proper 5/8 - 24 size. To do this we took a 3/4 inch hole saw and ran a 5/8 inch drill bit into it to knock the inside teeth off the hole saw. Then we put the pilot bit back into the hole saw. The pilot bit was then covered with a piece of tubing. Now we have a tool that can be used to remove the oversized threads. Place the modified hole saw into a drillpress, place the cup into a vice and lower the tube covered pilot bit into the threaded connection. After ensuring everything is square, tighten vice and turn on drill press. Carefully lower your holesaw, and you will be cutting off the oversized threads. Use your favorite cutting oil for this, and work slowly. When done, you will have the correct diameter of 5/8 inch. Now take your 5/8 - 24 thread die and chase the new threads on. You will now be able to attach a shielded harness to the cups.

If I was able to fumble my way through getting these pictures posted, there should be pictures showing what I just described.

[dewhitaker]

Re: Eiseman Magnetos

Just some further thoughts on the project. We considered using the shorter UREM37BY plug for the two rear positions. But Dad just wasn't comfortable with the tight radius it would have placed on the wiring harness. So we did all four top plugs. As you can see from the completed views, there is not much room to spare. But it does fit under the cowling, without adding cowl bumps. You will note the safety wired cap. Just to prevent any accidental arcing inside the cup, Dad glued a piece of rubber to the bottom of the cap before we installed it.

While we were doing this, we brainstormed on how to make our own cups that would be easy for the tribe to make as an owner produced part. We have come up with something that I believe will work nicely. I want to test it on the Butterfly first, if all goes well I will post it later, and have a display set up at the Alliance Fly In, July 7-9.

Hope this helps. I really think it was worth the effort to retain the smooth look of the cowl.

[VictorBravo]

If you have to use a thread die to "chase" the new threads, what happens to the old threads? I mean, what is the exact thread size on the part as it comes from Fresno Airparts? If you take an AN-4 bolt, machine the diameter down to 3/16 and run an AN-3 (10-32) thread dise on it, you will not have a 10-32 bolt, you will have a big ugly mess.... no?

[whake]

Re: Eiseman Magnetos

great pictures great Idea, looks like a workable deal for me. thanks a lot
Walt

[dewhitaker]

Re: Eiseman Magnetos

Hi Bill, the size of the threads as recieved from Fresno is 11/16 - 24. By following the procedure I described, these threads will be completly removed, leaving you a 5/8 diameter size. Then it is easy to just rethread. They look great! Here is a link that will take you to further information.

http://www.bowersflybaby.com/tech/fenton.htm#radio_noise

[N96337]

Re: Eiseman Magnetos

What kind of approval did you get for this?
JH

[alwaysoar]

Re: Eiseman Magnetos

Here's another thought: it looks like a lot of trouble to convert the AM-4's to shilelded, so why not trade them in for Slicks. Dual impulse coupling, Unison pays a rebate and takes Eisemann's in trade, and they bolt right on. Net cost, about $1150.00 for the pair that includes harnesses and plugs. Hot or cold, my engine starts first or second pull every time.

Ed@BTV VT
TF 527

[flyguy]

Re: Eiseman Magnetos

You're talking about Fresno Air Parts out here? Had no Idea they had any kind of cups. I have a set that have the correct threads on the "as cast" part as they say in the hot rod business. The funny threads are obviously a weld-on modification to the original casting. Why would they screw up a standard part like that? Foreign usage? Wonder if anyone has the originals any longer? Someone said the one's I have were made for Aerocoupe's. (sp?)

Neat home-brew trick, making your own tool like that, ingenious. Nice photography too.
The main problem that I see is that the new R41 plugs won't work properly in those kinds of cups because the hex is shorter and goes down inside the relief and you can't seat a socket properly. (I have a set of 4) They don't make C26's anymore so sooner or later the supply is going to run out.
Anyway, I would think one would want to look around a bit for the originals with the correct treads as they obviously exist as witness the ones I have.
DC

[whake]

Re: Eiseman Magnetos

This is the direction or what I am going to try to do..Purchase a Skytronics shielded harness from Aircraft spruce, page 259. modified to fit the Eiseman model M-4 Mags. I will use RME40E plugs. Will purchase cowl bumps from Wag Aero. Hope to get by for about $500.. Does anyone have any experience with this approach?