Plug Cans Shortcomings

[flyguy]

Think I have the noise problem on the remaining noisy ignition system nailed down to the screw-in can lids. The lids are so loose that they cannot be making good electrical contact. I haven't been able to figure any way to get good electrical contact and still be able to secure them from coming out.

Anyone have a way (simple or not) to get good ground continuity on the screw-in lids?
Darryl

[VictorBravo]

Re: Plug Cans Shortcomings

Electrolytic Grease? If you can keep the grease from melting and running all over, it should work. Otherwise you need a ground strap between the lid and the can.

[flyguy]

Re: Plug Cans Shortcomings

Thanks Bill, thought of the grease, but the strap is really a good brain teaser. New direction, and might work.
I will throw something out and perhaps someone can suggest the best way to do it.

If there was a offset in the inside threads or a bump that the lids would bottom against just as were at the correct depth for securing with the cotter pins, that would make good electical contact to the shell.

How to make the offset/ bump/projection/whatever that the lids would run into as they are screwed down, that is what I am puzzling with just now.

Any suggestions?

Mine-- 1: I have a small V chisel to put maybe 4 gouges at the correct spot in the threads. 2: maybe 4 welded bumps inside at the correct places.

Don't think the grease idea would provide low enough resistance, has to be about the same as a soldered joint, very low Ohms.

Darryl

[Ragwing nut]

Re: Plug Cans Shortcomings

I drill a small hole in the side after the cap is tight and install a cotter pin through the slot.

[VictorBravo]

Re: Plug Cans Shortcomings

I drill a small hole in the side after the cap is tight and install a cotter pin through the slot.

JACKPOT! Mike got it exactly right !

Be careful, mine did not work reliably because the current was arcing from the spring to the cap or the can and not through the plug.

[Hank Jarrett]

Re: Plug Cans Shortcomings

The cans I've got have a small drill hole through the top and out the side (kind of a 45 degree hole) that takes a piece of safety wire. Serves two purposes, keeps the cap from turning (in and shorting against the top of the plug or out where it could fall off), and I guess I didn't know it, but the safety wire would provide a pretty good electrical ground.
Hank

[flyguy]

Re: Plug Cans Shortcomings

Well, I have suceeded in embarassing myself. I really hadn't actually checked the continuity between the "lid" and the can body. Since the threads were rather loose I just assumed it was poor. You know what assumed will get you. Chuckle.

So I turned loose my trusty Fluke Ohmmeter on it this AM. Measured 0.2 Ohms more or less with the cotter pins pulled up tight. So much for that being the problem.

Think I have a handle on it though. Last item. The plugs are C-26's, which I believe have no resistor in them. That is a sure way to make a sharper rise on the pulse with more ring during discharge. Anyone know if C-26's have internal resistors. I didn't have time to pull a plug this AM and if I ever knew, I have forgotten.

My latest is that the noise generated by undamped plugs may be so much that it just overwhelms the shielding.

That pretty much puts me back at cowling bumps and standard shielded resistive plugs.

One last question. Anyone know anything about or which manufacturer it is that uses the spiral wound center conductor in their ignition harness wiring?

Darryl

[Hank Jarrett]

Re: Plug Cans Shortcomings

Probably been said many times before but check the P leads to the mags again, ESPECIALLY where the wires go to the Mag switch. Maybe try unhooking the leads from the mag and running a second set of shielded wires out the bottom of the cowl to a well shielded switch. Do a ground run and see if the noise goes away with the Mag switch and leads completly out of the picture.
It just seems like most of the time the noise seems to end up coming from the wires from the mags to the panel or the Mag switch itself.
Hank

[flyguy]

Re: Plug Cans Shortcomings

I did a check with the "P" leads disconnected from the mags before and it did not cure the problem. That was before I reworked the shield on the one mag that is quiet now. It would have hidden the quiet one then as I did it with both of them off. I will be sure to check it one more time on the noisy mag, along with anything else that I do.
DC

[Ragwing nut]

Re: Plug Cans Shortcomings

You can change over to the M41N plugs and Skytronics are my preferred harness maker.

[flyguy]

Re: Plug Cans Shortcomings

I have a new set of 41's, but they are straight thru plugs (no resistors) as far as I know. So no help there.

It is a problem using them with the cans I have as the 41's wedge down in the counterbore at the bottom and it is very difficult to get the plugs and cans off. That is the hex hides in the bore and there is no surface exposed to grab with a socket. Have to solve that problem someday when I can't find good condition C-26's anywhere.

This thing has just become a personal challenge as I now know that the Eisemann's can be made quiet and there is nothing basic with the magneto itself that prevents it. Can't resist a challenge. It will be really nice when I go into controlled airports to hear the guys loud and clear.

Appreciate the suggestions from eveyone.

Darryl