Spark plug shield question

[dalepj]

See the attached photo. Does any one know where this type of spark plug shield can be found?

Thanks, Dale Jewett

[Hank Jarrett]

Re: Spark plug shield question

They are called Erocoupe (SP?) Cups and I understand El Reno use to have some. I have 4 for my plane but am having problems finding the old plugs and clips for the ignition leads.
There are two pieces of good news on the cups. First, you only need 4 (for the top plugs) and second, if you can't find them I have some info on how to make them I will try to scan and post.
If anyone has any of the old M-41 plugs (even if they are no good) let me know. My 41 has so little room above the plugs I'm not sure even the cups will fit when I make a new cowl.
Hank

[Carl E. Carson]

Re: Spark plug shield question

I just bought and installed them on my 40 BC 65. I bought them from Fresno Airparts. My info details are at the hangar but Google them and ask for the Ercoupe Cups.

Carl

[lfries]

Re: Spark plug shield question

Wiring harness couplings may not fit on the cups. I have a dye to correct
the thread problem that I'm willing to loan.

[Ragwing nut]

Re: Spark plug shield question

The thread size and pitch for the cups is the same as what it used on the magneto end of individual lead harnesses. I have a handful of nuts here. I also have had a handful of tops we had machined for the cast cups as well. What clips are you referring to? They did not use the old clips found on unshielded ignition wires, they used cigarette and spring against the ball.

[Hank Jarrett]

Re: Spark plug shield question

I'm "corn-fused". How would a cigarette and spring attach to the short plug? Which plug do you use with the cups and where do I get 4? How do I connect the leads to the plugs and Mag?
I guess i know a lot less about this than I thought! I'll post the page on making a cup tomorrow.
Hank

[Ragwing nut]

Re: Spark plug shield question

I'm "corn-fused". How would a cigarette and spring attach to the short plug? Which plug do you use with the cups and where do I get 4? How do I connect the leads to the plugs and Mag?
I guess i know a lot less about this than I thought! I'll post the page on making a cup tomorrow.
Hank

You can take a shielded harness and change the nuts on the spark plug end. then the lead will screw onto the cast cup. The spring on the lead that normally goes into the shielded plug is compressed against the plug end. Requires use of C26, C27, or M41N plug. Last time we had Skytronics custom make a harness with the correct nuts installed.

Now if you have the older style Breeze cups which are stamped brass and have a bail on the top to hold cover on, then a standard unshielded igintion wire set up is used. Last time we found a supply of clip ends was at NAPA. I have a bunch of leads that we have saved "just in case" we could not secure new parts anymore.

[Hank Jarrett]

Re: Spark plug shield question

Here is as copy of the instructions for making a cup if you can't get the commercial ones. I can't remember where I got it but it was probably the antique magazine from EAA.
Anyone know what the paperwork required is to put cups on and modify a shielded lead for the other plugs? Doesn't sound like something they would smile on at the FAA if you just went out and did it.
Hank

Anyone got pictures of the setup using the C26, C27, or M41N plugs?

[Ragwing nut]

Re: Spark plug shield question

Those would not be legal to install. The original cups should be just a log book entry. The were made long before STC's, I consider them a safety improvement, and do not have any affect on how the aircraft operates (only the radio), should be considered a minor alteration. Legally you would have a mechanic installed plug wires though.

[waltermrich]

Re: Spark plug shield question

Can anyone tell me if there is any benifit using cups on a unsheilded mag , I use an Eisemann AM4 on the top mag with Champion M41e plugs .Would these cups sheild any noise or would the mag and wire overcome any benifit.

[paulnuss]

Re: Spark plug shield question

The cups are only for attaching plug wires to plugs at a 90 degree angle, and have no suppression capability. The shielding is in your magnetos and wiring harness, p-leads, etc.

[waltermrich]

Re: Spark plug shield question

Thank you for that explanation of ther purpose, that was not stated in other posts that I have read

[Hank Jarrett]

Re: Spark plug shield question

Not sure where you heard that Paul. The folks who use them have told me they aren't as good as actual shielded plugs, but they DO reduce a lot of noise. Haven't put mine on yet, but will be checking to see how much they help. My plane was VERY quiet with the old shielded ignition, but they don't fit under an un-bumped cowl.
Hank

[Edwin Otha]

Re: Spark plug shield question

The Breeze cups were used for radio shielding. They started to be installed about the time radios started to be common. One of my planes still uses unshielded ignition and it sounds like a popcorn machine over the radio. The cups help with this problem.
EO

[Hank Jarrett]

Re: Spark plug shield question

Before I started my firewall forward work I had some noise (with the shielded ignition) that I traced to the unshelded "P" leads. There was a LOT of noise getting to the radio from the Mag switch!
Hank