Ignition Shielding

[Scott]

Well it's winter and the hangar is cold so I've been trying to come up with a topic for conversation....

One thing I've been considering is how to shield my Bendix mags while maintaining the stock appearance of the engine and cowling. I'm looking for some ignition shielding cups, but my question is how are the connections made at each end?

Is there a different fitting that replaces the insulator at the mag end?
What about the spark plug end?

This is what I have:
http://1.bp.blogspot.com/-K4YzScdq4b...0/DSCN2503.JPG

[Hank Jarrett]

GREAT topic! I will need to look for the drawings of the owner made replacement for the Erocoupe Cups. I have the factory cups on my 41 and they seem to work pretty good on the upper plugs (using shielded plugs on the bottom). You WILL want to route your radio ant AWAY from the "P" leads and get the coax as far back as you can before attaching to the Ant. I found that laying the coax parallel to any control cables also caused some interference. We also need to find a way to shield the connections to the mags. I have a "cup" that goes over the back of the mag switch that helped with noise too. Need to get a photo.

Hank

[Hank Jarrett]

By the way, BEAUTIFUL engine!

[Guest]

Have you looked into using BG 4B2S plugs? They are shielded and approved for the A65 and more.

I put a set in my BC12D a year ago and noticed that they are shorter than the standard shielded plug.

It looked like they would fit under the cowl without needing the cowl bumps.

I already had cowl bumps installed at that time and wondered if they were needed with those plugs.

Could supply a measurement if needed.

Dave R

[Ragwing nut]

They are 2 types. a cast cup with a standard modern looking ignition end on it that come off the side of the cup, and a spun metal cup. The barrel nut is not the same thread as the spark plug, its the same as you would find on a eismann or sf bendix mag lead nut.

[M Towsley]

This has been covered so many times. Search for Ercoupe cups to find posts regarding this, including some I posted. Lots of info, you can spend all weekend reading the threads. Search box is your friend.

Here are a couple: https://vb.taylorcraft.org/forum/tay...t=ercoupe+cups

https://vb.taylorcraft.org/forum/taylorcraft/buy-sell-aircraft-parts-services-shops/9324-need-ercoupe-cans?9065-Need-Ercoupe-cans=&highlight=ercoupe+cups

[Scott]

yup saw those threads, but can't find information on how to connect shielded wire to the Bendix mags or how the inner wire connects to the spark plug.

[M Towsley]

With the cups the wire just presses against the side of the top of the plug. I have used these for approximately 7 years, never any problems with the wire movement. If I remember I will try and take a photo of how it looks..

[3Dreaming]

The spring on the end of the shielded ignition lead pushes against the side of the brass knob on the unshielded plug. On the mag end I don't remember. The shielding might simply be clamped down by the nut that secures the lead in place. There may be a special nut for the shielded leads.

[Scott]

So it's basically a standard shielded plug termination at the cup end? like this:


At the mag end, I can see it would be possible to use the bronze clip from the stock wire in the existing insulator, and expand the shield over the insulator and under the knurled nut. Would work I'm sure, it just seems a light in terms of standards. The manual I have does show a different part number nut for shielded ignition but provides no further detail on how the HT connection is made.

[lfries]

I bought a Die to cut the threads to the Bendix leads.

[3Dreaming]

So it's basically a standard shielded plug termination at the cup end?

Yes

[M Towsley]

Here is how the spring touches the end of the plug on mine. There has never been a problem and I have never had arcing as one poster in an old thread advised. I found similar pictures in my searches so there is probably more out there than you found while searching.

You will find in some of the searched posts the Ercoupe cups need to by slightly modified, the inside bottom has to have a slight relief to give the plug more thread and the threads for the spark plug lead has to have a very minor re-cut of the threads. This is covered in those older posts.

[lawheelock]

I bought my Ercoupe cups (2 for the two top cylinders that needed bumps) from Fresno air parts, a few years ago. I had to buy a die, not too expensive, to re-cut the threads so that a standard shielded ignition lead would screw onto the cup like shown in the previous post. Don't have my plane back in the air yet, but this should work with the Slick (ugh) mags that came with my engine/plane when I bought it to repair.

Larry Wheelock, N96179 BC12D

[Scott]

Have you looked into using BG 4B2S plugs? They are shielded and approved for the A65 and more.


Dave R

Thanks Dave, While the plug might fit, I can't imagine there being enough room for the wire elbow. I only have about 1/4" clearance. I'm not even sure the cup will fit.
Where did you purchase those plugs?