Spark plug shield question

[Ragwing nut]

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

I think that is why on the L-2 the mag switch has a shield on the back side and a woven shield around the wires

[paulnuss]

Re: Spark plug shield question

The purpose of the "Ercoupe" style cups on my Taylorcraft is to turn the 90 degree angle of the installed Slick shielded harness from Slick magnetos to my M-41 plugs in the top four cylinders, without having to make bumps in the cowling. Yes the cups themselves are "grounded" to the engine and can shield the un-shielded M-41 spark plugs fairly well, but without the rest of the shielded harness I believe they would be useless in suppressing radio noise. And yes indeed un-shielded p-leads to the mag switch can also be a major source of radio noise. My set-up has worked quite well with a hand-held radio and external antenna here at Altoona, where my bright-red Taylorcraft was always "invisible" to the other traffic when I was radio-silent. I guess looking out the windows has become a lost art in modern aviation.

[Edwin Otha]

Re: Spark plug shield question

Your going to need the full monty on the ignition shielding to get the best results. A lot is gained by using the shielded P lead wires because, in most cases, the mag switch is closer to the radio than the sparkplugs.
EO