Hi,
 
I am not an expert, but many years ago I was taught to only ground a shield at one end.

    ----- Original Message -----
    *From:* Lynn Hanover <mailto:lehanover@gmail.com>
    *To:* Rotary motors in aircraft <mailto:flyrotary@lancaironline.net>
    *Sent:* Friday, December 18, 2009 6:07 PM
    *Subject:* [FlyRotary] Spiral core wires


         I run my sensor wires (Crank trigger distributor pick up wires or
    whatever you might use) through dash 4 Teflon lined braided
    stainless hose with the braid grounded at each end. This keeps
    noise out of the trigger circuit, and helps prevent cross fire.
    Keep primary wires away from secondary wires.

         Lynn E. Hanover