Ignition shorting - Coaxial Wire?

[djudge1845]

I have a '77 2.7 with stock ignition and CIS and likely all original coaxial wiring (from CDI, coil and distributor). I pulled a plug and when the ignition is switched on or off I see a spark, but when you crank the engine there is no spark.

I read many posts and wondered if the coax cable is shorting. I hear what sounds like a short when the ignition is turned on and off.
1. Does it sound like these wires are the problem?
2. If so, can they be purchased or do you need to make them? If they need to be "made" can you explain or show what you have done?

[djudge1845]

Bump

[PaddyPorsche]

Had a similar problem with '75 2.7. Managed to source cable at electrical component shop (Maplins, in Ireland and UK, maybe Radio Shack in US). Only partially solved problem. Eventually found bad CD box which was replaced with MSD, and wiring loom
which came with MSD, which had regular cable, not coax. Still not sure if original
electrical problems were caused by shorting coax or bad CD or if shorting in cables
caused damage in CD.

[djudge1845]

Thanks for the reply. I had both thoughts to throw away the complete box and change systems, but but choice if I can manage to map the replacement part.

After searching Pelican and Porsche Dealer leads me as the replacement harness is NLA.

Anyone out there ever made one?

[T77911S]

do a quick test on the box. run wires from A to the coil, B to 12v and C swtiched to ground.
put the lead from the coil close to ground, it sould spark when C is removed from ground.
DO NOT hold the coil wire.

i dont know if the coax is even needed, but you can find it. perhaps at an electroics shop or one online if you really want the coax stuff. MSD did not seem to think it was needed.

dont trash the old CD. you could make a spare harness for it to use in an emergency, if you go with an MSD