Spark Plug wire routing and induced firing

[Tom Cimino]

Back in the old days, the plug wires for #7 & #8 cylinders were kept apart from each other to prevent induced firing. Induced firing is caused when the magnetic field around one plug wire induces a current in an adjacent wire resulting in both plug firing simultaneously. Normally, not a problem. But with 7 & 8 firing one after the other, this can cause #8 to fire 90 deg too soon, which is hard on the engine because it tries to turn the crank backwards.

My question is, does this still happen, or have advances in plug wire technology eliminated the problem?

I've run the wires (#7 parallel to #8) on my 302 for many years without a problem. I'm running Ford Racing 8mm silicone wires and Duraspark II ignition.

[Rick Parker]

Tom:
I think the spiral wrapped design of the newer plug wires has for the most part eliminated the possibility of cross firing. The design eliminate the "Electrical Noise" that was prevalent with solid core wires.