spark plug wire

SDE · Aug 22, 2017

We were at an auction. One box had a set of spark plug wires. They are 7mm suppression I think. Will they work on a Ford 9n if they are long enough?
Thank you
SDE

Janicholson · Aug 22, 2017

Suppression wires are of two sorts. Carbon based fiber reinforced wires the core of which is nylon, or Kevlar fibers with graphite carbon impregnated into them. These have about 5 to 7 thousand ohms per foot of length. They prevent radio noise from being radiated into the surrounding air and into the neighboring homes. They increase total spark voltage by adding to the resistance of the gaps at the rotor to cap terminals, and the spark plug gap. (usually not recommended for Magneto ignition, but no real issue with a distributor. The second is Magnetic suppression wires. These have a core similar to the carbon wires, Kevlar usually, with a real copper alloy wire wrapped around it in a tight spiral. This real wire conducts electricity with little resistance. It further suppresses radio emissions by the magnetism created in the coiled up conductor. It can be used with either ignition system and does cost more. Jim

Bob · Aug 23, 2017

GREAT reply, professor Jim!

As we know, there's no "solid" spark plug wires, at the very least they are multiple twisted strands.

GOOD for you to include the spiral wound around a core suppression wires, a higher dollar, but more durable alternative to fragile carbon core wires.

John T · Aug 23, 2017

Great info Mr Jim, I knew the basics of the types of plug wires but I didn't realize all the exact details. I take it the spiral wound wire wouldn't offer much pure DC resistance but inductance when current starts flowing. I was NEVER a fan of carbon core plug wires on old tractors even distributor type.

JOhn T Live from Half Century of Progress in Rantoul Illinois

Janicholson · Aug 23, 2017

Thanks Bob/John. My info came from a technical briefing when I was service manager at A Nissan dealership. And I researched it after that to get deeper into why it works. Jim

teddy52food · Aug 23, 2017

Again proving the magnetic field comes from the atoms of the material & not the current. Very little current in spark plug wires but high voltage triggers the atoms of a copper conductor to produce a huge field. The carbon wires produce little if any because carbon doesn't give a magnetic field. (wrong material) Right or wrong? Jim?

Janicholson · Aug 23, 2017

Well, wrongish. Magnetism is produced in any conductor that has electrical current flowing in it. Quantum Electro Dynamics is the principle. The amount of surrent determines the amount of magnetism. Voltage drives current. A carbon wire just makes a poor antenna for the discharge frequencies of the spark's multiple jumps. A stranded copper Wire is a good antenna for RF in the range that produces (mostly AM) interference. The wound copper on a synthetic core is tuned to suppress the RF by self dampening of the frequencies involved. Jim

SDE · Aug 23, 2017

Thank you one and all. I knew that a magneto would require a different type of wire, but before I went to all the trouble of trying to string these thru a small tube, I would make sure that it wasn't going to be a wasted effort.
TY
SDE

spark plug wire

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