Parallel Plug Wires and Cross Fire- Myth or Fact?

[MercuryMarc]

I just picked up a new dist cap, rotor, plugs, and plug wires (I had been using the old plug wires from the boneyard that I grabbed with dizzy) since my car is running rough lately.

But reading the plug wire instructions it says, "CAUTION: To prevent cross fire, be sure that the wires DO NOT run parallel, but cross each other between the plug and the distributor."

I have the current (old) wires all lined up, looking "relatively" orderly and parallel to one another. I'd hate to reinstall the shiney new ones like a zig-zagging mess of random wires- do I really need to?

Thanks-

 

[LaGrasta]

If the wires are new and no arc is occuring then it doesn't matter where or how they lay. I literally have the plug wires on my 91 Buick zip-tied together the entire distance to each plug.

 

[wsa111]

Fact, do not run consectutive firing cylinders plug wires next to each to another.

Arcing is not the issue but conduction between wires is.

Look at the spark wire routing on an early 302, the firing order is 15426378, you will see that 7 & 8 cylinder wires do no run parallel to each other. William

 

[jamyers]

Fact, do not run consectutive firing cylinders plug wires next to each to another.

Arcing is not the issue but conduction between wires is.

William's right, running two wires side-by-side can result in the non-firing wire getting an induced current from the firing wire, which can sometimes be strong enough to spark at the plug. If it's the next cylinder in the firing order, it could cause that cylinder to prematurely "go off", causing a loss in power or *maybe* even a backfire. 10-15 years ago the insulation on plug wires was bad enough that it was a problem to be aware of.

The odds of this happening with today's quality wire insulations is low, but still a possibility, hence the warning. You probably won't have a problem if you've got some good wires (lifetime warranty), but if you'll just make sure that any consecutive-firing cylinders have their wires separated from each other, you'll ensure that you won't have a problem.

I'd get some wire separators and maybe a bracket, and keep them separated that way and not worry about it. With our firing order of 153624, I can't see it being a major issue for us.

 

[Anonymous]

The odds of this happening with today's quality wire insulations is low,.... You probably won't have a problem if you've got some good wires.

VERY low.
Good wires should be a must on any car.

 

[Lazy JW]

I suspect that a top-quality set of modern spiral wound core wires would be mighty difficult to induce crossfiring in, especially in a straight six that has a more favorable firing order. Do you feel lucky?
Joe

 

[rickwrench]

As long as the spark path is clear, there -shouldn't- be a problem. If there is a high resistance situation, then there will be jumping to the nearest path to ground.
Rick(wrench)

 

[MustangSix]

This is more a problem with solid core (copper or stainless wire) wires. The high voltage can produce an inductive effect that can fire a plug. The result is a misfire.

This is not a problem with most resistor core wires, but as Bill mentioned, you have to be careful that the wires don't arc between them due to poor insulation or moisture. Runnig them parallel is OK as long as you use a good wire separater.