Ignition wires

[408lx]

I scored some 93 date coded wires and tested them with an ohmmeter. The repair manual says no more than 7000 ohms per foot. I got one bad one at 21,500 ohms and its 32" long. Do any of you guys test wires like this and do you think it's okay?
Thanks

[Cobra Jet]

Yes, "ohming" out the wires by checking resistance as you did is the correct manner to test the wires. The lower the ohm/ft rating that is detected, the faster the energy is dispersed to the spark plug and is normally a good wire. Also, the length of an ignition wire can affect the ohms reading (common calc method: measure resistance of each wire, then divide length of the wire by 12 to get the per foot measurement. If one wire is out of the average measurement, it could be bad). 7,000 ohm/ft is common measurement, usually anything over 7k ohm/ft is bad.

Ignition wires are not lifetime parts, even if they look excellent on the outside (exterior casing). The internal core is what breaks down over time. The main core is comprised of a carbon impregnated fiberglass (this is the secondary current path), while that core is wrapped in a stainless steel alloy winding (primary current path). Not only does the secondary core break down, but the most common failure is where the plug boot attaches to the spark plug (or distributor cap terminal). The boot, even if it looks good on the outside, what happens is the internal secondary core wire or primary core wire can become detached from the metal contact within the boot (due to improper removal or tugging/pulling the boots). Such a disconnect will cause a short or an improper connection to the plug. When that occurs, there may not be any spark or a weak intermittent spark.

Now, if the internal core is bad (ie: actually broken) the plug wire is trash, as there is no way to repair the internal core wire (and retaining original length of the wire). Also if you can see visible signs of deterioration of the exterior casing (cracks, burns, melted, etc), there's no way to salvage the wire. Best way to see bad ignition wire exterior case problems - at night, in pitch dark, start the car and pop the hood (extinguish hood light) - at a distance, do a mist of windex or water over the wires, you should see visible arcing. Even without enticing an arc via water method, if the casing is very worn or damaged, you will see visible dry arcing. Do not attempt to grab ignition wires with bare hands while engine is running to determine if they are faulty, as you will immediately find out via a shocking experience....

If the connection is bad at the boot (cap end or plug end) - you can purchase an ignition wire repair kit and tool. To fix, just pull the boot off of the end of the wire (metal contact should slide through end of boot), cut/strip end of wire to expose "new core" and mate the core wire with the metal contact again, crimp, then push back into boot to seat and its good to use again.

Accel sells a crimping tool specifically for building or repairing plug wires (170036):
http://accel-ignition.com/exterior/tools.htm

If a plug wire boot is damaged, there are spark plug repair kits available and you just purchase whatever boot you need (dizzy side vs spark plug end, 90*, 45*, straight, etc).

You would be surprised at how many "bad" wire sets just suffer from disconnected contacts within the boot at the spark plug end or at the end of distributor cap due to careless removal. The easiest thing for most folks to do (and shops) is to remove the wires and toss in the trash instead of spending time to fix (as noted above).

There are numerous repair kits available at Summit Racing, JEGS, any auto parts store or via ignition component vendors online - just google "spark plug repair kit", a ton of hits will come up.

Rebuilding or fixing ignition wires is simple, if you want to take the time out to learn and/or do it.

[Z282SLO]

^^^^

Now that's a nice and thorough description. You write service manuals on the side?

[Mike S.]

Great reply, Phil.

-Mike

[BrettT]

Can't get any better then that for a reply, nicely done!

[408lx]

Thanks for the great info Phil, maybe I'll cut both ends off and ohm it out again and if the resistance is within range I will buy both ends and repair the wire.

[1993cobra]

My experience is that the boots are hard to remove and hard to replace , unless its on after market wires.

[Cobra Jet]

Thanks for the compliments fellas! Nope, I do not write manuals, but have been asked the same in the past, LOL! My tech replies can be lengthy sometimes, but I just like to be clear and precise so the reader can follow as if I were there helping in person.

------snip


As for the boot ends:
Purchase Dielectric Grease. Apply the grease to the inside of the boot as well as onto the metal contact end of the ignition wire. Once the grease has been applied, pushing or installing the wire into the boot will be very easy. It is also recommended to grease the inside of the boot where the contact is as well at both the plug and cap end. This will prevent moisture from getting into the boot as well as making future removal much easier.

Also note -
The wire end with metal contact only goes into the boots about 1"-2" (depending on actual boot type - straight, 45*, 90* etc). So, if you were to lop off the boot end from the wire (at the point in which the wire inserts into the boot), you should still have plenty of wire left without any problematic issues. Most ignition wire sets (factory or aftermarket) are cut to excessive length, so losing up to say 4" max from the total length of wire due to repair is not going to create a "short" wire.

This below instructional video shows how to build or create a custom length ignition wire. The concepts and processes are the same when repairing an ignition wire as well. Building or repairing ignition wire is very similar to working with standard electrical wire as far as stripping and crimping - easy to do. (Note: The video appears to have been produced by MSD Ignition products. I do not endorse or recommend their products.)

http://m.youtube.com/#/watch?v=S0_3GTuH ... 0_3GTuHkeU

Hope the additional info helps.

(Bonus tech info: this vid shows how to create ignition wire loom separaters out of zip ties. Works like a charm! http://www.youtube.com/watch?v=XkWyWaZn5Fg&sns=em )

[JohnLynch]

Phil I think the time has come for you to buy a 93 SVT

[escogt]

Phil I think the time has come for you to buy a 93 SVT

Agreed...