ignition wire failures
 

I'm looking for some expert advice on ignition wires. I have gone through 2 sets of Ford Motorsport 9mm wires in just 6500 miles. By "going through them", I mean that one of them starts to break down and I get an ignition miss. The wire resistance still reads ok, but there is definitely something breaking down in the wire because a simple wire replacement cures the problem. 3200 street miles to a set of ignition wires seems unreasonably low.

Anyone else ever have this problem? Are Motorcraft wires that bad? Or do you think something is causing premature failure?

Other info:
MSD-7 Digital box
Ford Motorcraft coil (came with the crate motor).
Standard plugs (they look fine, with no wear).
Wide cap Ford distributor

Charlie Hi You have the right coil for the 7al? You are using he blaster SS or HVC coil I would stay with the MSD wires 8.5 super wires. You are using the wire spreaders and not letting them lay on the headers. If you spray a mist of water at night you can see where the spark is coming through the casing. If you want to stay blue with the color try the 11 mm super max from moroso. Something is causing the case to break down. Did you open up the gap on the spark plugs. With this set up you can go another .010 larger. It will not hurt anything. Rick Lake

Rick,
Thanks for responding. Actually, I made a mistake in my earlier post, I have the MSD Digital-6 Plus box, P/N 6520, not the MSD-7. But in any case, no I don't have the recommended MSD coil. I am using the Ford canister type coil which came with the engine from the SVO factory. It is supposedly designed for use with the Duraspark-II (?) system with the wide distributor cap, so I guessed (maybe incorrectly) that it was designed for higher output. I kept it cause it had the correct look sitting above my engine, and seemed to work.

I opened up the spark gap considerably. I don't remember off-hand how much, I will have to measure one. Wires are in looms and not anywhere touching the headers.

I haven't tried the water spray at night trick. That is a good suggestion. I will give that test a try as a diagnostic tool. Of course, it doesn't point out WHY this is happening. I am beginning to just think Motorcraft wires are not very durable, but I don't want to blame them for something stupid I am doing wrong.

Any idea why a different coil would cause the wire casings to break down? I would think that any quality performance wire could withstand the power from a standard high performance coil like this. I think the MSD coils put out more spark energy than this Motorcraft coil does.

Thanks for your assistance Rick.
Charlie

Charlie,

I think Rick is right - you should probably use the MSD coil (regular blaster coil). Remember the primary coil voltage is high at ~500 volts. The Ford coil may have the wrong primary/secondary turns ratio - too high a turns ratio and the coils puts out excessive voltage. The 7 series coil for that box is drag only - it may not have a long life, but you should be OK with a regular blaster coil.

Hope this helps,
Jim

Yes, that is very helpful. You may be on to something there Jim. I will see if I can figure out what this coil was designed for on the input wire. I want to keep a canister coil if at all possible because it retains the purist look, as you fellow ERA owners can appreciate. But if need be, I will go with the MSC coil for reliabilities sake.
Thanks guys for the advice/help. I really appreciate it.

Charlie,

MSD makes canister coils compatible with the MSD 7 series. They should drop right in.

http://www.msdignition.com

Click on products, then automotive, then coils.

Hope this helps,
Jim

Charlie 1 more thought. If you over heat the coil with a 6al or 7al or what ever, the saturation of the coil starts to break down. I may not have said this right but the spark gets weaker the hotter the coil becomes. You may need a ballast resistor, call MSD or check with Bob P at ERA. I would stay with all MSD stuff. Rick Lake