maybe it's just my bad luck, but i'm fixing to put on another set of spark wires, and MSD just don't seem to be all that. i'm still trying to get my car to run with the new engine, but now i know part of the reason why it was running like crap - and that would be cuz of (1)a bad coil wire, and (2)a bad plug wire on the pass side. both read NO resistance OR continuity. 30k on the wires... all wires "seemed" to be fine before this rebuild took place, but can wires just up and crap out like that? i didn't really think they could, but the way my luck has been lately, anything is possible. just wondered if anyone else has had bad luck with them, or knows how they could just fail. and i drove the car into the garage...

KAM

 

Sounds like rotten luck. We(knock on wood) have not had a problem with any msd product. My favorite wire is the tpis. Looks stock and holds up pretty well.

 

Just wondering something. How can they read no, resistance and no continuity? Wire that had a break in the connection from one terminal to the other would read some insane resistance or if it's outside of the limits of the device, infinity. No resistance denotes something that super-conducts. IE, No resistance means there is a connection between the two terminals and either it's smaller than the limit of the device's accuracy or super-conducting. By no continuity, you're saying there is a break in the circuit, so the two terms would be mutually exclusive, you can't have no resistance between terminals and say that the terminals aren't connected.

< / rant >

Anyways, I would look at the possibility that the wires were bent beyond their limits. Since you know they're bad, cut them open and see exactly what has happened under the insulation and tell us. I'm sure this type of problem on a popular brand like MSD would be welcome (or unwelcome as it may be) news to many. Also, what wires were they exactly?

I think the electrical system of cars is often overlooked by people tuning up their cars and building their own. I would definitely inspect the distributor and coil to make sure that it's not a problem with them or the wires didn't damage them in their failure.

We'll know more once you cut them open and show / tell us what's inside. Then we can know if they melted, insulation broke down, got bent too far, corroded somehow, stress cracked/broke due to temp ... etc etc.

 

the wires read No resitance. or continuity in other terms... if its below the level of the multimeter then teh low resistance of teh wires could be causing that

 

to answer one question i forgot to state earlier was that they are the super conductor 8.5's. according to msd, they should read 40-50 ohms per foot. when i read a couple of them out, they read "open", and if i tried checking continuity by using the ol' "buzzer" method just to check for breaks, there isn't even a buzz. know what i mean? so if i was reading on a 200 ohm scale, the resistance should show with no problems and at least give me the buzz to see if there are any breaks in the wire, right? i had a friend over who works in electronics for a career and he got the same results, so i hardly think it was an "operator error".

KAM

 

so cut them open already. I assume you've replaced them by now since they dont work at all. It would be interesting to see if the superconducters died of some sort of fault during production or if they got melted due to something flukey going on in your ignition equipment.

 

Continuity and resistance are two totally different critters. If the cable has no resistance, then it surely has continuity. My guess would be that the core has broken, therefore making the wire fail the continuity test. When you check resistance, it will come up as infinity. Some digital meters, like my bluepoint, will show this as a zero with a negative sign ( - ) in front of it. More than likely that is what was seen.

Of course this is stupid to argue about it. No continuity = POS wire. Replace it.

 

OK - got the coil wire cut open... one terminal's shield was corroded and fell off when i cut the boot open. when i cut the core, the core wire was black. when i tried to read from there to a terminal, the resistance was all over the place. where it got scraped clean to a copper apperance and checked to terminal, it read steady, checking good.

SO... what would cause the wires to "burn up"? that appears to be what happened, but something had to cause it, and i would have to say the coil, since obviously the source comes from there. now, after doing some backtracking to what i've done to the car, the coil could potentially have a bad ground. i have not verified that yet, but like i said, that potential exists. the coil receives its ground from the bracket it is mounted to, right?

and no, i haven't replaced the wires yet...

 

Sounds like a short circuit occured across the wire. Spark plugs are supposed to get a lot of voltage, not a lot of current across the wire. So perhaps what happened is the plug shield ...came into contact with the engine block and and shorted the wire across the coil to the block, instead of having the resistance of the plug to stop the current. This would fry the wire and the probably melt the shield.

The terminal shield Is something i'd look into possibly contacting part of the engine. See if you can look into the plug hole for scorch marks. Also, do you remember if the wire was still in contact with the plug when you remove it, did it come loose somehow ?


The problem is not likely to be in the coil, although the coil could be damaged now due to the short circuit. The problem seems to be in some contact with the block at the ends of the wire.


A bad ground would result in less current, and cause falts that way. A ground where you dont expect one, could cause a short circuit, which i believe is what you see here.

 

the plug wire terminals never came in any contact with any part of the block. they were always intact up until the time i initially removed them for the rebuild and when they were installed on the new engine. they were never loose and had a good hold the whole time. there were a couple of the wires that had contact with the headers, but had not burned thru (yet), so i don't know if some kind of current could have come thru there or not. i called MSD and they told me that black "coating" was applied in the manufacture of the wire, so apparently is's not from burning or too high of juice going thru it. i asked also, about the ground to coil being received thru the brackets the coil is mounted to, but he said the coil doesn't require a ground. reason i asked in particular was because i cleaned up and painted all those brackets for the rebuild. i still don't know what caused this, but another set of wires and a new coil are on the way... if anyone else has any ideas here, i'm listening...

KAM

 

The problem seems to be that the terminal shield lost contact with the terminal ...so it had a very unstable connection when plugged into the spark plug. Why it came undone could have been a fluke defect. Did the coil wire have the same problem with the terminal shield falling off?

Other than the unstable connection, there appears to be nothing else wrong with the wires.

 

the coil wire is the one we diced up in this endeavor, so with it being messed up, maybe the other 2 or 3 suffered from it, if that's even possible. but another question i have is since that is an external coil, is a ground required on it? MSD says no, i just thought it would being that it is electrical. looking at other type coils, though, it appears that it is not a requirement to be grounded...

 

It doesn't need to be grounded because all it does is act like a capacitor. It grounds momentarily when the spark in the spark plug archs to the other side of the plug and travels into the block. That's when the circuit is completed. The coil just increases the voltage, it's just one component on the path of the spark circuit. Just like how the distributor isn't grounded. The spark plug wires become the ground wires when the spark occurs in the spark plug.

 

well, thanks for setting me straight on that. hopefully this new coil and wires will take care of the ignition problems...

KAM