Spark Plug Wire Resistance


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Sep 25, 2022
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Most of the newer spiral wound wires, appears to be the good stuff, seems to run around 50 ohms per foot. Some have said that the old wires, maybe the carbon core, were thousands per foot, meaning 10k ohms for a wire. So, having a friend recently with coil overheating, I am just a bit concerned about whether the coil can heat with low resistance wires.....hmmm ??? Any thoughts on wire resistance for points coil distributor ignition. Since I do not have the OEM wires I cant compare. I am thinking that the 50 ohms per foot wires should work OK but do not know how to review coil temp in case resistance becomes a problem. I know that the main issue is on primary, with ballast or not, internal resistance or not, etc, but with the plug wires, just concerned about secondary side for the moment. thanks
I've used the monel, spiral-wound conductor resistance wires since the earlier 1970s, after hearing about them in the late 1960s. First, the Sorensen-brand "Mono-Mag" pre-made wire sets. Later, I put a set of Borg-Warner Cool-Wires on my '77 Camaro in about 1980 or so. Then a set of B-W Cool Wire II on myu '80 Newport 360 2bbl. Then a set of BW CW-2 on my 2000 Impala.

In all cases, I could tell no difference in engine performance, but knowing that the conductors in the wire were "indestructible" in nature, was a good feeling. The wires on the Camaro have been there for over 700K miles with no issues. On the '80 Newport, the #1 plug wire had a flaky terminal at the spark plug end, which I fixed when I figured out what was going on. No significant increase in ignition noise on the AM band, either.

One MAIN thing I liked about the wires for the Camaro's HEI system was that they were the same color as the OEM wires, but with more robust terminal insulators. On the others, they were the normal black wires with insulator colors which related to the OEM colors. I liked that . . . incognito if you didn't know what you were looking at.

The "icing" is that O'Reillys usually stocked the ones I need, or can get them, at a more than reasonable cost. No need for "big name" vendors, as a result.

As to "coil overheating", I've only heard of this alleged issue of late, this summer. Considering that my experience with coils has been that they are basically bulletproof unless they start to leak or similar, these blames seem a bit interesting. As if their age is starting to catch up with them?

At this point in time, it might be that some are replacing their ignition coils thinking that "newer is best" might be getting replacement coils which are substandard to OEM coils? The FEW times I thought a coil might be going away, I bought a new one with NO numbers on it, but they usually had a small foil sticker on the bottom which had "CHINA" on it, or a faint stamp of such . Even a new ACDelco coil I bought in the 1980s. So . . . any coil with no lettering or ID on it might be suspect, to me. BTW, I ended up putting the OEM production coil back on the cars I thought might be having coil-related issues.

Of late, it seems that more CONDENSERS are having issues, especially the newer aftermarket ones. Not making complete contact inside the case with the case. Causing all sorts of performance issues! A NOS new condenser fixed them all.

ONE thing on ignition coils, related by a Holley engineer at a seminar back in the 1980s . . . the ignition coil will only build as much voltage as it needs to fire the plug(s). Even if it is rated at 50KV, rather than the stock coils of about 30KV. More resistance (as in the larger gap between the rotor tip and the dist cap terminals many sought to eliminate in the early 1970s, as it was suspected to be "emissions related", makes for a hotter spark, typically. Not unlike running a .045" plug gap rather than .035". Hotter spark is supposed to mean a stronger zap to get the air/fuel mixture burnt.

Just my experiences and observations. Others might have their own, I suspect.
iirc the 68 FSM says max of 30k resistance for the plug wires (points)...later FSM 50k for electronic ignition...depending on length the new wires ranged from around 11 to 19...if coil is overheating make sure someone didn't jump out a dead ballast resistor
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Thanks for your points guys.....does not dissway me from going with the Taylor spiral wires, with 5k per foot.....thanks. Sounds like CBODY has been on the road for a bit, with a lot of eyes out.