55 braided wire resistance?

[Robert J.]

Hello; My spark plugs are coated with carbon soot no oil. Looks like it is running very rich...or not firing correctly(idle is ruff). I have heard that the braided cables do not last very long. In checking them the longer ones read 20 Ohms and the Shorter ones read 15 Ohms. Does anyone know what they should be rated at? Thanks Bob

[William C.]

Re: 55 braided wire resistance?

15 to 20 thousand ohms would be reasonable, unless you are talking about the exterior braid. In that case the resistance is immaterial for the most part as it's function is to allow the radio to work. The Spark is via the center conductor inside the cable jacket. 5000 ohms for foot of length or slightly more is acceptable, assuming the ignition system is up to snuff. YOu should measure essentially an open circuit between the inner conductor and the outer braid.

[Robert J.]

Re: 55 braided wire resistance?

Thanks; I've heard that those wires don't like a lot of heat....Bob

[Jack H.]

Re: 55 braided wire resistance?

That's true of most resistance plug wires... The inner conductor is typically stranded nylon that's impregnated with carbon (done to create the wire's resistance per linear foot characteristics). Over time, due to heating and current flow, the carbon 'cooks' leaving tiny 'gaps' that cause the wire's overall resistance to climb.

That's why, even today, plug wires need to be changed out after so many cumulative miles of use. Plus, it explains why an older engine's idle characteristics become 'rough' despite the change-out of other tune up components (points, rotor, plugs)...

[William C.]

Re: 55 braided wire resistance?

Interesting comment, but in the original application they generally performed for 50-100K miles without problem. How well the reproductions meet the original design intent and execution is an open question. Today's versions in OEM applications run 100,000 miles plus.

[Roy B.]

Re: 55 braided wire resistance?

15 to 20 thousand ohms would be reasonable, unless you are talking about the exterior braid. In that case the resistance is immaterial for the most part as it's function is to allow the radio to work. The Spark is via the center conductor inside the cable jacket. 5000 ohms for foot of length or slightly more is acceptable, assuming the ignition system is up to snuff. YOu should measure essentially an open circuit between the inner conductor and the outer braid.

Can the so called carbon wires be replaced with real wires like the old days using the exterior braid ? thanks

[William C.]

Re: 55 braided wire resistance?

Yes, but the static suppression of the braid alone is much less that that provided by the resistance core (which by the way was a graphite impregnated set of rayon strands braided around a linen core. The linen/rayon core was impregnated with mutiple passes in a colloidal graphite mixture then oven dried.

[Roy B.]

Re: 55 braided wire resistance?

Yes, but the static suppression of the braid alone is much less that that provided by the resistance core (which by the way was a graphite impregnated set of rayon strands braided around a linen core. The linen/rayon core was impregnated with mutiple passes in a colloidal graphite mixture then oven dried.

So your saying I can use "wire" plug wires in the shielding but the radio will have static? That's ok with me because I use a different FM radio held under the original that I listen to. AM sucks. I've been through four sets of original's $160.00 in the last 30 years.