Never seen such a poor excuse for a high tension lead! Has anyone else seen anything like it?
Ignition Wiring Fail..
- Thread starter Vintage Engine Repairs
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No never have seen a single wire HT lead. Im surprised it works, especially with how fine it is.
Same here, it is surprising! I have had this same brand trimmer before with ignition issues and it’s no surprise why seeing it.
Canyon Angler
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Probably some engineer somewhere told them they could save 1/10,000 of 1¢ per million units produced by going to lighter-gauge wire and that it shouldn't matter since ignition spark is high voltage but very low amperage. Of course, that doesn't account for things like moving or vibrating the wire, or fatigue...
In the olden days, IIRC, ignition lead conductors were basically made of nothing more than cotton thread coated with conductive carbon... I'm not sure, but I think the purpose of this was to reduce RF interference for radio and TV broadcast signals.
I guess the "reasoning" is that even if you get a tiny break in the wire, if the voltage is high enough to jump a .035" gap on the spark plug, it should also be able to jump a (tiny) break in the lead.
TIG welders have high-frequency generators and spark-gap points in them to create a high-voltage spark to initiate the arc at the torch (and keep an AC arc lit through the 0V transitions when welding with AC current) and if you find that the HF spark is "weak" at the torch, on the older machines, you can lengthen the HF point gap inside the machine, which I guess increases the voltage of the HF-start spark...
In the olden days, IIRC, ignition lead conductors were basically made of nothing more than cotton thread coated with conductive carbon... I'm not sure, but I think the purpose of this was to reduce RF interference for radio and TV broadcast signals.
I guess the "reasoning" is that even if you get a tiny break in the wire, if the voltage is high enough to jump a .035" gap on the spark plug, it should also be able to jump a (tiny) break in the lead.
TIG welders have high-frequency generators and spark-gap points in them to create a high-voltage spark to initiate the arc at the torch (and keep an AC arc lit through the 0V transitions when welding with AC current) and if you find that the HF spark is "weak" at the torch, on the older machines, you can lengthen the HF point gap inside the machine, which I guess increases the voltage of the HF-start spark...
I think you’re spot on, couldn’t agree more.
Not just in olden days, many modern automotive HT leads have no wires, just carbon impregnated string in the centre and the carbon can break down and leave a gap in the conductor somewhere in the lead. Progress can be so much fun.
It’s for radio interference.
I made up a set of plug wires for my ‘53 pickup using industrial wire. Stranded stainless conductor.
At stop lights, you could hear my ignition blowing up the AM radios near me [emoji48]
I made up a set of plug wires for my ‘53 pickup using industrial wire. Stranded stainless conductor.
At stop lights, you could hear my ignition blowing up the AM radios near me [emoji48]
I don’t understand, what is for radio interference? A single strand of wire or that cotton like material the wire is coiled around?
Canyon Angler
Addicted to ArboristSite
https://www.aviationpros.com/engine...s-some-basics-on-electromagnetic-interference
Ask, and ye shall receive. Just don't ask me what any of it means!
Ask, and ye shall receive. Just don't ask me what any of it means!
Thanks mate I’ll have a read!
It's the resistance of the wire that help to attenuate radio interference, the insulation is just there to protect the core from damage and insulate the high voltage from shorting to the nearest ground. I don't think your funny HT lead was designed to lower radio interference, someone probably figured out that it was cheaper to make. REALLY stupid design.
Re-conditioned a MS661 C-M last year. The entire wiring harness was a sea of threads. After almost giving up, POGO sent me into the saw with a proper meter, and I found 3 broken wires............
Had an 038 come in awhile back. Hit and miss on running. Took me awhile to locate the problem. Seems the guy had replaced the HT lead and not the whole coil when attempting his own repair. He also denied this. lol He used an automotive carbon center automotive spark plug wire. I replaced the ingnition module. Problem solved. I might add, he wasn't happy with the cost of the new OEM module.
OT
