[TriumphMan]

Found buildup of rust on one spark plug terminal, so changing out for new(ish) plug wires that I don't know if will work. So the question.

ONAN uses/mentions 7mm copper-wire core wires for spark. The motor is a P220G/I which is an electronic ignition.

I found some older, but good automotive performance silicone-core plug wires in 7mm that I used on a performance engine I once had.

Would silicone-core wires work as replacement of the copper-core wires, if the coil end of wires were changed to the ONAN coil nipples and boots to fit properly?

Del

 

[tomw0]

The wires don't care whether they are used on a Onan or a Hemi. The amps are tiny, but the voltage is in the thousands. If well insulated, the spark will follow the conductor.
The only thing silicone core wires do is limit the amperage as they are considered 'resistor' wires. I think.
If you can get a silicone core wire to attach to the fittings nicely, it should work. I always had a problem where the core seemed to disintegrate whenever I would try to work with them. Even trimming back the insulation to gain access to the conductor was not within my skills. That was a while ago, so maybe they have improved the 'carrier' in the center from the 'fabric' or 'twine' they used before.
tom

 

[TriumphMan]

Thanks Tom. After putting out the question, I found a few articles on people using silicone or graphite core type wires on their mower engines, along with a website that spoke of how suppressed type wires worked and why they're either good or bad depending on the application. They said that they will work, but they also needed replaced sooner due to quicker breakdown of the core from vibrations, heat and time, compared to copper core wires which can last almost indefinitely as long as the insulation jacket(s) aren't cut or the ends don't produce stray arcs to ground.

Some even had worse running of engine over short periods of time. Once they swapped back to the older style of metal core type wires, they found the engines ran smoother and better in many instances due to less resistance of the voltage going through the wire to the plug.

I did some testing of a couple wires before I cut and again after I modified and found that with using silicone/graphite type wires the longer the wire, the more resistance it has per foot in length, which really isn't good when one wants a good proper spark. So for the ONAN's having different lengths of plug wires, that resistance can mean the short wire could give the plug a good spark, while the longer wire could make for a weaker spark and imbalance of power by not burning all the fuel in the cylinder.

I did do the mods to the performance wires I have, but I'm gonna also order some good old fashioned metal core wires that are pre-made for the ONAN.

I could make my own plug wires from a parts # list I found, but I found a good price on plug wires for a few dollars more by the same manufacturer that I'd be getting the parts through from NAPA.

I've got my ONAN torn apart right now getting ready to order a new ignition control that I traced down from all other tests, that had gone bad. What's a couple extra bucks for some new wires.

Del

 

[Tractor-Holic]

Most every small engine with a magneto I have fooled with had spark plug wire with a stranded stainless steel looking core wire inside them..

I suppose carbon core "car" plug wires might work OK for awhile,but the extra resistance may reduce spark intensity and cause poor performance..they wont last as long probably..

Old magneto coils I have off ancient Briggs and other engines that had the stainless steel wire core still looked new as far as the wire core went,the insulation though,was all brittle and cracked and would let sparks jump to ground instead of firing the plug..

I found a partial roll of old Packard ignition wire with the same stainless steel looking conductor at a swap meet for $5,I bought it,but found out some magneto's have the wire "made into" the coil itself,rather than have a terminal sticking out the wire can be looped thru,like most older Briggs coils...cant solder the stuff either,you just poke the wire thru the hole and twist it to secure it..

I would stick with what the manufacturer suggests..but you can experiment with the other wires and see how well they work..if the Onan has a car type 12V coil,the plug wires can probably be either kind and it wont bother it much...a magneto will likely not have enough voltage to fire thru carbon core wires for long maybe..

 

[tomw0]

After I posted, I wondered if the electronic systems would need to 'see' a certain amount of milliamps of current flow in order to properly work. I have no idea if they are picky about that or not.
Resistance 'wires' just impede the flow of current, but should allow voltage to travel without interference. You'd just not have a lot of electrons jumping the plug gap. Would that affect firing? It could. Fewer could possibly mean a slightly smaller chance of firing.
I am not an engineer, nor an EE, gave up on ME after a semester. I did replace carbon core plug wires on dad's car, thinking it would have better spark and run better. All it did was make the radio buzz... and ran no better. Went back to the old wires...
tom

 

[Ingersoll444]

Mainly the carbon core is to stop radio interference. the carbon core is more likely to fail in a high vibration environment, and its not needed... so I wouldn't plan to use it long term. Such a short wire that most OPE use, wont really make a difference in running that you can feel.. But its really not the right product for the application.