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Ignition wire question.

R

RayP(MI)

Well-known Member
Happens to be on a Farmall C but could
be one of many of that vintage... Has
been upgraded to 12v with 12v coil. Plug
wires are too high resistance to read
even with my super duper DVM. Indicates
that these would be resistance wires,
not solid core copper. Is this right for
this application? Wires are probably
fairly old. No history on this machine.
 
The question has been asked a number of times on the site, I think the general consensus is that a person is better to run copper or steel wire spark plug wires. Although I have seen a good number of older tractors using the newer automotive type (whatever they are called and whatever they are made of).
 
The carbon type wires do not hold up well on a tractor you need true wire plug wires unless you have electronic ignition
 
We beat this question to death on another page and FWIW (0 same as all others lol) here's my opinion:

For a basic stock 6 or 12 volt old farm tractor with battery powered coil distributor ignition NOT any electronic ignition and assuming you're not concerned with radio interference I RECOMEND WIRE CORE NOTTTTTTTTTTT SUPPRESSOR PLUG WIRES

That's my story n Ima stickin to it

John T
 
(quoted from post at 15:10:26 06/11/19) Happens to be on a Farmall C but could
be one of many of that vintage... Has
been upgraded to 12v with 12v coil. Plug
wires are too high resistance to read
even with my super duper DVM. Indicates
that these would be resistance wires,
not solid core copper. Is this right for
this application? Wires are probably
fairly old. No history on this machine.
Click to expand...

"wires are too high resistance to read
even with my super duper DVM"

Carbon-core suppression spark plug wire has a resistance per foot of length likely in the 8000 to 12,000 Ohm range, so a 2' long length should have a resistance in the 16,000 to 24,000 Ohm range, EASILY measurable by a typical DVM.

If resistance is above that range, the wire is BAD!
 
Just pull a wire out of the cap and look in the boot, should be able to see if it's a metal core or the carbon/graphite looking thread.
 
I think the issue is with your meter (or *ahem* operator), NOT with your wires. Any digital multimeter should be able to read resistances of several megohms; I doubt your tractor would run at all if the ignition wire resistance was over a megohm. As gab said, you should be able to easily identify your lead type by visual inspection.

As far as what's "right", there's no reason resistance wires shouldn't work, as long as they only have a few kilohms of resistance. Should you decide to install a Pertronix electronic conversion, resistance wires are required. Solid copper wires are theoretically more reliable than resistance, but I've had no trouble with the 20 year old resistance wires on my Ford. YMMV.
 
I think either should work. BUt resistance wires when 54 years old, full of cracks probably not gonna be serviceable... Not saying folks dont replace their spark plug wires when needed, but I am gonna say no one replaces spark plug wires till past needed.



Now question for the sparkies... which wire will give the higher spark voltage, and therefore jump the bigger gap.... copper or carbon/graphite??

Hint.. the inductor discharge vs the capacitor discharge rule....
 
> which wire will give the higher spark
voltage, and therefore jump the bigger gap.

Assuming both are in good condition, both will deliver the same voltage to the plug. Spark voltage is a function of gap distance, not plug wire resistance. Note that spark current is negligible, so there is almost no voltage drop in the plug wire.
 
solid core if points are used . Spiral wound suppression wire between the coil and distributer if a Pertronix conversion has been added .
 
solid core if points are used . Spiral wound suppression wire between the coil and distributer if a Pertronix conversion has been added .
 
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