Morgan Wright

Spark plug wire sold by the foot

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26 minutes ago, Morgan Wright said:

If I have to buy 12 gauge wire and insulate it myself that's what I'll do. The core is what carries the electricity. That's what counts, has to be 12 gauge copper.

 

12 awg is good for 20+ amps! No way can your ignition coil supply this. So, smaller awg will work just fine!

 

You are putting waaaayyyy to fine a specification on how this whole voltage drop thing works.  Lets apply some math and ohms law:

 

Now, if you were looking at a six volt system, a few ohms means a whole lot! Primary of ignition coil might pull 8 amps. and wire from battery to coil might be 6 feet.  E=IR, 8 x 6 x .005 = .24 volts. 8 x 6 x .001588 = .076 volts. You might say this is a quarter of a volt drop vs negligible voltage drop, so the larger wire is better.

 

But at 15,000 volts, a volt or two less is negligible! Just what current do you think is in the secondary voltage of your coil? Lets just say one amp for example. E=IR, one amp times .001588 ohms is .001588 Volts! If the smaller wire is a whopping .005 ohms, about three times greater resistance, then at one amp the voltage drop is .005 volts. Now really, do you think if the ignition coil puts out 15,000 volts, that the spark plug will like 14,999.999 volts better then 14,995 volts?

 

This is why resistor spark plugs work just fine in most Kettering systems. A killohm of resistance will only drop the voltage at the plug during firing by 1000 volts (assuming 1 amp of current), so now down to 14,000 volts.....

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Posted (edited)

I agree with Frank that 12 ga wire is overkill.  For spark plug wires you could probably use 16 ga and be fine.  For spark plug wires, the most important thing is the insulation so you do not get any bleed through of the current  through the insulation from the high voltage which could cause a mis-fire.

Edited by Larry Schramm (see edit history)

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You might want to look at John Brillman for your wire.  He has 7,8,9, 10 mm wire in black and oak Lacquer coated or woven finish.  WWW.brillman.com   888-274 5562.

 

Bob Engle

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I just bought 13 feet of Packard 440. That's the stuff we used to use when making neon signs, sometimes we'd use 10 foot lengths, it was 10,000 or 15,000 volts and never failed. I used to make Jacob's ladders with the 10,000 volt neon sign transformers, just for fun. I made one on a guitar, using the guitar strings. Bzzzzzztttt.

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If you are really hung up on specifications, John Brillman will make the wire to your specs.  He makes all of his wire.

 

Bob Engle

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41 minutes ago, Robert Engle said:

If you are really hung up on specifications, John Brillman will make the wire to your specs.  He makes all of his wire.

 

Bob Engle

 

I'm not doing a restoration on this car, just want to get it running and enter into HPOF "preserve original features". The Packard 440 specs are close enough to original.

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On 5/9/2019 at 5:57 PM, Terry Wiegand said:

I'll have to respectfully disagree with Mr. Wright and the voltage on these old Buicks.  When I put the new plug wires on the '20 last year, I got bit pretty good by that old 'mailbox' coil.  My arm hurt for about 15 minutes.  A whole lotta fire in that system!

 

Terry Wiegand

South Hutchinson, Kansas

I know what you mean Terry I forgot to turn off the ignition switch on my 25 and grabbed the coil wire and it knocked the stew out of me.At least that let me know the coil was working properly!:o

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