Spark plug wire sold by the foot

[Morgan Wright]

I wonder if anybody sells spark plug wire by the foot. I plan to cut them the same length as the originals and attach the original ends to them, both ends.

 

10 mm black rubber, without any logo stamped on it (unless it says Buick). The originals have black latex rubber coatings and 0.39 inch diameter which is 9.9 mm. They are 80+ years old and decomposing, but I can tell they used to be black.

[Matt Harwood]

I buy a lot of supplies from Rhode Island Wiring. Here are their braided offerings--I don't see rubber coated but they might also have that. Could it have been black braided with a lacquer coating in '39?

 

http://riwire.com/Catalogs/sup/pages/sparkplu.htm

 

Other good places are YnZs Yesterday's Parts, Narragansett Reproductions, Harnesses Unlimited, and maybe Brillman. I've bought from all of them depending on what I need. Rhode Island is my preference because they tend to be less expensive, but it can be a hassle because they don't have online ordering--you have to call. A trade-off. Depending on what you need, one of them should have it and they all have quality products.

 

Also, 10mm is REALLY big for spark plug wires, especially if you're going to stuff them in that side cover on a Buick straight-8. Are you sure that's the size you need? Most are 7mm. Is there a chance that the wires on your car now are not original but just some really old aftermarket parts?

 

Hope this helps!

Edited May 6, 2019 by Matt Harwood (see edit history)

[dibarlaw]

My interpretation is that Morgan is using them for his 1917-1918 Buicks. The standard on size is 9mm. My 1925 is to also take 9mm wires. I changed to 7mm new Packard Electrical Co black rubber wires since I had about a 1/2 roll of it and they still have tinned coper conductors. It is difficult enough to stuff all the 7mm wires in the " high tension wire clamp"  on the side of my head let alone 9mm wires. Which the coil wire and the distributor lead is also to live in harmony under that spark plug cover on my 2 1925 cars.

[Matt Harwood]

8 minutes ago, dibarlaw said:

My interpretation is that Morgan is using them for his 1917-1918 Buicks. The standard on size is 9mm. My 1925 is to also take 9mm wires. I changed to 7mm new Packard Electrical Co black rubber wires since I had about a 1/2 roll of it and they still have tinned coper conductors. It is difficult enough to stuff all the 7mm wires in the " high tension wire clamp"  on the side of my head let alone 9mm wires. Which the coil wire and the distributor lead is also to live in harmony under that spark plug cover on my 2 1925 cars.

 

You're probably right. I don't know where I got 1939. Hopefully those sources will still be able to help. Sorry!

[Hubert_25-25]

Morgan, 

     Like Larry said, the standard is 9MM and it would be cloth covered.  I also believe black is correct for the earlier cars.  I am not sure when oak color was used.  RJL and Rhode Island will sell by the foot.  Look at RJL auto fasterners 1923-28 Buick spark plug wires.  RJL makes a real nice crimped on 90 degree end with an insulator on the wires.  I was impressed with the quality.  You could give him wire lengths and the plug wire end would be clamped on professionally.  The cap end has an easy to install metal terminal end.  

   

https://www.rjlautofasteners.com/index.html 

 

You may have the mailbox coil on the SG unit as well.   For the coil, I have a modern coil stuffed way up in the cowl and covered with a black painted piece of sheetmetal so that no one sees it.  I attached the coil bracket to a piece of 1" steel that is sandwiched behind the coil base.  The coil and bracket are from Bob's.  I have wires on my original coil which sits lower, so everything looks original, but I have a modern coil running the show.  For the modern coil, I shaved back the cloth to reveal the 7mm wire.  I then used a single 7 mm wire end to fit into the 7mm modern coil.  The wire conduit hides the cut off ends of the old coil wires.  I do like the look of the old coil on the fire wall.

Hugh

 

[Morgan Wright]

Here's a pic of what I have. For the pic, I unscrewed one of the spark plug wires at the distributor, it has fine threaded brass screws on the wire, and the stud in the cap is also brass. 

 

 

[Morgan Wright]

Couple more pretty pictures:

 

[Hubert_25-25]

Morgan, 

    The plug wire ends look like the ones RJL fasteners uses on their wires.  As for the cap end, is there a screw that goes down the inside of the wire to make the attachment?  Hugh

[Old buicks 2]

To attach the wire to those spark terminal nuts, you remove about 1/4" of the insulation.   Then insert the wire into the small hole in the nut, and then smoosh over the wire inside to form a mushroom effect.   Finally  reinstall the nut on to the dist cap.    Be careful  those nuts are HARD to find and have a special thread.

[Terry Wiegand]

On my 1916 and 1920 engines, plain Black rubber insulation was used on the plug wires.  Restoration Supply carries this Black rubber insulated wire in 7MM and 9MM sizing.  I bought a 100' spool of the 7MM wire from them because I have three cars that will be using this wire.  I chose the 7MM wire because the Rajah Spark Plug terminals are only made in the 7MM size.  The high tension wire terminals that thread onto the distributor cap posts ARE indeed a special thread.  After very carefully checking the threaded posts on the cap and the internal threads on the high tension terminals, it was determined that they are METRIC THREADS.  They are M8 x .075 which translates to a very fine thread.  I made new high tension terminals with brass inserts using the mentioned metric threads and a DuPont Cast Resin material called Vespel.  This material is almost identical in color to the old Delco Chocolate Brown Bakelite caps.  The 7MM wire fits the new high tension wire terminals perfectly as do the Rajah terminals.  Here is a photo to show the details better.

 

Terry Wiegand

South Hutchinson, Kansas

[DonMicheletti]

The original plug wiring on my '18 parts engien is smooth rubber like Morgans - not braided.

 

I'd love to get plug terminals like Morgans - mine are wrong.

 

The RJL fasteners  plug termials for the 20's Buicks are not the same

[Brian_Heil]

Based on several original Buicks I have seen, Hugh’s wires and end fittings are dead ringers 

[Morgan Wright]

More picturesque pictures.

 

 

[Morgan Wright]

Shows the remnants of rubber grommets that sealed the spark plug wire carrier pipe at the spark plug end, and the rubber washers at the distributor cap end.

[Morgan Wright]

11 hours ago, Old buicks 2 said:

To attach the wire to those spark terminal nuts, you remove about 1/4" of the insulation.   Then insert the wire into the small hole in the nut, and then smoosh over the wire inside to form a mushroom effect.   

 

It looks like they pulled a few inches of wire into the nut and packed it in, not just 1/4 inch. Then when you tighten the nut on all that copper wire, some strands even get stuck in the threads for a better connection. This pic may not show it well.

 

I was wrong when I said the connectors were brass. They look like steel, what I thought was brass was all the copper wire that got caught in the threads.

[Morgan Wright]

I thought these wires were 10 mm. When I took the wires out I found that the parts of the wire that were preserved and kept dry in the carrier pipe were 9 mm, the ends nesr the distributor were 10 mm because they were swollen with oil from exposure.

[Morgan Wright]

These are the connectors on the spark plug end that are correct for this car. They look like Hugh's but they are copper.

[Hubert_25-25]

Morgan, 

   Thanks for the detail photos.  These are very similar to what was on my car, but I wanted you to see the detail as they are different from what you are showing.     Hugh

[DonMicheletti]

Morgan,

 

Interesing that yours are brass. Mine (or remnents) are steel and totally rusted and useless

[Morgan Wright]

19 hours ago, DonMicheletti said:

Morgan,

 

Interesing that yours are brass. Mine (or remnents) are steel and totally rusted and useless

 

 

I think mine are copper coated steel. The spring clip part has to be steel, never heard of spring copper! But the spring also looks like copper so it has to be plated or dipped somehow.

 

But the whole thing sticks to a magnet, even the copper-looking part, so I thought, maybe it's copper and the end part conducts magnetism from the spring part, so I cut a tiny part of the supposedly copper part off with a hack saw, and it stick to the magnet too. So it's steel. Besides, it's much too strong to be copper or even brass. Then I took the pile of hack saw dust, and all of it stuck to the magnet, even the copper looking stuff.

 

So I did the jack knife test.......the copper scrapes off but under it is shiny new copper.

 

My conclusion is, it's made of a metal nobody ever heard of before. Same color as copper but hard, strong, springy, and magnetic, which proves these old Buicks were made by aliens from space. That's also where grade 8 steel bolts are made. Copper color, but steel.

[Robert Engle]

On my 1917 D45, The ends were very corroded ans so when I replaced the wiring, I bead blasted the plug connectors, They ended up steel colored when done.  I zinc plated them and installed them on new wires.

 

Bob Engle

[Morgan Wright]

Restoration Supply doesn't appear to carry 9 mm anymore. Just 7 mm "Packard" wire which I may have to go with.

 

I measure the copper core on my wires at 0.085 inches stranded, which subtracting 13% to convert from stranded to solid wire is about 0.8 inch solid wire which according to this is 12 gauge.

 

https://en.wikipedia.org/wiki/American_wire_gauge

 

These modern wires have more like 14 or 16 gauge or less by the looks of them. These old Buicks don't have enough voltage to push small gauge wires like modern cars do.

[Terry Wiegand]

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

[George K.]

http://www.classicpreservation.com/sparkplugwiresets.html      Take a look at this one.

[Morgan Wright]

3 hours ago, George K. said:

http://www.classicpreservation.com/sparkplugwiresets.html      Take a look at this one.

 

That says .005 ohms (5 milliohms) per foot which according to the above table is what 17 gauge copper gives.

 

My original wire cores are copper stranded wire 0.08 inches across (37 strands 0.01 inch per strand) which the table says is 12 gauge and only 1.588 milliohms per foot. I measured the coil wire which is about a foot, and that's almost exactly what I got!

 

I'm still trying to find out what Restoration Supply has in the core.

 

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.

[Frank DuVal]

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.....

[Morgan Wright]

I don't know if a 100 year old mailbox can deliver 15,000 letters.

 

https://www.youtube.com/watch?v=x46nUZ45iuM

 

That's today's video.

[Larry Schramm]

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 May 10, 2019 by Larry Schramm (see edit history)

[Robert Engle]

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

[Morgan Wright]

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.

[Robert Engle]

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

[Morgan Wright]

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.

[Morgan Wright]

That was the easy end.

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Edited May 18, 2019 by Morgan Wright (see edit history)

[carmover]

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!

[Morgan Wright]

That was the tricky end.

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