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Best spark plug wire size?


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Assuming you are referring to electrical wire with an insulation on it, it is difficult to day. The gauge refers to the cross sectional area of the conducting material (the copper) in the wire, but we are interested in the overall diameter including insulation, and insulation can come in various thicknesses. For most applications you will probably want an overall thickness of .012" - .014". In many instances this will mean using 30-34 gauge insulated wire, depending on the size you need for your application (are you replicating 7 mm wire for a stock engine, 8 mm for a modified street engine, or 10 mm or larger for a race engine) and the insulation thickness.

For insulated wire, the sizes you mention would be a bit large. For uninsulated wire, 26 ga = .0160", and 28 ga = .0126". In this case, 26 ga. is a bit large but might be usable for a modern drag engine, and 28 ga. would be suitable for a street engine.

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Setting aside the fact that there are multiple diameters of plug wires used in 1:1 cars, the wire's stated gauge does not reflect the outside diameter of the wire insulation.  For example in a typical Kynar 30AWG wire wrapping wire the 30AWG the conductor itself has a diameter of 0.010" while the OD of the insulation is around 0.020".  in 1:25 scale that scales out to 0.020 X 25 = 0.5" diameter in 1:1 or in 1:24 scale 0.020 X 24 = 0.48".  That would be a bit too thick for typical 1:1 plug wire, but close to some thicker high-performance plug wires.

I would say that both 26 and 28 AWG insulated wires would likely be too thick if you want the plug wires to look in-scale.

Detail Master makes some nice spark plug wires that will look in-scale in 1:24/25 kits.  Yes, that wire costs more than some random electrical wire, but they look "right".  It is one of many small details that either make or breaks model's realism.

EDIT: I was going from memory.  I corrected my post after reading Greg's post.

Edited by peteski
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9 hours ago, NOBLNG said:

This is what I use. It measures .020” which is 1/2” in scale. It looks right and that’s what counts. I see a lot of builds that look like they’ve used heater hose for plug wires.

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Anything thicker than that looks clumsy and not right.
But to be fair 0.020 = 0,5" is quite larger than ignition wires are on most cars as 0.5" is 12.7 mm, the MSD ignition wires om my Ford 390 based 445 stroker engine I just built and put in my 1963½ Galaxie are 8.5 mm wich equals 0.33" (0.014 in 1/24th scale), but some things looks better slightly overscale so it really doesn't matter...as long as it looks right by the eye it works.
I use Detail Master 0.016 wire for my scale ignition wires, what gauge that equals to I have no idea.

Edited by Force
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4 minutes ago, Force said:

I use Detail Master 0.016 wire for my scale ignition wires, what gauge that equals to I have no idea.

That is also what I recommended.  They look "in-scale" because they are.  The actual gauge of the conductors inside the insulation really doesn't matter.  The only negative thing about those Detail Master wires is that the insulation is made from very slippery plastic (Teflon?) so glues do not hold it well.  I suppose if someone wanted to measure the gauge of the conductor, they could strip the insulation then use a caliper to measure the diameter.  There are charts online which cross reference diameter to gauge.

Actually Charlie (a member here) From ProTech Model Products also sells wire similar in diameter to the detail Master wire.

I was also told to look for tonearm wire for turntables (record players) on eBay.  That is supposedly also very fine wire, but I never really looked for it.

 

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2 hours ago, peteski said:

I was also told to look for tonearm wire for turntables (record players) on eBay.  That is supposedly also very fine wire, but I never really looked for it.

It's 36ga., but I am unsure of the O.D. I agree regarding the DM wires. I think they're probably Teflon, as well--and they're very difficult to glue!

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6 hours ago, Force said:

But to be fair 0.020 = 0,5" is quite larger than ignition wires are on most cars as 0.5" is 12.7 mm, the MSD ignition wires om my Ford 390 based 445 stroker engine I just built and put in my 1963½ Galaxie are 8.5 mm wich equals 0.33" (0.014 in 1/24th scale), but some things looks better slightly overscale so it really doesn't matter...as long as it looks right by the eye it works.

Your math is correct. The difference in 1/25 scale between my 1/2” wire and your proper 8.5mm wire is 0.0068” which is pretty much undetectable by the naked eye. Like you said…if it looks right, it works. Anything much larger looks cartoonish in my mind.

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18 hours ago, NOBLNG said:

Your math is correct. The difference in 1/25 scale between my 1/2” wire and your proper 8.5mm wire is 0.0068” which is pretty much undetectable by the naked eye. Like you said…if it looks right, it works. Anything much larger looks cartoonish in my mind.

I agree.
And if the wires are to small it doesn't look good either.

Edited by Force
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On 8/2/2022 at 3:21 PM, NOBLNG said:

This is what I use. It measures .020” which is 1/2” in scale. It looks right and that’s what counts. I see a lot of builds that look like they’ve used heater hose for plug wires.

I use 30 AWG wrapping wire also. It looks right to me.

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13 minutes ago, deuces wild said:

Is there a company that makes 32 gauge wire???...

Sure, 32AWG and smaller. That is what Detail Master wires are.  The problem is that those companies are geared to deal with industries, not with individual sales.  So someone like Detail Master or ProTech figured out what companies make the wire then buy the wire in bulk, and repackage it in small lengths for hobbyists.

If you could find out the wire manufacturer's info and bought the wire in bulk (like 1000' at a time) then you would have the wire for much cheaper cost per foot than what the Detail Master charges. But then what would you do with a 1000' of single color wire?  Cut it up, package it and sell it to the hobbyists?  That takes time and money.

 

We should be glad that there are Detail Masters and ProTechs selling the fine wire in small quantities (for a reasonable price).  In the past I needed a larger quantity of the ProTech ignition wire to use for a model RR project (actually using the wire in its intended purpose to conduct electricity), and he was willing to sell me the wire in longer lengths  than what he normally sells for a slightly discounted price.

Edited by peteski
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