Generic plug wires?

[Luke_Healey]

I'm wanting to get a new set of wires to use with this side mount distributor cap I bought last week. Currently, I cut the ends off of a saved set of 7mm wires off of my Isuzu pickup. I have the original cap/wires that came with the car, but they misfire badly.

I think I'm still misfiring with these old truck wires too.

I have a Napa, Oreilly's, and Advance Auto here in town and am curious as to what I need to go in looking for. Part numbers or whatnot would be helpful.

I also don't understand resistor/non resistor wires and why you'd want one or the other.

So what do you guys buy when you're not ordering from the catalogs?

I just need something cheap that will fire well.


And while I'm at it, what sort of generic ignition coil should I look at? I have my hunches that the coil itself might be a bit on the flaky side.

 

[jlaird]

Get a set of Accel 3009 wires. Durn if I remember what they are for, some V8 so you get two sets for one.

Think I got them at one of the places you mentioned.

They are yellow with red cast in plug caps.

Non resister type so you can not use a radio.

 

[Luke_Healey]

Ha, yeah, my BMC AM radio is for looks only. It lights up, but produces nothing but a slight hum from the speaker.

Those Accel wires look perfect with the 90 degree caps. Thanks!

 

[racingenglishcars]

One would figure that non-resistor types allow better spark, but it is deceiving. Resistance increases the voltage the coil will produce before arcing over the plug electrodes, therefore higher firing voltage.

It's the lower voltage that produces noise in the AM frequency range. But resistance wires and consequent higher voltage requires better insulation in the rest of the system. They can start to arc inside the distributor cap or rotor, or when the wires become old they can leak through their insulation. Therefore solid wires are safer for producing a spark every time.

 

[Luke_Healey]

Ahh, it all makes sense now. I have always seen the terms thrown around, but never any explaination of why you'd opt to use one type over another (rather, I have always just replaced my wires with OEM for my other vehicles instead of cutting my own.)

Thanks for the education. I definitely don't want cross firing or arcing between the items. Everything is in close quarters in my engine bay with wires sitting on top of each other. The non resistor type sounds like what I want.

 

[Sarastro]

Sorry, but the resident electrogeek has to jump in here. Resistor wires work by limiting the current of the spark after the plug fires. They do not limit the voltage at the plug before it fires, since there is no current, and after it fires, the voltage across the spark is very low, so that isn't affected. The current, however, is a different story--the resistance limits it, and since current, not voltage is what causes electrical noise, the noise is reduced. It also limits the speed at which the current increases, once the plug fires, which also helps reduce radio noise.

Limiting the current might reduce the intensity of the spark a little, I suppose, but not significantly--once the fuel/air mixture ignites, the spark probably doesn't matter much anymore.

You really don't want to cut resistor wire--it's a kind of graphite impregnated string-like material, so it's hard to make a contact to it in the way you would with real wire. In any case, if your car isn't designed to use it, I would suggest using copper-conductor secondary wire (if you can find it!). If you can't tolerate a little popping in the radio, what with all the other noises a Sprite generates, you can minimize it with shielding and adding a capacitor to the supply side of the distributor points.

 

[jlaird]

The wire I suggested above is stranded copper wire.

Thanks for that Steve, always nice to get the professional word.

 

[dklawson]

You did say this was a side entry cap. Make sure that the wire you select will fit. I seem to remember that a good number of the Accel wire kits use 8mm wire which may not work with your cap.

The Accel wire is what I'm running and I like it. It's a wire wound metal center conductor. It's not exactly zero ohms, but it's a lot lower than resistance wire.

Regardless of whether you choose resistance wire or not, just pay attention to the plugs you buy. If you choose resistor wire... do not use resistor plugs. If you go with solid conductor wire, use resistor plugs if you want to listen to the radio.

 

[Luke_Healey]

I ended up with some other brand, but the same application (1974 GMC pickup 5.7l SBC engine)

I'm not exactly sure they are solid copper core, but I didn't want to wait two days. The wires are long enough that if I got my own crimp caps, I could easily make four complete sets of wires out of these.

They work OK. I drove about 25 miles tonight after putting my new rear wheel brake cylinders on.

I will measure the resistance tomorrow when I'm back out in the garage. I cut them as short as possible this time so they aren't flopping around the engine bay.

 

[racingenglishcars]

So Steve, what you're saying is that the resistance doesn't affect the initial voltage? I was under the impression that the resistance being in line with the spark plug gap forced the coil to build to a higher voltage before firing. I can see what you are saying now that once it sparks, the little current there is would flow right through the plug gap and the resistance prevents that. Correct?

 

[jlaird]

8 mm fits the side entry caps just fine.

 

[JerryB]

Uhhhhhh....IF 8mm fits the 7mm holes in a side entry cap, then so be it.

But it shouldn't. (round peg in a square hole type of deal)

A side entry cap will only accept and work PROPERLY with WIRE CORE wire. You cut the end of the wire square and push it down the hole all the way and then tighen up the needle pointed screw so as to pierce the wire and make contact.

You CANNOT get resistance wire (carbon or spiral) wire to work as the core will burn back and the motor will start to miss.

Short answer.....use a stack cap and a good set of 8mm spiral core wire with 90* entry to the cap boots and brass terminals and 90* plug boots with snap terminals.

 

[jlaird]

You got it Jerry but the 8mm do fit.

 

[Sarastro]

Re:

<div class="ubbcode-block"><div class="ubbcode-header">Quote:] So Steve, what you're saying is that the resistance doesn't affect the initial voltage? I was under the impression that the resistance being in line with the spark plug gap forced the coil to build to a higher voltage before firing.[/QUOTE]

The initial voltage is not changed by the resistor wire, because, until the plug fires, there is no current, so no voltage drop in the wire. So, the build-up of voltage is the same, then the plug fires. But, once there is a spark, it pretty much short-circuits the plug contacts, so the voltage at the plug electrodes is low. The current then keeps the spark alive until all the magnetic energy stored in the coil dissipates. The resistor wire limits that current, so I suspect you get a spark that is slightly weaker but lasts a little longer than if you used copper wire.

I suspect that the problem of radio noise is not so much the noise in your own car radio than the problem of 100 million cars on the road all generating electrical noise, which could hurt all kinds of radio communications. My TR4A, back in the 60s, didn't have a problem with this, nor did my parents' American cars. I know, it does happen, but it's clearly not a universal problem. And, when it does show up, there are other solutions, some maybe even more effective.