Spark plug wire routing

[Krooser]

So I have always been of the opinion that spark plug wires sould be seperated from each other to prevent crossfiring.

For the last few years I have seen a trend on my friends dirt cars to bunch each side together with zip ties and run them from a the dizzy, under the heads then onto the individual plugs.

Do the new style plug wires afford that much shielding that it's feasable to do this? Most of the guys I see are running Scott 8mm wires...really popular with many engine shops and racers. Right around $120.00 per set depending on options.

And I'm not talkng about just the regular Joe running Saturday nights at their local track. I'm talking top teams running "money is no object" 900HP wide bore motors @ 9,000 RPM.

What do ya think?

 

[12many]

Do the new style plug wires afford that much shielding that it's feasable to do this?

What do ya think?

INO, yes. New wires make it feasible. I say any concern is just an old mindset that applied to wires of old. Now with how most are designed there’s no need for concern. Just a guess, but Nobody is likely running older oem 7mm wires with high powered multi spark ignitions. Only misfires I’ve ever seen from oem to higher perf systems was spark jumps at the cap between two adjacent towers, one plug wire terminal in the cap had corrosion in it (high resistance) And another was a cheap set of new plug wires where one was burned from resting on the header pipe at some point, but was then no longer touching but developed an occasional misfire from arcing while driving (wire flopping around getting too close at times) I’m running a Crane HI-6 ignition system with Moroso Bluemax 8mm wires, they touch each other coming out of the cap, and as they route down to the plugs. Not your 9000 rpm pro racer setup (6500rpm and strip) Never any misfires. Keep em off the headers is all I worry about.

 

[67Dart273]

^^I disagree with this assessment^^ Modern higher power ignition, even the now obsolete Mopar breakerless, increase spark energy. While SOME modern wires use technology for radio supression that is different than the old resistor wires, IT MAY BE that near magnetic fields are stronger, even though they may not "radiate" in the sense of radio noise. "Magnetic induction."

The "big two" are cylinders 5 and 7, but also keeping the wires away from the trigger wires and other small signal wires (especially with modern EFI, etc) is what is important

Run small signal wires as near as right angles when crossing high tension, keep the low voltage wiring "dressed" near the block and body--which provides some form of shielding, and keep 5 and 7 separated.

 

[12many]

Let’s not muddy up the topic. The topic is spark plug wires. Let’s not talk theory, let’s talk reality. I’ve never experienced crossfire with any plug wires touching each other, Krooser mentions racers bundling, that’s reality

 

[67Dart273]

Let’s not muddy up the topic. The topic is spark plug wires. Let’s not talk theory, let’s talk reality. I’ve never experienced crossfire with any plug wires touching each other, Krooser mentions racers bundling, that’s reality

I've never accidently shot myself in the foot with a 12ga, either but it has happened.

This is not theory. It has and does happen. It is well known "such as" MSD can cause voltage regulators to go nuts, and similar systems the plug wires can trigger themselves from the plug wires inducing false triggers in the pickup lead.

There are known issues with such as EFI DIY "kits" including Holley Sniper.

 

[12many]

I say any concern is just an old mindset that applied to wires of old.

So,
Racers turning 9000rpm on a track, running $120 plug wires that are zip tied bundled. No problems. I stated what I run ($80 Moroso) and how I run them no problems. I’ve run other systems not as powerful and no issues. What are they and I doing wrong???!!!!

 

[Bewy]

67Dart is correct.
There are a number of factors to consider. There is the thickness of the wire itself; 10mm is better than 7mm. Things such as the electrode gap, rotor gap, all contribute to the reqd voltage to ionise the plug gap. If these things cause excessive voltage build, you create the 'perfect storm', then the coupling of wires close together might cause a spark in the close-by wire.
From MSD Tech Bulletins on adjacent Cyl Crossfire: ' The cause is the type & routing of spark plug wires...'

 

[12many]

Do the new style plug wires afford that much shielding that it's feasable to do this?

Yes. It is feasible. As is obvious from what you’ve seeing some of your friends doing (and I see in my experiences) Use good wires, worry less, roll more.

 

[Rat Bastid]

Most guys don’t run enough ignition to warrant anything more than a 7mm wire. Which is sad because there are much better ignitions out there they could be using.

 

[Demonic]

It depends on the wires. I friend of mine zip-tied his solid core wires together on his E body, couldn’t figure out why it was misfiring. He called me, I came over and cut the ties. Problem solved.
He was kinda new to old cars at the time.

 

[6PKRTSE]

Zip ties work fine as long as you divide them between each wire. Kind of the same thing as using wire separators.

 

[MOPAROFFICIAL]

Well since resistance is increased with length unless you're using a solid core wire I guess then it's very micro..
I would want all my wires to be as short as possible but to also be the same length if they weren't solid core... and separated just because.

It's more of a problem with cheap wires, the arcing off each other and anything metal or ground that is. I've ninety-nine percent of the time run Taylor wires , the spiral Pros which have a little more resistance than an msd wire but are durable and don't rip apart when you pull them. I use Matco wire-pullers and the cheap ones will still rip boots and half or tear wire right out of the connector

 

[Bewy]

The resistance of the wires is far less important than some people think. GMs HEI specified 0.080" plug gaps on some engines with carbon wires that had 10k-30k ohm resistance. And it worked just fine.
Circle Track magazine did a test over 20 yrs ago of about 10 different plug wires. Different brands, but all were heli core wires, & resistance varied between each brand. The difference between the best & worst was about 6 hp [ from memory ]. The highest HP was achieved with a wire that did NOT have the lowest resistance in the bunch. Heli/spiral leads use a ferrite core, which creates an inductor. Now you inductance, capacitance & resistance in the cct. I presume this has some affect on spark profile & probably explains the results of the CT test.

 

[Rat Bastid]

The resistance of the wires is far less important than some people think. GMs HEI specified 0.080" plug gaps on some engines with carbon wires that had 10k-30k ohm resistance. And it worked just fine.
Circle Track magazine did a test over 20 yrs ago of about 10 different plug wires. Different brands, but all were heli core wires, & resistance varied between each brand. The difference between the best & worst was about 6 hp [ from memory ]. The highest HP was achieved with a wire that did NOT have the lowest resistance in the bunch. Heli/spiral leads use a ferrite core, which creates an inductor. Now you inductance, capacitance & resistance in the cct. I presume this has some affect on spark profile & probably explains the results of the CT test.

This is correct. I quit looking at resistance years and years ago because it doesn’t matter. Core, outer cover and for me the spark plug boot is far more important than resistance. And probably a couple of other things I’m forgetting right now.

 

[Krooser]

These are the wires I will likely buy but in a custom length so I can run them away from my headers... I should do a mockup soon.

Dodge Small Block 340 Wire Set OVC

I have a billet ready to run MSD dizzy that's locked out, an MSD 6T analog oval track box and I will run an E-core coil similar to the Ford style E-core.

Not sure if silicone or fiberglass sheathing is better. I guess I will call the mfg. to see what they say.

 

[DARTLARRY]

These Taylor wires are very good as well.

 

[jimjimjimmy]

These are the wires I will likely buy but in a custom length so I can run them away from my headers... I should do a mockup soon.

Dodge Small Block 340 Wire Set OVC

I have a billet ready to run MSD dizzy that's locked out, an MSD 6T analog oval track box and I will run an E-core coil similar to the Ford style E-core.

Not sure if silicone or fiberglass sheathing is better. I guess I will call the mfg. to see what they say.

Those are nice wires I usually use Firecore or Taylor but I need a new set of wires I think I will order these . What sleeve are you going to use the fiberglass or silicone ? Thanks for the link .

 

[Krooser]

Those are nice wires I usually use Firecore or Taylor but I need a new set of wires I think I will order these . What sleeve are you going to use the fiberglass or silicone ? Thanks for the link .

Dunno…likely silicone.