Spark Plug Wires

[scott2000]

Wondering if anyone is familiar with and or has an opinion they could share about the pros and cons of running low resistance spark plug wires. This is in context of older vehicles but any info is welcome.
I'm getting all kinds of opinions on the web for and against and they all make sense more or less.
Pretty sure my GM (sorry JR) service manual mentions a minimum resistance per foot but would have to look. I'm guessing there is a reason for this spec. Just not clear what it is.
Radio interference is one reason I've heard. Stressing the coil, etc....

 

[Rusan]

I'm not aware of a minimum resistance spec to avoid stressing the ignition coil, but I used pure copper plug wires on my extremely souped-up 351 Windsor for several years without issue. But, I was also running a HUGE, high performance coil that was no doubt intended for low-resistance plug wires.

I can say for sure that you can forget about listening to the radio (especially AM) if you're using low-resistance wires. MASSIVE interference.

 

[JohnRoberts]

The high resistance wire was used mainly to improve AM radio reception. The ignition coils output pretty high voltage (thousands of volts) so the high resistance wire is unlikely to reduce the spark energy enough to compromise ignition. I put new wires on my car about 6 or 7 years ago, because the original wires were 20 years old.

My inner motor head says use low resistance wire ruh ruh ruh...

JR

 

[CJ]

i am going to buy new wires this week, lots of options,

worried about onboard electronics like the engine control module getting messed with,

carbon burns out at the connection points from the looks of the wires i take apart,

so new resistance wires should fix that,

here is a good article>

http://www.nightrider.com/biketech/truth.htm

 

[JohnRoberts]

I do not remember what type wire I actually bought, probably resistance.

I am starting to speculate about the false alarms I get from my mail box door alarm. I get the false alarms typically around 7PM on week nights. I do not see or notice a vehicle driving past coincident with the false alarms but I would have to be looking for it. A very noisy (RFI) source might trigger my wireless alarm loop.

JR

 

[scott2000]

I've actually come across the Magnecor in my reading...

The NGK were recommended by an ex Airforce Aviation tech on one of the forums. He seems very knowledgeable and over the top when it comes to micro details..
Pretty affordable too... Cheaper than the Delco OEM I have..

 

[cyrano]

The military runs plain copper ignition wires, but they are double shielded. I never understood why, as these are expensive. A few hundred ohms will surely not yield a lesser spark at the operating voltage of an ignition system?

 

[CJ]

You get some complex waveforms , I remember looking at the scope patterns on a Sun analyzer in highschool, kind of a damped sinusoidal, (points and condenser back then) probably sensitive to loading from the wire types, provably some delay involved with inductance from spiral wrapped wires, I believe the resistance wires are many megohms but I could be wrong, have to get out the ohm meter. But your right, 30,000 kV would blast right throw 1 megohm with plenty of current to light off a cylinder.

 

[cyrano]

It's a bit more complicated.

https://www.autonationmobileservice.com/i/blog/spark-plug-wire-resistance/

Copper core wire: 1-6,500 ohms/ft
Inductive wire: 650-2,500 ohms/ft
Carbon core wire: 3,000-7,000 ohms/ft

Let's say between zero and 20 k...

These aren't simply wires. The usual ones have a fiberglass core, fi. The link above tells it all...

 

[CJ]

Here is a vid of a guy tracking down a misfire with a scope, scroll to about 5 minutes ,

I just ohmed out my Belden Premium 7mm type F wires, they went from 3.3k to 4.3 k short to long, so I just saved 40 to 60 on wires, must be a clogged egr valve,

 

[CJ]

You can use your bench scope with one of these hopefully without blowing it up.

I will receive this tomorrow for 20 bucks with 30 day prime trial,

I will be the guinea pig and let you know how it works,

https://www.amazon.com/Hantek-HT25-...JcoxxpeVnFzI5eq74Qm5HNQ5fismYg2IaAs7hEALw_wcB

 

[JohnRoberts]

That's better than probing with your finger. I recall the old lawnmower spark plug kill shorting straps that give you a dose of magneto if your finger slips off while the motor is still going.
===
Another old shade tree mechanic trick, is to look at the engine while running in complete darkness, and look for sparks coming from leaky wires.

JR

 

[CJ]

The higher the pressure in the cylinder, the harder it is to fire the spark plug, so I like the scope idea as you can check the ignition system under real load conditions, and heat too.

Somebody told me to fire up the car at night and spray Windex on the plug wires but u could not figure out how this would create a glow which is what is supposed to happen,

 

[CJ]

You can spot bad injectors with ignition secondary scope shots,