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Spark Plug Wire Resistance, How Important is This Spec?

RedHot85Vette

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Joined
Feb 20, 2016
Messages
64
Location
Owego, NY
Corvette
1995 Red Corvette (C4, L98)
Good Day to All! I hope all are enjoying one.


When shopping around for spark plug wires, I noticed that some had specs for Ohms like, 150, 170, 300, 500-800, etc... How do these Specs effect the running of the engine, Radio Interference, EMI... how, what, why, etc... For one, I'd just like to know because I'm the curious type, and I find all of this kind of stuff interesting. Otherwise I'd just get a box of OEM wires and call it a day. Should I be concerned about those Specs when shopping for new wires, and if so, why. I can get a great deal on some 150 Ohm and 300 Ohm nicely colored 5mm wires from Accel. Not all Spark Plug Wire manufacturers list the resistance specs. Some of the ones I looked at from Accel have those specs listed.


Best Regards to All,


John
 

Kevo

Well-known member
Joined
Sep 10, 2013
Messages
46
Location
Hampton Va
Corvette
1993 torch red stripped automatic coupe
Low resistance causes EMI solid wire core or copper core wires are only used on old time antique cars and some drag cars. Most modern cars are using 7mm or larger wires. Normally they will ohm out less than 10K per foot or 15k entire wire. The larger wire diameters came as the ignition coil output increased. The 5mm wires would be for a low voltage point type ignition meaning pre 1975 OEM. Electronic ignition system have specifications secondary wires which can vary. Excessive resistance of ignition wires lead misfires, cap, rotor, coil failures along with stalling on some cars.
 

RedHot85Vette

Well-known member
Joined
Feb 20, 2016
Messages
64
Location
Owego, NY
Corvette
1995 Red Corvette (C4, L98)
skinny wires and such

Low resistance causes EMI solid wire core or copper core wires are only used on old time antique cars and some drag cars. Most modern cars are using 7mm or larger wires. Normally they will ohm out less than 10K per foot or 15k entire wire. The larger wire diameters came as the ignition coil output increased. The 5mm wires would be for a low voltage point type ignition meaning pre 1975 OEM. Electronic ignition system have specifications secondary wires which can vary. Excessive resistance of ignition wires lead misfires, cap, rotor, coil failures along with stalling on some cars.

Thanks for the response, it's very informative. Right, I get it. Low resistance and a powerful ignition coil on let's say plain ol' 5mm wires, one can expect their stereo system to be somewhat grainy. I got some Accel 5mm Wiire ($21.00!) and they swear and advertise them as anti-emi/rfi so I just have to try them.

You also gave me one very important piece of information that I never would have thought about: electronic ignitions, emission controls, and the computer. I was in the computer business many years ago when DOS was still doing most of the work before Windows. EMI Will Mess with the Computer! I live in a very small trailer home and all my electronic junk is in one small area. I know before my phone rings, usually my cell phone, that I'm getting a call. Before the phone rings I hear this buzzing, pulsed, on my computer's speakers. I have magicJack and that might be what effects my cordless phone, but it doesn't explain the cell phone. I also was in Telecommunications in the Coast Guard. Top Secret stuff along with NATO message traffic. We had to have the FBI guys or men in black come in periodically to make sure our EMI wasn't going off into space where the Russian spy ships could get it and decipher it. Anyway, You reminded me how EMI can effect the performance of my car via the computer and components attached to it.

I know that racers will use them to squeeze every spec of an ounce out of the weight of their cars. I had a Pontiac Sunbird Convertible, V6/3.1. I read about the Horsepower/Weight ratio and it's not just horsepower which makes a fast car.

And I thought "of Course!". So I started removing junk. Hood insulation, spare tire junk, trunk floor mat and cardbord stuff, nuts bolts brackets, convertible top piston didn't work, ripped out the whole electronic system, everything, used the top manually, and so on, every time I worked on it I found something to rip out, brackets and bolts that were doing nothing, or were too much for the job they were doing, I could simply use tie wraps to secure what ever they were doing... that car developed such a set of balls! I drove from Florida to Upstate NY, 31 MPG.

I intend to do the same with my 1985 Base, Base, Base and Stock as can be Corvette. The Car I bought, was just what I was looking for but better, and was probably purchased by a Senior fellow, "tight-wad", because their isn't many options. It was owned by 3 Seniors in fact. The Last Guy, the guy I bought it from, God Bless Him, he had terminal cancer, and was unloading his toys, so his wife wouldn't have to deal with them when he was gone. I got a great deal on the car. He had it professionally painted about 2 years ago and with that special UV clear coat. There wasn't a mark on it and the dirt just slid off the finish like it was all skiing.

I think maybe the only option was cruise control. Not even power door locks. I love the cloth seats. I have looked at hundreds of Vettes and maybe I saw 2 with cloth seats and they were the cloth sport seats. I think my seats are kinda rare. That's what the previous owner said. The only way to go on these older cars. No seat cracks and tears. No leather to replace. The cloth seats are Always comfy, hot or cold weather. Very Clean car and everything worked. 31 years old, 120K miles and it no way looked it.

Oh Boy does it Run. It so wants to Fly. Let's see, Options..... No glass top, like most have, I don't know what kind of radio was originally in there it was replaced by the previous owner, a nice Sony CD system, with the original Bose speakers. Other than that everything else is GM/AC Delco. He gave me a spare drivers side muffler, cause the one on the car had a small hole in it. It was a tiny little hole you could fit a cigarette in. I'm thinking about putting on some muffler eliminators. That'll reduce some weight. From the factory it has the defrosters, defoggers, etc... but I think they all do. Says it's an option but I don't think so. I have arguably the smallest amount of RPO codes on my car. Not even 2 complete lines. Ha! It's all mostly just factory, assembly line stuff. There's no code for the Cruise Control but it's in there. There's a code for the 120 AMP alternator but that's not an "option" one had to pay extra for.

Once a person starts piling on all them accessories, body kits, xmas lights, big heavy rims and tires, tons of engine bay dressings... piece by piece, the horsepower has more weight to deal with. I like to say, to give someone the vision and point, to think how their 0-60 time would be if they were carrying a big block maybe stuffed under the hatch behind the seats. Then they get the point, but it's usually too late, since they've already spent a fortune on goodies. Some of them new fangled sound systems by themselves, collectively, wires, amps, special cabinets and whatever for all that junk. It all just serves to rob performance from the car and rattle all the nuts and bolts loose.

So back to Wires, I'm going to put on them 5mm wires and see what happens. I'll use my radio as a tester. The the wires are 150 Ohm. Most all the other wires by Accel begin at 500 - 800 ohms. I guess that's a good rating for performance and anti emi/rfi. Ya know, electronics is a strong point for me, and I know all about resistance and current, but I didn't know what effect it had on the car's engine. Engineers don't just design "cool" stuff into these cars, they take into consideration the whole car. How one little thing is going to effect some other little thing. I put a lot of consideration into the engineering of my car. Engineers aren't perfect, and they have budget guidelines to stay within. Maybe some would like to use Part "A" but it cost a lot more than the lesser quality Part "B". Where Part "B" isn't necessarily a Bad Part, it's just not the Best. They might save maybe only buy a few nickels. Spread that across 50 thousand cars and...

I also have another set of wires as a backup and to compare with. They're 170 Ohms or 270... but I'll lean toward 170. I think they're discontinued. I couldn't find them anywhere or even in their catalog, but RockAuto, who specified them for my car along with other wires of course. I just had to get them. They had originally sold for about 80 bucks, I got them for $33. They're also 8.5 mm. A little on the fat side. But they look like well built wires and very shiny black: STANDARD MOTOR PRODUCTS 10125 [Spark Plug Wire] Blue Streak High Performance Wire Set; Full Set 8.5mm.

Sorry, I write a lot, and I talk a lot as well. Most of the time. Sometimes I talk a real lot, like I can't talk fast enough, and sometimes I don't talk at all. Cycles. I'm Bipolar. Was born that way. I could be a lot of fun or a real downer. I call my condition a Gift and a Curse. And it truly is but I believe it to be more a Gift.

I take Meds which helps a great deal these days. I'm 54, and didn't start treatment til 2001, didn't get the "right" meds til March 2nd, 2006, my birthday. But Now! My problem is being couped up in the house for over a year for having 6 spine operations in a 9 month period, I have an 18" incision on my spine, which parts of it had to be "re-opened" a few times. I'm fusing up 13 spine fusions. Hopefully my next follow up with my surgeon things will be looking good and maybe I could do some work on my car.

I bought that car specifically because these C4's with the clam shell front end... no fenders to lean over, low to the ground, not much reaching...! I can still "tinker" with my car. I can't do the heavy duty, twisting, bending, contorting things like I used to do, but with my "Simple" Clam Shell Honey... I can still play. I Love My Vette! There are a bunch more reasons why it's good for a person who has a 2x4 for a spine. Anyway, whenever I get a chance to talk or write... my mind and/or mouth opens up the flood gates.

I really appreciate your donation of knowledge. It was the trigger I needed to see and understand the relationship of the wires, resistance, why's, and whatfor's, with the engines and also... the "purpose"... or "job' the wires were going to be doing. Racing or cruising the streets of your tiny little town, or even just "show". That's me really except I want to get some function with my form, and you helped me to visualize and understand things better, so I can accomplish my goal... Pretty Form but without sacrificing Function... and maybe even enhancing Function... that's the Plus I'm looking for.

Best Regards, and Good Health to You and Yours,

John V. Brennan :pat
United States Coast Guard Vet, with an All American Vette (VetsVette?)
 
Last edited:

kpic

Well-known member
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Mar 29, 2014
Messages
2,292
Location
Columbus, NC/NE Georgia
Corvette
1997 boosted silver coupe
This is a pretty interesting and informative read on spark plug wires:
Truth About Ignition Wire Conductors

Please, ignore the blah, blah, blah; or we are better..

Because no matter what is advertised, Ohm's law doesn't change.
Ohm's Law
V= I x R
voltage= current multiplied by the resistance

or I = V/R

The length of the wire does come into play if the conducting material has a constant resistance value.

But, if a 12" wire has less resistance than a 6" one, then the 12" will give the greatest current flow.

 

RedHot85Vette

Well-known member
Joined
Feb 20, 2016
Messages
64
Location
Owego, NY
Corvette
1995 Red Corvette (C4, L98)
Ignition System Bible

This is a pretty interesting and informative read on spark plug wires:
Truth About Ignition Wire Conductors

You're absolutely correct. That is a fantastic read. The Very Bible of Spark Plug Wires. It'll prevent me from buying just "cool" wires and stuff and help me put together a nice ignition system that won't interfere with my other electronic junk and computer with EMI/RFI. Electronics is a strong point with me, but being an ol' timey tech, retired, disabled, a lot has gotten away from me. For me, that article was also very refreshing. I can still build a very cool looking system, but with the info contained in that article at hand, it will be a "smart" system as well.

Thank You Very Much, it was exactly what I was looking for.

Best Regards,

John :pat
 

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