Wire replacing

2k2TahoeSS · January 9, 2003

I read in some magazine that once you get new headers its a good idea to replace the wires. why is this? Thanks

Ben

gandolphxx · January 9, 2003

Depending on the headers you may need to reroute the wires and you also may want to get better quality wires - higher thermal insulation at the same time.

CMNTMXR81 · January 9, 2003

While you're there and you have stuff removed, why not?

In our situation, re-routing them isn't an issue, it's more of a performance issue.

When I replaced my stock ones with MSD wires, there was a huge difference in resistance between a stock wire and an MSD wire. Less resistance in the MSD means more power/electricity is delivered to the plug.

Tjwong · January 11, 2003

Typically if you get a decent set of headers from TOG's, Banks, Doug Thorley, Hooker Super Comps, JBA and others, you won't really need to replace your wires. Hedman has a El-Cheapo line of headers with thin wall tubing and thin flanges, we installed a set for a customer and had to change the wires because there was not adequate clearance between the tubes and the wires. I ended up using a set of Ford 460 wires in a GM 454 application. The Ford wires have the correct offset and was the correct lengths to work.

Banks and TOG's has enough clearance on a 454 application that I was able to use the factory plug wire tin heat shields as well. So alot depends on the maker of the headers, but generally if you purchase a high quality set clearance is not a problem. Most manufacturers of high end headers for trucks knows that its a high heat enviroment and takes that into consideration when developing their products.

Other than that there is no real need to replace your factory wires. GM/Packard wires are of very high quality. Packard wires are specified by GM to be rated at <700 ohms per foot. The insulation quality is as good as any aftermarket wire, as well as its heat rating.

Just remember this, a spark plug only requires X amount of voltage to fire across the gap. A typical CNP (coil near plug) ignition coil can deliver approximately 50kv open circuit. Meaning if you disconnect the plug wire from the plug the coil can deliver in excess of 50,000 volts. Under normal conditions it take less than half of that to fire a spark plug under all operating conditions of your engine.

Your GM CNP coil is a minimum of a 50mH rated coil. A henry is a unit of inductance in a coil and its inductance which makes the spark from your coil. That OEM coil is as good or better than any aftermarket coil made.

Most CNP wires are 12" long or less, at that voltage level do you think a couple hundred ohms are going to make a difference? Its all hype and marketing. I can gurantee you that if I take a K-mart special wire 3 feet long and coil it up next to your spark plug its just going to keep right on firing along with the rest of them.

Don't get me wrong there are some real cheap junk out there for spark plug wires. What I am saying is that the OEM Packard wire is a very high quality wire. And unless its been damaged there is no sense in replacing them. In my personal 1995 Corvette with a 396 CID LT4 that is supercharged I run the factory packard wires. I have never had a ignition related problem that was caused by wires unless it was damaged or broken.

I laugh at installations where people have purchases these outragously fat plug wires from 8.8mm on up to 10mm wires now, I laugh because none of these wires fit into the OEM looms and wires are hanging in the open and the engine compartments looks like a K-Mart mechanic had been in their engine compartment.

mnstrmdnss · January 12, 2003

hey, tjwong, bieng a technician that sees cars all day, i can tell you that for the most part, gm/packard wires suck!!!, maybe in your truck applications were the wires are seperated from one another they seem fine, but in gm cars(2.2L,3100,3400 V6's), gm stupidly wraped the wires in that plastic "conduit", which every car that comes through my shop, including my moms malibu(which has only 10,000 miles on it), has significant signs of carbon-tracking(cross-firing) across the wires, no matter how old the motor is. this tells me that they are not very well built, having poor insulation. id just rather stick to great products such as accell or MSD.

Tjwong · January 13, 2003

Well, I may not be a tech any more but I was for many years a GM Tune up guy and also having spent a few years as a GM warranty rep as well. I have spent nearly 30 years in the automotive field but thats not the point.

It sounds to me like you see a problem that is specific to certain model GM cars where the wiring is perhaps damaged mechanically. I appears from your description that the wires inside the conduit are being damaged mechanically because of faulty installations and not actual breakdown of the wire itself.

If what your saying is true that the insulation qualities of Packard cable is at fault I would surely see much more failures in all models rather than just ones where there is wires are encased in plastic. I was working for cadillac when the HT4100 engine was released and all of its ignition wiring was encased as well. Back then we had very few plug wires going bad.

I am presently part owner of three general repair shops in our area and sure we see and replace a lot of plug wires. But these that get replaced has been due to corrosion, corruption by chemicals such as fuels and oils can carb cleaner, and the main cause of failure being mechanical. Mechanical failure would include cut wires, cut boots or burnt boots or wires. Very few are replaced because the conductor failed or the inuslation was bad.

If the Packard wires were generally bad I would see a lot more failures in all series of GM cars and we don't, not when I was working full time for GM and not in our shops. And if there are continued problems with Packard wires GM would get an alternate supplier of wire.

And no I am not working everyday in the shops. Like I said I am a partner. I am a self employed electrical engineer working in Pulp and Paper. I got sick of everyday customer complaints and repairs. Now I just dabble in high performance stuff mainly dyno tuning and PCM tuning in GM cars. We do a lot of tuning on Vetts and F bodies and for the most part when people ask what wires to install I always tell them the stock GM wires. They fit and they work fine as long as they don't get burnt on headers, but that statement applies for all wires.

So how many wires do you replace in the trucks? Seeing how the new LS1 style engines that are used now all employ CNP ignition like what is on my 8.1L, have you seen any failures yet? My buddies dealership don't stock to many plug wires for the LS1 series engines, and thats because they don't sell many of them. If you are working for a dealer then you know how your parts department works, they only stock what moves.

My main point is, if it ain't broke don't fix it. And also that there is a lot of hype and marketing in plug wires and why waste money on hype. And no don't buy el-cheapo K mart wires, get at least Belden wires if you go after market. And don't beleive it when wire manufacturers tell you that theirs deliver more spark energy to a spark plug with their wires, its all HYPE. If you don't beleive me use your diagnostic scope and look at the voltage levels of your secondary parade display. Install a couple after market wires and see if there is a difference, between the cylinders that have stock wires and the ones with aftermarket wires.

CMNTMXR81 · January 13, 2003

Certain GM/Packard wire designs suck. Others will last longer than what you own the vehicle for.

Many 60 degree V6 applications (2.8, 3.1, and specifically the 3.4L DOHC V6...the dreaded "X" motor) are notorious for chunking wires as their D.I.S. ignition systems would simply fry them. There was also a faulty design on the "X" motor wires that until recently (a year or two ago, considering GM stopped using this motor in 96) they hadn't had an updated design on that helped eliminate the problem.

There are other benefits to aftermarket wires besides resistance issues. benefits such as knowing when the boots "snap" on with an audible click and colors.