spark plugs

tmf6902 · August 16, 2003

When should I start looking to change out my spark plugs. I have 30K on it now, and I know supposedly their good for 100k, but I'll believe that when i see it. So when shoudl I swap them out for a new set? And when I do what have ya'll been using and getting good results with as far as brand is concerned. In the blazer I used to use autolites, and they seemed to work fairly well, but I heard from a mechanic that AC Delco wasn't bad either....Just to make people laugh I used to have to change out the blazer plugs before every long trip, and about every 2k, they were always nice and gunked, oiled, and crapped up. But it's always cheaper to buy new plugs then get a new engine......until i get a new engine.

tmf

Chevyfreek · August 18, 2003

I plan on changing the plugs on my 6.0L at 50,000 miles. That is a good long plug life I think. I would never go 100,000 mi like GM says they can do. I have heard that the best option is to replace them with the OEM AcDelco plugs. I have had no problems with mine so another set at 50,000 should work just fine. I also plan on having the radiator flushed and filled at 50,000 as well. In talking with the service manager at my dealer he suggested not to go the 100,000 miles on the radiator fluid even thought it is supposed to last that long.

CMNTMXR81 · August 18, 2003

Mine just turned 20k and I replaced them two weeks ago. I highly suggest you do the same. Perhaps you'll see some fuel economy return.

My plugs looked terrible. They were the proper color which means they were burning properly but the whole tip (not just the electrode) had a powedery, flakey white crap all over them. I also checked the gap on them and just like the F-Body's, gap was all over the place. One was gapped at .045 another at .065. Very inconsistent with the factory .060 recommended gap.

It ran much smoother, quieter, and I even seemed (at least in my mind) to get some fuel economy back. At least it didn't seem to burn as much in the first 1/4 tank as it had been. I also went with a non-platinum plug for more performance. If you do the same, you'll HAVE to replace them more frequently.

gmcjoe · August 18, 2003

I replaced the plugs on my 2000 GMC at 85K miles. They were burned up pretty good.

I replaced them with NGK TR55s gapped at .055 and swapped out the wires while I was at it with Taylors

Don't mind the rusty manifold

awdvkd · August 18, 2003

Try the copper electrode instead of the platinum, they work better. So what if you have to change them every 4-5K.

BDBWTE · August 19, 2003

Try the copper electrode instead of the platinum, they work better. So what if you have to change them every 4-5K.

I heard that. Screw those platinum plugs. Delco 46's where a real good plug back in the day.

CMNTMXR81 · August 19, 2003

Simple metalurgy would tell you that.

Platinum is a hard metal. As such it has a higher resistance which leads to a weaker spark (compared to a softer metal) and therefore longevity is the result. If you resist firing moreso than another, you'll last longer, right?

Copper on the other hand, is a softer, and as such more condusive to electricity. It'll create a stronger spark because it isn't as resistant. But the trade off is, they don't last as long as the softer metal burns away faster.

So for performance, copper or other soft metal is preferable. For longevity, Platinum, titanium or other is highly recommended.

BDBWTE · August 20, 2003

Simple metalurgy would tell you that.

Platinum is a hard metal. As such it has a higher resistance which leads to a weaker spark (compared to a softer metal) and therefore longevity is the result. If you resist firing moreso than another, you'll last longer, right?

Copper on the other hand, is a softer, and as such more condusive to electricity. It'll create a stronger spark because it isn't as resistant. But the trade off is, they don't last as long as the softer metal burns away faster.

So for performance, copper or other soft metal is preferable. For longevity, Platinum, titanium or other is highly recommended.

What plugs do you run in your truck CMNT.

422 SS · August 20, 2003

Mine just turned 20k and I replaced them two weeks ago. I highly suggest you do the same. Perhaps you'll see some fuel economy return.

My plugs looked terrible. They were the proper color which means they were burning properly but the whole tip (not just the electrode) had a powedery, flakey white crap all over them. I also checked the gap on them and just like the F-Body's, gap was all over the place. One was gapped at .045 another at .065. Very inconsistent with the factory .060 recommended gap.

It ran much smoother, quieter, and I even seemed (at least in my mind) to get some fuel economy back. At least it didn't seem to burn as much in the first 1/4 tank as it had been. I also went with a non-platinum plug for more performance. If you do the same, you'll HAVE to replace them more frequently.

I changed the factory plugs in my 8.1 at 55,000 miles and had the same issues.The plugs were all gapped different and covered in this chalky,crusty white crap.I went with the Champion platinum tips.They are less than $2.00 at NAPA.I like the extended service intrevals of the newer vehicles,but will never run the plugs in this truck more than 20,000 miles.They are very cheap and the 8.1 with the metal covers on the wires is a very easy job.It took about 30 minutes to do the swap and no bloody knuckles either.I don't see how GM thinks these things will go 100,000 miles on the factory plugs.

tmf6902 · August 20, 2003

Have any of you guys swapped out the factory plug wires for aftermarket? Is it worth it? I've heard that you should swap out the wires with the plugs, because they wear out too.

raventai · August 20, 2003

Have any of you guys swapped out the factory plug wires for aftermarket? Is it worth it? I've heard that you should swap out the wires with the plugs, because they wear out too.

I never have tried aftermarket wires on one of these now distributerless motors but have never noticed any large improvements in the past on other motors, generally wires should outlast several plug sets, if you have a dmm check them for resistance , look for cracking of the insulation jacket or arking/pitting/corosion on the contacts, if they look good keep using them

spec from GM manual for the 8.1

firing order 1-8-7-2-6-5-4-3

wire resistance 10,000 ohms's /foot

plug torque 15 ft-lb

plug gap .060"

raventai · August 25, 2003

well I changed mine also few things to report, first the manual was wrong, the plug wires are about 6" so by the manual they should run about 5,000 ohms but they were all right around 500, did the writer have a type-O? they were all to close in resistance and in good condition for them all to be out of spec

also my truck has 43k miles and these are the original plugs they are caked with carbon and ash don't think my truck would run if left til 100K

http://webpages.charter.net/raventai/DSCN1073.jpg

I was going to get standard plugs also but wound up going with bosch platinums as they were only 1.99 /each at advanced auto, a good price for a long lasting plug

CMNTMXR81 · August 25, 2003

Simple metalurgy would tell you that.

Platinum is a hard metal. As such it has a higher resistance which leads to a weaker spark (compared to a softer metal) and therefore longevity is the result. If you resist firing moreso than another, you'll last longer, right?

Copper on the other hand, is a softer, and as such more condusive to electricity. It'll create a stronger spark because it isn't as resistant. But the trade off is, they don't last as long as the softer metal burns away faster.

So for performance, copper or other soft metal is preferable. For longevity, Platinum, titanium or other is highly recommended.

What plugs do you run in your truck CMNT.

Bad,

NGK TR55 is what I used and is the stock heat range replacement for our plugs. Same as the LS1 and other Vortec truck engines. If you were running a blower, nitrous or something else, I'd go NGK TR6 which is one heat range cooler.

I'm glad to see I'm nto the only one with crappy looking plugs ARE!

As to plug wires, yes aftermarket plug wires work phenomenally IN CERTAIN APPLICATIONS! For our CNP ignition design, they work great. I've had both Magnacore and now run MSD wires on my LS1. You can use the same set of wires as the LS1 on 4.8's, 5.3's, and even 6.0's. 8.1's need a wire just a tad longer. I tried with a few MSD's off my Camaro and they were probably an inch too short for the Big Block.

To determine how they were better, I got my multi-meter out and measured the resistance in the wire. Stockers were 300 - 400 ohms of resistance. Measuring the MSD's were like 30-40 ohms of resistance. Big difference. Less resistance means more electrical power reaches it's end user...the spark plug. Now, certain vehicles like many of GM's front wheel drive V6 cars with D.I.S. ignition systems, primarily those in the 60 degree family do not take well to aftermarket wires and will actually fry the insides of them.