FAQ: Which Spark Plugs & Ignition Wires should I use?

+1 on the AutoLite coppers. I change them out usually once a year (just 'cause), and the electrodes are already showing significant wear.

That driver side plug is a total PITA. I'm only 5'4" and where the car was on the lift made it so I had to stand on a big block of wood so I could get my arm up there. Any lower on the lift and the car would've been too low. Oh well. Got the plugs and wires done.

I was relieved that none of the rear wires corroded onto the plug and broke. Two of the front ones did.

Example of one job that's easier done from the top.

My arms aren't long enough.

Anyone have luck with the MSD 8mm wires? I see a few people have them but haven't really seen anything about reliability/durability.

I use a set of taylor thundervolts i paid around 40$ clearance from part source (like an autozone but canaduh) and for plugs al104s gapped to .55 in the riv and used them in my lss before , they wear out so damn fast though but there cheap as hell so i do em 3 times a year, i always notice kr reduction whenever i replace em with fresh ones !

matt270avian wrote:

Anyone have luck with the MSD 8mm wires? I see a few people have them but haven't really seen anything about reliability/durability.

I don't know about these on our cars, but my understanding is that the MSDs wires are good wires. They are completely overkill, only get them if you are going after a particular look, the stock wires are excellent.

deekster_caddy wrote:

matt270avian wrote:

Anyone have luck with the MSD 8mm wires? I see a few people have them but haven't really seen anything about reliability/durability.

I don't know about these on our cars, but my understanding is that the MSDs wires are good wires. They are completely overkill, only get them if you are going after a particular look, the stock wires are excellent.

I got them for the same price as stock wires, so I figured why not.

Update on my MSDs:

Functionality wise they work as advertised. No major complaints or downfalls here.

What really bothers me is the design of the boots. They're angled kind of weird so it's hard to keep them away from the manifolds. This angle also makes it really hard to get the boots seated all the way so it's entirely possible for one of them to fall off/come loose and cause misfires.

Another complaint is the wire separators/holders. You have to be pretty careful inserting/removing the wires because the holders will put a cut in them fairly easily.

Lastly, the wires are a bit long. Granted, they might not specifically be only for the L67, but still.

matt270avian wrote:

Lastly, the wires are a bit long. Granted, they might not specifically be only for the L67, but still.

I assume you bought the MSD's designed for the GP? They are going to be longer. The GP (or W body) has a different routing than a G body. They have to be longer....

Yep. How is the routing different on the GPs? I've never really looked....

matt270avian wrote:

Yep. How is the routing different on the GPs? I've never really looked....

For starters, the GP has those "dog bone" mounts on the front of the engine. The wires take a giant dip underneath the RF mount as soon as they leave the coils. That adds length. They just have a few more things to go around/attach to in order to keep them out of harms way.

I changed the plugs on my 97 riv yesterday. It has 90000 miles and bone stock. The ones that were installed were NGK laser irridium. They looked pretty good and I'm pretty sure they were original. The gap was still at.060. I tried to be careful when I pulled them out so I could save them but I broke the ceramic on a couple. Anyway after checking out some posts about the 3800 series 2 I decided to install conventional ac delco plugs 41601 gapped at .058. I swear that made a BIG difference in acceleration. So anyway my buddy has a 92 riv with 35000 original miles. We pulled the plugs out of it and those are worn to over .090. They were conventional plugs too probably original. We put 41601 plugs in his riv too. I noticed the spark plug wires are discolored at the coil. Maybe they were running hot jumping that huge gap on the plugs?  Has anyone ran these ac delco 41601 plugs on a supercharged riv? And if so for how long? You can get them for 1.45 at rockauto. I didn't think they were that hard to change once you figure out the right tool combination. That's four plugs for the price of one irridium. Thanks

The "Iridium" plugs are supposed to be 100,000 mile plugs. The '92 didn't have those. I'm surprised at the gap with only 35K but that's not unheard of.

Your '97 did not come stock with NGKs, somebody replaced them along the way.

That's what sucks about buying used cars you never know what has been done to them. At least they went with top of the line plugs. Those same NGK lazer irridium plugs are 7.50 each at rock auto. I'll pull one of those conventional plugs I installed after 10000 miles see how they look.

Just put in some Belden wires.  The N/A  (700949) has a different p/n than the SC (700951) applications.  Hopefully they hold up.  I kept the receipt.

I probably should have
a) read this thread 1st; and
b) pulled pin when I noticed the box said 8-cyl at the store, but only contains 6 wires.  The box has the correct p/n printed on it.

I'll report back if they fail.

albertj wrote:

AA wrote:

Well I'll be a sonuvabitch. Knowing good and well what could happen, I went and tried NAPA's Beldon brand ignition wires on my Grandpa's '96 SC Riv. He'd been experiencing that pulsating hesitation we commonly see with these engines around 100-150k, when the wires start to wear out. I knew it was the wires, so I drove 300 miles to do the job, but I didn't have time to order the OEM Packard/Delphi wires, so I bought NAPA's "best". The sales clerk told me he'd "never seen a pair returned for any reason." They weren't cheap, and I thought they would be good enough for Grandpa.

Well, they weren't good enough. After a month of trouble-free driving, got a call. Same problem again. He got it scanned - multiple misfires. The guy at NAPA is about to get his "first" returned set of Beldons from us!

I can't believe it. We preach and preach about OEM wires being the best, and I thought maybe this time I'd get lucky with a solid brand from NAPA. Nope. Sorry Grandpa, and shame on me! I'd say lesson learned, but I knew better.



Order placed. Heading out to fix the problem when they arrive. So frustrating!

PS - spark plugs looked good as new. We re-gapped them and reinstalled. The car ran completely free of misfires for 4-5 weeks.

The 3800 NA uses the same wires, they work ok in that application.  The coils on the SC Riv are MUCH higher energy and they turn the Belden wires into plasma at the crimps.

Jason, I may have jumped to conclusions after the Beldon install. After replacing the wires with a fresh set of Delco/Delpi, the problem didn't go away. We replaced all the plugs, and suspect a bad coil. I sold the Beldon wires on eBay for $25.

AA wrote:

Jason, I may have jumped to conclusions after the Beldon install. After replacing the wires with a fresh set of Delco/Delpi, the problem didn't go away. We replaced all the plugs, and suspect a bad coil. I sold the Beldon wires on eBay for $25.

Glad to hear. The Beldens were cheap at $40 cdn at Napa with a lifetime warranty. With the headers, plugs and wire are a breeze. If they crap out, I'll just get a refund and go for Delco.

turtleman wrote:

Basically my only plans in terms of modification right now is a 3.4 pulley & intake plumbing (and 180 tstat & higher flow mufflers in case it makes a real difference) and i will pretty much always be using 91-93 oct gas just depending on what station i go to. my question is do i want to use 605 or 104 plugs?

So funny..

Hey, we've all been there......

I just wanna go where Turtles going.. 11s?

It's been a while since I worked on plugs an wires.  Just put in a set of Autolite Iridiums.  The Champion Iridiums I pulled looked good but worn.  Good and worn.  Gaps had not really changed worth a darn (I replaced plugs due to time on these, no performance issues for my driving).  

I am currently running a set of Delco wires I got form Rock Auto on closeout a while back.  I bought a set of Beldens (NAPA) on the current closeout. Looked real good for $9.00 - have not checked them yet however. They are spiral-wound-wire over core.  I did not install them because (a) the Delcos are still OK and (b) for some reason I could not get the plugwire harness clip over the rear bank open.

Why not the Magnecor wires?  They were excellent wires BUT for some reason the clip over the #4 plug ablated away.  I sent them back, and got the following:

--begin--
We are sorry, we cannot accept wires for repair unless the wires are in a reasonably clean state.

At a glance, some spark plug boots seem to contain a substance that could become conductive.

Did you check the spark plug plugs for any cracks in the porcelain?

A replacement set will cost $79.20 plus postage.
--end--

I replied:
--begin--
Steve (presumably):  I apologize for sending the wires in condition unacceptable for repair.  I do not recall specific conditions stipulated in your instructions or correspondence, but just the same I'll take responsibility for overlooking that as, thinking about it, wiping the wires off takes but a moment although it might be that in some cases to do so also makes it more difficult to figure out what went wrong -- once in a while, dirt tells a significant story.  All the same, I'll take the blame.

The 'substance' in the boots would be relatively small amounts of installation lube, generally a "silicone grease."  If I remember correctly it should be something in the polydimethylsiloxane family of stable, inert lube compounds, I have a couple kinds I use on various automotive electrical connectors.

The spark plugs had *no* cracks in the porcelain, actually.  

Really, the only issue I found and thought notable upon my initial, cursory inspection was that the metal terminal in one of the coil ends, I think the #3 or #4 (I forget which at this point), had ablated.  This finding did not match other findings Magnecor posted in its helpful FAQ, bulletins, or "Gallery of faulty wires," and I had no way of knowing whether this was a condition that you could correct my any change in material or manufacturing. So out of respect for the quality and longevity that Magnecor did provide, and the impression that you might be curious about if not interested in such failure, I sent the wires back - albeit, admittedly, after  an embarrassingly long  delay on my part after our correspondence.

What I was thinking - again, after only a cursory inspection - is that an electrical characteristic of the coils combined with a connector that was a bit loose in the first place might actually be at issue here, and there might not be much that can be done about it.  GM uses a 'waste spark' system, 3 coils instead of 6, and so technically three coils are "wired backwards."  It probably does not make that much difference, as the coil works using pulsating current.  Any polarity on the primary side and any polarity on high tension side will produce the same quality of spark.  Polarity on the primary side would give bias but 12v versus 25,000+v  -  probably won't significantly impact the spark quality on the high tension side.  My guess - and this is only a guess - is that over a long time an ablation issue might present on the reverse-polarity (notionally) side of the secondary.  

Assuming an "engineering" lifetime of say 150,000 miles (say 3000-4000 hours), the "problem" occurred after the likely time frame for which the system was engineered had passed, more or less, and way after when, in my experience, the OEM wires would usually fail for other reasons (50000 to 75000 miles or 1500 - 1800 hours).  I wore out OE and aftermarket wires before installing the Magnecors. I'd have to look at my maintanance log to tell you how many and at what mileage.  The Magnecors lasted longest and but for this little issue I'd still have them installed.

I'm not a materials scientist, but I wonder if a metal change from steel to brass on every other coil terminal connection would achieve greater longevity.  I'd be a little curious to learn whether brass terminals, maybe with with steel (zinc plated) retention spring clips might have better longevity in the field conditions I experienced.

I don't really know.

Bottom line:  What do I need to know, to buy from you, and pay you to send me back those wires with the parts to fix them myself?  Please advise, thanks.
--end--

That was 29 May (5 days ago).  Have not yet received any further communication from Magnecor.

Albertj