I just pulled one plug off of the 03 I have owned for about a year.

It doesn't match the part number of the plugs I purchased.
I bought the regular set of replacement plugs form a forum sponsor,

AC 41-110 part number 12621258 are my uninstalled plugs
(all arrived gapped correctly in the box)

The old plug
AC 41-985 part number 12571164

I would like to know why. What would be any reason to run this plug over the replacement plugs recommended?

As you might assume I would like to know why such a decision might be made, before I install the new plugs.

By the way, the removed plug looked dry and good on the working end, but had some crud on the threads. I assume this is some type of anti-seize.

I wasn't going to install using anti-seize, but have seen some posts who advocate the use in this job. Any advice on this?

P.S. It looks somewhat impossible to run a torque wrench on the install. Any advice? Perhaps you know of a useful torque wrench for this job. The one I have now I bought cheap to work on a bicycle, and it is only accurate plus or minus 4 percent. I am not super thrilled putting my vette under this wrench, but haven't found much beyond very similar Chinese replacements at a little better accuracy rating.

I assume I will be able to get some kind of torque reading off of an easy plug and then kind of go by feel on the tough plugs.
I am certainly open to suggestions. I already see I need to get another short extension. Tool suggestions would probably help.

Trying to get this done so I can hit a big car show in Huntington Beach this Sunday. It's a three day event, with Corvettes featured Sunday.
Thought I would go and check out some wheels and tires in person.
Probably will be a good show, no shortage of money down that way.

 

41-110 is the updated replacement iridium plugs. 41-985 are the OE platinum plugs.
Why can't you get a torque wrench on them? If you're talking about spark plug #7, then just take 5 minutes and disconnect the A.I.R. tube and you will have plenty of room for a torque wrench. For what it's worth, I used a cheap inch/lb torque wrench from Harbor Freight with no issues, it was less than $10 with coupon. I would NOT attempt to install the spark plugs "by feel" because they only get torqued to 11ft lbs and you run a GREAT risk of stripping them. And definitely use anti-seize.

 

not sure when there was a change or if gm just used what they had lying around but my car had denso irridums as OE from the factory the gm number on them is 12563707

the new 41-110 number, also appear to be denso plugs with an ac delco stamp on them

 

Oops! You're correct. The 41-974 were the platinums which were replaced by 41-985 and then 41-110. From what I'm reading they switched over to the iridiums sometime in 2002-2003.

 

had to have been 2002.

this is the oem plug from my 02 z06 when i changed them out at 90k. amazing shape for that kind of mileage. next to it is the new 41-110

the real give away that delco is using denso parts and or relabeled plugs is the ground strap and electrode. they look identical right down to the pad on the ground strap which is unique to denso

 

Wow, thanks for the help. My main concern was that the old plugs were some kind of different heat range , and why would that be on a used car.

My new concern is what type of anti seize to get . I have never used any on a spark plug before. I was thinking of just rolling with the anti seize left over from the old plug install, but if a new coat is needed, I'm ok with that.

The plugs that are coming out could well be the originals, as the car was built in 02 as a 2003, and this aligns with the explanations about the plug numbers. The old plug has a delta symbol on the top of the connector post, and the new ones have a "Z" at that location.

The car has a little bobble at idle, I'm hoping new plugs and wire will clear that up. If not, I guess the coils are next to check. In any event, it seems the new plugs are an upgrade. The red wires should look cool, and I am reusing the metal shields. I don't know if they are for radio suppression or something for heat. Perhaps both.

P.S. I was thinking about removing the air pipe, to get to the work more easily, but didn't want to deal with getting a new gasket. Is this a valid concern?

 

I had my AIR system deleted when I had my car tuned. I was able to re-use my old gaskets with the block off plates without any problem. Worst case scenario you take a trip to NAPA with the old gaskets and have them match them up with new ones (there are quite a few for different cars that will work with ours).

 

40yrs of putting spark plugs in by feel and I've never had ONE issue.

 

 

Many thanks for help with what must seem like very simple concerns.
I realize I need an editor, so again thanks to those who could deal with complicated questions about very basic stuff.

I am trying to do the work correctly, and it is taking some advancement in my repair skills. The seat of the pants stuff that was appropriate for old English sports car isn't cutting it on a modern car with "systems".

Torque readings and anti seize on plugs are new to me, but I am going to be effective working on this thing sooner or later. It's just that I am the type to needs understanding before I change my ways , so the questions are very basic for most here.
Change is challenging for me, and I certainly need corvette help, so I appreciate the interest and time offered.

For instance. I assumed that any rubber that failed when I pulled the manifold would be self evident "needed to be replaced anyway", because of the age.

I now have learned that decision was beyond poor. Going to the dealer today to , hopefully , find a little rubber elbow that isn't readily available. This is after buying 80 bucks worth of tube that replaces the rubber joint in the old part that I tore up thinking all oid rubber needs to go.

I now realize everything must be saved, GM might not offer the part. Thank god I'm not working on an airplane. Think of all the tragic headlines and roof damage .

 

The gap looks to be huge on your orig plugs. I'd say your idle bobble will be gone.

You aren't going to strip the plugs w/o a torque wrench unless you are a champion weight lifter. Use a 6" ratchet and you will be fine just good and snug. If you don't know what that feels like, go buy a torque wrench. Thread them in by hand until they stop, then use the wrench.

If your wires are original, consider replacing them. They are easy to ruin if you don't remove the plug end properly.

Antisieze is avail at any parts store. You don't need much, and keep it off the electrodes! It's conductive. And have fun getting it on your hands....it will end up on everything you touch.

Have fun.

Ron

 

I was amazed by how little 11ft lbs actually was when I was torquing the plugs, if I hadn't used a torque wrench I would have easily over torqued them. I had read enough horror stories before I did my spark plug change to persuade me to use a torque wrench..but to each his own..It costs $10 and an extra 10 seconds to know it was done correctly

 

one easy trick to apply anti seize is to use a qtip and put 2 small dabs 180 from each other on the threads.

if you buy one tub of anti seize it should last you many many years. the one i suggest getting is the permatex copper. typically parts stores sell the cheaper silver anti seize. it doesn't have the heat range and isn't as effective on exhaust studs. like i said, a tub lasts years so an all purpose anti seize is worth buying.


would be what i'm referring to

 

Changed the plugs on my truck today and I'll GUARANTEE you would never get a torque wrench on any of the plugs. You guys make too much out of installing plugs, Tighten with one hand till snug is all that's required (and anti seize). There are many vehicles you'll never, EVER get a torque wrench anywhere near a spark plug.

Bet you'd be hard pressed to find anyone at a repair place that torques spark plugs.

 

Tighten 1/16 turn after plug makes seat contact. Not rocket science.

 

It's even more amusing on how complicated some guys make changing oil too.

 

This I will agree with you on. I lifted the rear of my car the first time I did an oil change, after I saw how little actually came out and how little difference it makes in the scheme of things, I found I'd rather spend the time enjoying a cold one instead of jacking up the back of the car

 

depends on a persons skill level. many of us grew up wrenching on cars and just expand our knowledge as we age

to someone who has never worked on a car, they simply will not have that 'feel' that many of us experienced folks do. nothing wrong with using a torque wrench to learn values.

with plugs a person could use the tq wrench to do one plug, get a feel for how much force that is and then apply similar to the other plugs with an easier to use ratchet

some of us can rebuild transmissions and others are just learning how to do tune ups

 

Hey, I have plenty of torque and use them a lot but the is no need to torque every fastener on the car. Many places you can't torque a fastener. When I worked in a trans shop, the torque wrench came out on VERY RARE occasions.

 

Read this from a spark plug manufacturer --- No anti seize on spark plugs and yes use a torque wrench

http://www.ngksparkplugs.com/pdf/DYK_5Points.pdf