Riley P

Staff member
Power User
Jan 11, 2009
2000 Z51
I know it's not a real performance mod, but does anyone have experience using these plugs, GM AC Delco 41-985, or GM Performance wires, part number 12495519. What do you use and do you like it? Thanks!
I may not be able to help "as much" as you wanted but I ran a set of GM performance plug wires on my L98 GTA a number of years ago....

I wasn't happy with them and within 18 months I had to replace every one of them. Then GM told me that my expectation of longevity for a performance wire was far too high *shrug*

They might have gotten better but for my $0.02 only??? I'd go after market

Oh yeah... and they couldn't stop the number 1 plug wire from falling off either....
Oh yeah... and they couldn't stop the number 1 plug wire from falling off either....
:eek: Duct tape and bailer twine!

Well, I may check out MSD for plug wires then. For another thought, the aftermarket plugs that people have been recommending are NGK TR55IX, NGK TR-55, and some Bosche unit. I read that the TR55IX is a hotter plug than stock, so that won't work with my nitrous when I install it:D. Just kidding. I have to do more research, but I figured I would ask what people are using on their own cars and if they like it.
Stock wires are actually pretty good, but if you have to replace them the factory LS7 wire is a nice piece. My preference is for the Taylor wires.

As for plugs I like to stick to a copper core, there cheap enough-just swap them out at the beginning of every season.

TR5 is what you would need for car that's stock, TR55 has a .060 gap is too large. TR6 is one heat range colder and would be perfect for the nitrous! ;)
I believe GM specified a .060 gap originally but in 04 revised it to .040. The TR6 comes pre-gapped at .040, It wouldn't hurt to double check it though quickly. The tighter gap is preferred for "spirited" driving! ;)
You're in the right thread Brotha! Besides spark plugs/wires, air filter, and fluids including diff, oil, brakes, steering, antifreeze, trans, and clutch if it's a manual, is there anything else that I should do for a proper tune up. I bought the car in the spring, and it hit me that I do not know when all the fluids were last changed...except the oil.
Riley what did you say about those iridium plugs i have at the shop, something about 2 heat levels or something??? are they incorrect?do i need different ones?

If they will do damage i will get the correct ones before the tune is done,

P.S. Rod I now have the guy for your tune, I have mine booked already, if you want one i would suggest you meet him when you get home.

Alright, instead of me just going by what I've heard, I figured I would get the information right off the NGK website so I actually knew what I was talking about. For our cars (2000), The spark plugs you have TR55IX, are recommended. They also list other models of spark plugs you can use such as TR55GP for Platinum plugs and TZPR5A-15 for their Laser Platinum/Iridium Plug. The spark plug wire set is RC-GMX090.

No TR5 is listed, UNLESS you go to the American site. Figure that one out. If you want to hear something else that is very weird, all the spark plugs on the Canadian site are gapped at .50 where the plugs on the American site are gapped at .40. I will through them a letter to ask why this is...unless someone else knows. I'll post to links so you can see for yourself.

Canadian Link is not working, but it is not hard to find it if you google NGK.

American Site

NGK Spark Plugs

They are different plugs for sure between the two sites. The TR55IX, is P/N 7862 on the CN site where it is listed as P/N 7397 on the US site.:confused:
Nothing, it is on the list of recommended plugs. I have no idea why they would spec different plugs between the American and Canadian Vettes. Both same year, same engine:confused:. I would go with the IX's that are gapped at .40 (Part number 7397) as your car is out of the States, just like mine. The number should be on the spark plug box. I do not know why that guy I talked to said the IX's would not be as good due to the hotter range of the plug compared to our factory units. It would be nice if someone that knew this stuff better than I would speak up.
I have the TR55IX part # 7164, Does that mean anything to you or anyone else?


How do you know what the gapping is ? I cant find it anywhere on the box

They come pre-gapped at .060, I wouldn't mess with trying to gap them as the electrode is so fine it can easily be damaged. If you get the TR5IX it comes pregapped at .040.

I hope this helps!
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