I have a 98 c5 with 65,000 K miles on her. I have never changed the plugs and I am the second owner. I don't know if the first owner ever did, probably not. What I need to know is, what type of plugs should I get, and how hard are they to change. I had an LT-1 in the past, which was a pain in the *** to change, how about the c5? Thanks for any advise.

 

Any advise???

 

I bought a special plug wrench recommended for C5's. The rear plugs are tight but the wrench worked OK.
Fred

 

plan on taking your time, some swivel extentions will help too.. the ngk tr55's will do the trick for you. you can get those at autozone. be sure to gap them right.

 

Here is a link with a good "how to" writeup.

http://www.c5forum.com/diy/sparkplugs.php

Stock plug is AC Delco 91-485 gapped at .040 (they come pre gapped)

 

 

I recently did mine for the first time and will pass on what I learned from experience. I hope this helps.

Parts
I used AC Delco Iridiums #91-485 $55.

I used a set of stock replacement Autolite wires for $35.
(I bought both at Advanced Auto).

Anti seize compound to put on the threads of the new plugs

Dielectric grease

Tools
5/8" Craftsman swivel socket

3 inch extension, 6 inch extension, 10 inch extension depending on location

1/2" drive Craftsman pivoting head socket wrench (21" handle) with 1/2" to 3/8" adapter

3" long piece of vacuum hose that slips over the plug insulator so you can start the threads in by hand

Mechanic gloves so you don't destroy fingers, hands, and knuckles

Helpful Hints
Change the plugs when the engine is COLD.

The rear plug on the drivers side (#7) is the hardest so get the feel of some of the easier ones before you go there.

The hardest part for me was getting the old wires off. Make sure you grab the end of the boot and yank really hard - don't worry if you destroy a wire because you have a new set.

The long handled pivoting head ratchet made the job a breeze because it gives you great control and leverage to break the plugs free & the extensions keep your hands well above the tight spots. I tried with a smaller ratchet but wasted about an hour and got frustrated as well.

Put a light coat of anti seize on the threads of the new plugs and start them in by hand as tight as you can get.

Put the socket wrench on, snug then go 1/16 of a turn.

Put some dielectric grease in both the coil end and the spark plug end of the wire and snap them on.

The total job took me 2 hours and I was taking my time.

 

So you did not have to gap the plugs? They came pre-gapped? I need a tune-up on my car too. I have a 98 with 69,000 miles. I have never changed the plugs or wires. Does anyone know when the fuel filter should be changed?

 

As MAC5 state above, they come pregapped.

I change my fuel filter every 25,000 miles - this is something I have my local dealer do because it's tucked up in the back near the fuel tanks.

 

Thanks to all for the tips. I changed them today, went with the NGK's, which were pre-gabbed already. The plugs were in pretty tight, original plugs, 69K miles. I will say, the drivers side last plug was a bitch, but I got it after working around for a while. Used some anti-sieze so they will come out eaiser next time. I did not change the wires, but they will be easy when I decide to. The LS-1 is much eaiser to do than the old LT-1, that's for sure.

 

Actually, 41-985, Iridium tipped - your originals were different, .060 gapped platinum tipped (like mine -2002) - you need a PCM update for the new .040 gapped plugs, according to corvettemechanic.com.

Lee

 

The 41-985's have been installed for 2 years and 5K miles. No issues.

The PCM flash noted is first I've ever heard on this or other forums. Can you provide the link to review this requirement?

thanks

 

Recently replaced original plugs (86k) with AC iridiums as well. Not sure how you kept the wires intact. I wrecked a couple yanking them out of there. One actually came apart way too easy at the boot. That last plug was a little crazy like everyone says. Thanks to my boys for bringing all the swivels and extensions to finish up when i got stuck.

 

Get some NGK TR55 plugs - and the only plug that may give you some fits is the #7 - just hard to reach. The use of swivel sockets help.

 

although its harder on the fingers, plugs come out easier when the motor is warm

 

I bought some NGK TR55 Iridium spark plugs, do those already come gapped or do I have to do that? I just want to make sure. I would think they already come gapped for how much they cost. I'll be changing mine this weekend. Thanks.

Manny

 

I've been running the NGKs for a couple years with no problems - or real benefits, either. They are pre-gapped. I am going with the 41-985s with a PCM update - the NGKs have .060 gap (at least mine did) and currently the stock ones are .040 - that's why you need the PCM update. I think '03s and newer already have the new plugs as delivered.

Good luck!