jwappes

What are the best spark plugs for 2003 LS1 engine? Also, spark plug wires.If you can, name brand and part number. Thanks.

baxsom

oem. plugs and wires do not make horsepower and the stock ignition system in a LS1 can handle a lot of abuse before it needs to be upgraded. Get GM Performance red wires from GMpartshouse and either get oem plugs from your local autozone or get the NGK TR5 plugs gapped to the new spec of 40 thousandths. The new ones are iridium (or platinum been so long since I bought oem) and the TR5s are copper. Plain old copper plugs.

mjs1012

I always run ngk tr55 plugs and msd wires and they seem to be just fine.

MAC5

Ditto on the GM red wires from GMPartshouse

The stock plug is ACDelco 41-110 (Iridium) and are pregapped to .040

ArtGle

You guys are a blessing.
I was just looking at my coupe and it's got the 41-110 gapped to .040
The "Factory Service Manual" calls for .060
But somehow I just didn't trust the book again.
I recalled that there was a change somewhere sometime to the plug gap.
Thanks

Ordered new plugs from GMPARTSHOUSE

mikex7

How come the autozone site is saying this does not fit my 2000?

LoneStarFRC

Old/incorrect/incomplete information. They only show platinum (41-962) plug (also a good plug) but no AC Delco iridium.

The info on their website generally sucks. Rock Auto is MUCH better, with fewer errors.

RedZMonte

Also running Delco Iridium (NGK Iridium are a Good alternative to Delco if not available) and GMPP 8mm Red wires. The gap did change at some point. Also dont forget Plug boot grease and anti-seize for the threads.

F&Yb0dluvr

In 2012 when I bought my 01 6 speed vert with 77k miles the first thing I did was clean the maf sensor and throttle body, and changed the plugs and wires with GM Red Wires and AC iridium plugs I can remember how much smoother and more powerful it felt taking it for that first drive..

0Anthony @ LGMotorsports

Like they said above...your not going to make more HP by putting in a 2 prong, 3 prong, 4 sided, 0 ring...what ever latest plugs is on the market. The only way plugs and wires will make more HP is if they were not working before you change it.

With that being said, I don't see anything wrong with the standard copper plug. Will they go 50k, 80k, or 100k miles? Most certainly not but they are inexpensive and work in everything from your lawn mower to 1500 hp street cars.

I'm not a fan of the platinum plugs with the little 'pucks' on the tips of the plug as they tend to fall off, get ran through the engine and also change the gap of the plug.



OEM is not a bad idea, but at the same point a set of NGK TR55's from your local auto store will work just fine as well....just might have to change them ever 20k miles.

mikex7

Thanks. So these are correct even though EVERY website I've looked at says they will not fit correctly?

warlock007

someone posted on here not to long ago that GM sent out an advisory that the 41-110 were no longer the replacement for our cars, looks like it went back to original plug. will try to find link and post

http://acdelcoadvantage.saepio.com/L...13/13D-070.pdf

LoneStarFRC

AC Delco part number 41-110 is the current iridium plug listed by GM for all C5s. The GM part number for it is 12621258, which supersedes part 12571164 (AC Delco 41-985)

www.gmpartseast.com
http://parts.nalleygmc.com/

The word "fit" is a subjective and rather vague term when it comes to plugs and can therefore be sometimes misleading. Lots of plugs physically "fit" as they will screw right in to a LS1/2/3/6/7, etc but the "correct" plug (better term) is the one that also falls into a correct/appropriate heat range and gap for a given application as determined by a particular engine manufacturer.

BTrey

All I'm finding at GMPartshouse are these:

http://store.gmpartshouse.com/parts/...g%20wire%20set

There's no indication if these are the red GMPP or stock black wires and they're listed at $125 a set. Meanwhile, I found these:

https://www.texas-speed.com/p-88-gm-...lug-wires.aspx

They're $70 a set and specifically state that they're GM Performance Parts. Something doesn't seem right here ...

lionelhutz

On the GMPH website, you go to the Corvette\C5 parts list and part way down you get this #12495519 for the GMPP wires and this #12621258 for Iridium plugs. The GMPP wires are $67.

I'd run either Iridium or copper. There is/was a problem with iridium plugs p/n's for a 0.060" gapped plug. That was first specified as the gap when iridium first replaced the platinum plugs but GM later specified to use 0.040" gapped iridium plugs due to misfiring and drivability issues.