New LS1 Owners - Newbie Tech - What plugs should I upgrade to?

Would NGK TR55's be suitable on a pretty much stock LS1? If so, what gap, and what wires to go with?

Thanks,
James

TR55s are good and I would stick with the stock wires unless they have alot of miles on them

Tr55's gapped at .55....if you have a lot of miles i would get some msd wires.

i put GMPP wires on mine, still with stock plugs. adds maybe a little power, but theyre red, so they look nice. if youre going through the hassle of changing plugs, might as well do the wires while youre there, just for the hell of it. GMPP only cost around $50 i think.

NGK's website used to say .050 for 98, and .060 for 99 and up last time I changed mine. Gapped mine at .055 a couple years ago on the 3951's. Now they say .044 for the TR55's. Going to change mine soon and thinking about going with something different. Don't know if they changed the plug or what?

TR55s gapped @ .055 and stock wires here.


Now they say .044 for the TR55's. Going to change mine soon and thinking about going with something different. Don't know if they changed the plug or what?

Interesting. I wonder what the factory gap is on the TR55s now? They used to come gapped at .059 from NGK. But if they recommend .044 now, that would be a drastic regapping from the previous factory set gap. Usually changing the gap on a plug by that much is a no-no. So does anyone know what NGK gaps the TR55s to from the factory now?

I just bought a set of tr55's (3591's) and they were pre-gapped .044. Should I re-gap them?

My car is a 2000 and has 116k. I am getting ready to replace the plugs. i was going to go with stock plugs and wires. What is the advantage of changing wires? How much difference can they make since they are so short. About the plugs, do the NGK's really make a difference?

I just bought a set of tr55's (3591's) and they were pre-gapped .044. Should I re-gap them?

Good info. I can't imagine that .044 would be best for a stock LS1 unless the TR55 is a colder plug now. I know GM has issued a new 'factory' plug for the LS1s that has an iridium tip and comes gapped from the dealer @ .040. But that's with the iridium tip. If the NGK TR55 is still the standard tip, I wouldn't feel good about gapping it at .044, IMO.

That's why I threw out the question, my old ones came gapped at .059 also. Always thought any deviation of more than like .08? + or - wasn't good.

My car is a 2000 and has 116k. I am getting ready to replace the plugs. i was going to go with stock plugs and wires. What is the advantage of changing wires? How much difference can they make since they are so short. About the plugs, do the NGK's really make a difference?

Personally I don't see any advantage to the aftermarket wires for LS1s. The distance to the plug is so short, that the gains won't even be measureable. If you want to get some aftermarket stuff for better appearance because the stock wires are shot, that's fine. But you won't see any gains swapping out a good condition set of stock wires for an aftermarket set.

Can anyone back up that the iridium plugs need to be gapped differently than any other plugs? I have a set of NGK iridiums waiting for me at home (along with a sh!tload of other parts), and I don't want these to be the cause of any problems. I believe the site I bought them off of says they come gapped at .055 They are TR55's

Also, about the wires. Just because they are so short does not mean that they are all the same. Plug wires are typically rated in the thousand's of ohms of electrical resistance PER FOOT. Between that, and the size (8mm MSD) for example, there is a difference.

Would NGK TR55's be suitable on a pretty much stock LS1? If so, what gap, and what wires to go with?

Thanks,
James
TR55's @ .050-.055, any wire will work fine.

That's why I threw out the question, my old ones came gapped at .059 also. Always thought any deviation of more than like .08? + or - wasn't good.
.08 (eighty thousandths) would be HUGE, which is over 5/64ths. I am assuming you meant .008, (eight thousandths).

As far as the original question goes, stick with the .055 gap for the TR55s. Never install a set of plugs without checking the gap first on ALL the plugs.

Should the gap be set any differently if the plugs are iridium? There seems to be some confusion on this (myself included).

Should the gap be set any differently if the plugs are iridium? There seems to be some confusion on this (myself included).

The iridium plugs from GM do in fact have a different gap from the factory recommended gap for the stock LS1 platinum plugs. And GM specifically states that the new iridium plug for LS1s should not be re-gapped to the original factory recommended gap of .060. They say to leave the iridiums gapped at .040, even in the LS1.

As for non-Delco iridium plugs, I have no idea if they can/should be regapped.

TR55's :judge:

TR55's :judge:
:werd:

TR55's come gapped @ .055" at least the last 5 sets I have had to buy were...

It all depends on power too...the more HP made, the smaller the gap gets..you will see a lot of guys switch to the colder plug, like the TR6 when they go heads/cam/N20/power adder
I currently am experimenting with TR55's gapped to .045".....they were not burning right at stock gap (.055) so I closed it a bit....mind you I am head/cam car...stock I ran reg TR55's out of the box..

I feel the best way to select plugs, is by reading this site, and testing different gaps yourself...removing plugs is not that hard....well except for #8 :)

Stick with the stock AC Delco iridiums.

^^pretty sure stock was NGK?

TR55's come gapped @ .055" at least the last 5 sets I have had to buy were...

It all depends on power too...the more HP made, the smaller the gap gets..you will see a lot of guys switch to the colder plug, like the TR6 when they go heads/cam/N20/power adder
I currently am experimenting with TR55's gapped to .045".....they were not burning right at stock gap (.055) so I closed it a bit....mind you I am head/cam car...stock I ran reg TR55's out of the box..

I feel the best way to select plugs, is by reading this site, and testing different gaps yourself...removing plugs is not that hard....well except for #8 :)
This may be a newb question, but how do you "gap" plugs? As far as I know spark plugs aren't "adjustable", so there's no setting on the actual plug themselves to set a "gap". Do you mean when you install them, or before you install them? How do you gap them? What tools would you use? Thanks for the info!

When you say the TR55's are you talking about the standard or the GP, IX?

This may be a newb question, but how do you "gap" plugs? As far as I know spark plugs aren't "adjustable", so there's no setting on the actual plug themselves to set a "gap". Do you mean when you install them, or before you install them? How do you gap them? What tools would you use? Thanks for the info!

The gap is the distance between the electrode ground strap and the center electrode. You can adjust the gap by either opening or closing this distance with a gapping tool. Then you can check the gap with a feeler gauge.

what does making the gap closer together vs farther apart do? does it cause the car to run lean or rich? also, what's a good gap for tr55's with no cam or nitrous mods. just a few induction mods (lid, ported tb, ssra, etc)?

just got some NGK TR55's/MSD wires in from ws6store and im going to check the gap once i get a little 99 cent gapping tool from autozone tomorrow and ill let yall know what my set is gapped at. from what i have understood anywhere from a .05 to .06 is good on a LS1 and i don't understand why now a .044 would be ok on the same model number plug (3951)...can someone clarify this? Thanks -Karl

i went with NGK tr 55s @.55 with msd wires but my car had 80k on it and wires was looking rough.so far i have no complainst about that plug and wire combo

I hope everyone checks the plug gap before installtion.

I sent NGK an email a few days ago asking if they changed the TR55 (3951) and why the gap is listed different now on their website. Here's their response: "The spark plug has not changed. TR55 will still be preset to .060. The reason for the change in recommended gap setting comes from a change at General Motors with the supplier for O.E. plugs. The new supplier builds the plugs to .044. We have changed our application data to match that of GM. If you have had good success at .060 install TR55 as it comes out of the box." So, someone buys the plugs, they're gapped at .060, look up the gap listed on their chart, see .044. Messed up if you ask me.

I hope everyone checks the plug gap before installtion.
How you do "physically" adjust the gap? Is it on the plug itself? Sorry but I'm having a hard time visualizing gapping. I didn't know spark plugs were adjustable (if they are adjusted on the plug itself).

I sent NGK an email a few days ago asking if they changed the TR55 (3951) and why the gap is listed different now on their website. Here's their response: "The spark plug has not changed. TR55 will still be preset to .060. The reason for the change in recommended gap setting comes from a change at General Motors with the supplier for O.E. plugs. The new supplier builds the plugs to .044. We have changed our application data to match that of GM. If you have had good success at .060 install TR55 as it comes out of the box." So, someone buys the plugs, they're gapped at .060, look up the gap listed on their chart, see .044. Messed up if you ask me.

That's kinda what I figured, however it's odd that they would pick .044 to recommend, since the new Delco iridium plug comes gapped at .040 according to the info I've seen from GM. I have yet to buy the new plug though, so maybe it is .044. But I'm certain that someone had a link posted on here to GM docs stating that the new plug for the LS1 motors was to be gapped at .040.

How you do "physically" adjust the gap? Is it on the plug itself? Sorry but I'm having a hard time visualizing gapping. I didn't know spark plugs were adjustable (if they are adjusted on the plug itself).

To adjust the gap, you have to bend the ground strap closer or further (up or down) from the center electrode.

To adjust the gap, you have to bend the ground strap closer or further (up or down) from the center electrode.
Is the ground strap brittle and/or thin? Where is it located? I'm picturing the metal that "comes over" the tip of a spark plug, and that thing would be hard as hell to bend!

I'm picturing the metal that "comes over" the tip of a spark plug, and that thing would be hard as hell to bend!

That's the ground strap. Beleive it or not, it really isn't hard to bend with a gapping tool. :)

I double checked the email they sent me, does say .044, but maybe a typeo on their part? Notice they didn't specifically say to regap (their unchanged plug) to .044?

NGK's are great plugs but i refuse to use them cause they are made in Japan. Go with AC delco irridiums:)

NGK's are great plugs but i refuse to use them cause they are made in Japan. Go with AC delco irridiums:)

Sweet...couldn't agree more :cheers:

iridiums ix's and superconductors do me just fine

41-985 Spark Plug, Iridium
Gap .040 Do Not Deviate From Preset Gap .040"