why re-gap spark pluggs?

[tybardy]

I remember some time back reading that people were gapping their spark pluggs to .040 instead of .060.... i saw it again today on a different thread and though i would ask the question... why?

[jmildoc]

Ty I saw this same thing and was wondering if i should go out and check mine. Hope someone gets an answer for both of us.

[Grebbler]

I believe it was because GM changed the spec around 06 or so to .040 to limit misfires and such. New GM Iridium's and such are pre-gapped to .040.

[BOSS]

So that begs the question, to do - or not to do?


BOSS

[tybardy]

i think i shall...

[Sepiroth]

If you're going to do the work of regapping the plugs, IMHO just replace them. That is unless your plugs are new.

[tybardy]

If you're going to do the work of regapping the plugs, IMHO just replace them. That is unless your plugs are new.

my plugs have less then 6k miles on them... i will probably buy new ones and gap those to .040 though... due to recomendation, i use NGK pluggs in my truck which are only $2, so getting 8 more is no worries

[Max]

You'll gain more top end power and a bit of fuel economy. They essentially corrected an error in gapping the plugs too much, I've ran .035 on a bunch of nitrous trucks or forced induction...cooler heat range of course.

[withac]

The NGK's I put in mine came pre gapped and warned not to adjust the gap because the center electrode is so small it could be damaged.

[jmildoc]

NGK's huh I put Autolite Platinum in mine about 3500 miles ago, should I take a couple out and check them?

[tybardy]

The NGK's I put in mine came pre gapped and warned not to adjust the gap because the center electrode is so small it could be damaged.

you could re-gap the plugg without even touching the center electrode, i "checked" each of the NGK's gap before i installed because i didnt trust the pre-gap... many years ago when i had my GMC s-15 i bought some shitty pre-gapped pluggs that turned out to not be pre gapped at all, so not i check.

The act of checking the plug is most likeley what will damage the electrode.. i suppose just use caution

[jmildoc]

alrighty I will have to check a couple out to see. hopefully they are right and I can trust the rest for now, so you like the NGK?

[tybardy]

well i was going to spend a overkill amount of money on new pluggs because my logic is to always spend a little extra to ensure you are getting a quality product... i posted a thread right before i did it and was told by several people, most of which are here in this forum, that the NGK pluggs are JUST FINE and that there was no need to get anything else....

that said, i have had NO problems and ultimatly recomend them to anyone doing new pluggs in their truck

[jmildoc]

i sure wish i would have seen that thread before i spent $7 per plug then wires and full synthetic oil. boy was that a fun trip to the auto parts store

[tybardy]

yea $16 for pluggs all around aint half bad.. i bought 9 just in case i dropped one (which i did)

[Max]

I spent $12 on my tr55s, the basic ones are just fine don't buy into the hype.

[tybardy]

I spent $12 on my tr55s, the basic ones are just fine don't buy into the hype.

:word:

[danimalmax]

What exactly do you mean by re gap? Do I actually pull out a ruler and measure some gap somewhere on the spark plugs?

[tybardy]

What exactly do you mean by re gap? Do I actually pull out a ruler and measure some gap somewhere on the spark plugs?

no you go buy a spark plug gapping tool for a buck or two from your local auto store.... it is a circular tool that will tell you what the gap is and it has a hole at the top of the tool that will allow you to open the gap up. if you need to close the gap up (like in this case) then you can just push it down on any hard flat surface

[Max]

http://www.2carpros.com/how_to/images/spark_plug_gap.gif
http://www.redhillsupply.com/ppp/images/KDT164.jpg
http://wpcontent.answers.com/wikipedia/commons/thumb/b/bf/Spark_plug_gauge.jpg/180px-Spark_plug_gauge.jpg

[JennaBear]

I have the TR55s and are gapped at .035. They were at .040 before the supercharger though. GM changed from .060 to .040, there was an advisory that went out with the change.

[danimalmax]

so how do i know what i should have them gapped at? .035? .040?

[Max]

unless you have a supercharger, turbocharger, or nitrous gap them at .040

[withac]

I put the NGK TR55's in my 5.3. I double checked the gap but all were at .040. As far as pressing the gapping tool against the center electrode to open up a gap I wouldn't do that regardless of it's size. You can slide the outer electrode through the hole with the larger part of the tool turned away from the plug. You can then gently pry down on the tool therebye lifting the outer electrode away from the center one therebye opening the gap.

[tybardy]

I put the NGK TR55's in my 5.3. I double checked the gap but all were at .040. As far as pressing the gapping tool against the center electrode to open up a gap I wouldn't do that regardless of it's size. You can slide the outer electrode through the hole with the larger part of the tool turned away from the plug. You can then gently pry down on the tool therebye lifting the outer electrode away from the center one therebye opening the gap.

thats the proper way of gapping a spark plugg, regardless of what type of plug you are gapping, you should never "wedge" something between the gap to open it up. if you are using the tool correctly, nothing should touch the electrode other the the act of measuring.

[road1will]

I think i may do my plugs today. I know they say they're fine til 100k miles, but i'd be curious to see if i see any change by re-gapping.

[tybardy]

the rear two will give you heart burn, but otherwise an easy project... just be carefull removing the boot as these fuckers are particularly snugg, ive dont pluggs in several cars/trucks, these were the toughest to seperate plugg from wire i ever ran into. Yuo dont want to rip the wire, then your spending $70 on new wires

[withac]

I can NEVER remove all the old wires without ruining one, so I always to wires when I do plugs. I actually don't remember what I used, I think it was Bosch. Some people said they didn't like them but I saw at least a 2mpg increase with the new plugs and wires.

[tybardy]

2mpg increase is HUGE from just pluggs and wires

were your old pluggs all fucked up? did you go with a bigger dia. wire?

[withac]

2mpg increase is HUGE from just pluggs and wires

were your old pluggs all fucked up? did you go with a bigger dia. wire?

Same diameter wire. It had around 93 to 96K miles on it, I don't remember exactly. The old plugs had burned out considerably, I don't remember how much but it was a lot more than .040, big ol' gap.

[tybardy]

i am wanting to buy new pluggs and gap them to .040 more and more now... i just did my pluggs like 5k ago and gapped them at .060... GDI

[jmildoc]

yeah when i did the plugs and wires on my truck right after i bought it i broke two wires.... that was a pain... they hadnt been changed since new,,,, it had 140K on it!!!