NGK TR55IX

[sagent]

I just picked up a set of NGK TR55IX plugs for my 03 Yukon and checking the gaps on the plugs it appears they are a hair above

.050". The NGK website lists the gap for the plug in that application .044" and the owners manual says .060"

 

What should the actual gap be for these plugs and are these a decent replacement for the originals? I thought I read somewhere you cannot re-gap a platinum / iridium plug.

 

Appears there is a error with search function right now is why I posted this

 

Thanks

[svensk]

Do not readjust the iridiums. They are factory gapped and you could damage them by regapping. However if all your plugs are gapped differently then take them back and get new ones with the same.

[sonjaab]

SAG..............Ignore that "they are pre gapped at the factory" bull !!!!!!!!!!!!

NO sparkplug I have ever bought OR installed no matter what brand was

EVER correctly pre-gapped from the mfr.

 

As you can see for yourself GM calls for .060 yet the plus you have are

open to .050 and they call for .044........................

 

It don't take a genius to figure it out!

Me??????? I would return those $pendy plugs and get a set of AC Delco

plugs and gap them at .060 or whatever the sticker under the hood

recommends...................geo

[svensk]

GM put a bullitin out stating that iridiums, *NOT* the platinums are to be gapped at .044

 

plats are still .06

[sonjaab]

WEEEEELLLLLLLLLL THEN !!!!!!!!!!!!!

Just slap them in AS IS and thats it !

[sagent]

Thanks for all the replies. I called NGK tech support to clarify as their website lists the gap to be .044" . They told me the plugs can be re-gapped but you run the risk of the having the plugs electrodes of center. They told me to loeaves them as is out of the box and install with the gap at about .054". I also read on denalitrucks.com that closing the gap to .040" equates to about a 10 hp gain vs. the stock setting of .060".

 

I ended up returning the NGKs and buying a set of 41-985 AC Delcos at the dealer which are preset to .040" as per the TSB GM put out in october '03.

[svensk]

Yeah, closing the gap makes the engine burn hotter.

[dewfpo]

Closing the spark plug gap has the effect of advancing the timing. When timing is advanced, the fuel is burned earlier in the rotational cycle of the crankshaft, so more of the heat is generated in the engine and stays in the engine. Smaller gap requires less time for the coils to build up enough voltage to jump the gap. Wider gaps are needed with leaner mixtures to ensure a good burn. Smaller gaps are better for high rpm running.

 

DEWFPO

[dewfpo]

GM put a bullitin out stating that iridiums, *NOT* the platinums are to be gapped at .044

 

plats are still .06

 

 

That's becasuse of the different conductivity of the two metals. Iridiums at .044" produce approx. the same spark at approx. the same time as platinums at .060". It takes different voltages/coil load rates to fire those plugs and GM wants the engines to perform the same and produce the same amount of emissions for the onboard systems to handle.

 

DEWFPO