). You want them gapped between .050" and .060". 
Spark plug gap
Joined: Nov 2001
Posts: 34,632
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From: Schiller Park, ILL Member: #317
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Huge gap! I just bought a set of TR55's and went to gap them, I thought there must be a problem at the factory when all 8 were gapped to .055"! But I guess that is about right huh? I am just an old SBC guy where .030" is norm and .040" is MAX! Those coils must be putting out some serious amperage to jump .055"! don't let one of those things bite you, you'll wake up next week! HAHA. Thanks guys.
I don't remember which GM called for in my 98, but my buddy has an 01 we changed the plugs at the same time. 1 of the Catalyst stickers in the engine bay said .040 and the other said .060. We just gapped them at .050 and called it a day lol.
Joined: Nov 2001
Posts: 34,632
Likes: 2,557
From: Schiller Park, ILL Member: #317
All the TR55s I have ever bought came out of the box gapped at .059". Gaps anywhere from .050 to .060" usually show good results, so .055" seems to be a good middle ground.
.040" is the correct gap for the revised iridium plugs that were issued for the LS1 by GM, in 2003. The original platinum plugs were supposed to be gapped at .060".
.040" is the correct gap for the revised iridium plugs that were issued for the LS1 by GM, in 2003. The original platinum plugs were supposed to be gapped at .060".
TECH Resident
Joined: May 2011
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From: Leander TX
out of the box most of mine were gapped 57? i just put them in like that. and yeah they put out some juice. my friend forgot to plug a boot back onto the plug after he started it and a brain lapse caused him to attempt plugging it back in when the car was running... a "shocking" experience to say the least
