Dobeman2000

Going with the factory AC iridium plugs for my 02 c5, wondering if they come "pre-gapped"? Thanks in advance.

GoldenFlame

I'm Pretty sure you leave the gap alone on the iridiums "AC Delco website (and other references) tell you NOT to change the gap from the factory set .040"

dougbfresh

I believe this is true. I think the owners manual has the wrong gap (at least my 01' manual does). I gapped my last plugs to the manual and it ran like do-do. Put them back to what they came out of the box and all was HAPPY again!.

Dobeman2000

Thanks- answers my question

87SAM

A Bulletin came out in 2003:

Information on New Spark Plugs and Gapping #03-06-04-060 - (Oct 24, 2003)
Information on New Spark Plugs and Gapping
2004 Buick Ranier

2002-2004 Cadillac Escalade, Escalade EXT

2003-2004 Cadillac Escalade ESV

2004 Cadillac CTS-V

1997-2004 Chevrolet Corvette

1998-2002 Chevrolet Camaro

1999-2004 Chevrolet Silverado

2000-2004 Chevrolet Suburban, Tahoe

2002-2004 Chevrolet Avalanche

2003-2004 Chevrolet Express, TrailBlazer

1999-2004 GMC Sierra

2000-2004 GMC Yukon, Yukon XL

2001-2004 GMC Yukon Denali, Yukon XL Denali

2002-2004 GMC Sierra Denali

2003-2004 GMC Envoy XL

1998-2002 Pontiac Firebird

2004 Pontiac GTO

2003-2004 Hummer H2

with 4.8L, 5.3L, 5.7L or 6.0L V-8 Engine (VINs V, P, T, Z, G, S, N, U -- RPOs LR4, LM4, LM7, L59, LS1, LS6, LQ9, LQ4)

A new spark plug has been released for use in the above vehicles. The new spark plug has an Iridium tip instead of the current Platinum tip. Due to the different tip design, the gap of the spark plug has also changed. The new spark plug, P/N 12571164 with AC Delco P/N 41-985, is gapped to 1.01mm (0.040 inches) when the spark plug is made. The spark plug gap is set during manufacturing and should not be changed or damage to the spark plug may result. Any new spark plug found to not be properly gapped should not be used.

baxsom

tr55's are set to the same gap right?

hornet7

Better to check the gap before you install the plugs.
I did a tune up on my 98 Coupe with parts from Gene, The parts were good but the gap was off. I found that out the hard way. Did the Seafoam clean, Plug wire replacement, 160DeF Stat, and plugs. After all the new parts were installed. The car ran like crap. Pulled and rechecked the gap and found 6 of the 8 plugs out of tolerance. Re-calibrated the plugs and the car was running like a champ.
Best to check before installing and save a little time.

sccs

so this means i can install these sparks directly with no gapping?

IF not what is the avarage gap for a stock daily driver?

didnt want to open a new topic so i rather made a replay on old one..

Corvette_Ed

Yes, you can install them, but as with any new spark plug you should verify the gap is correct before installing. Accidents happen.

B747VET

My understanding is that you should NOT re-gap the GM Iridium tipped plugs. I believe that it's OK to very carefully/gently check that the gap is correct. However, if the gap seems incorrect, you should return the plugs.

Re-gapping or changing the factory set gap may damage the iridium tip. Also, the iridium plug design requires a departure from the normal gap used on plugs in an LS1 engine.