I just installed new AC Delco plugs in my 2000 Silverado 6.0l earlier. I gapped them at what it said on the sticker at .60. Being an Iridium plug I did it without touching the tip. Now it's come to my knowledge that the sticker is for the platinum style plugs and my iridiums should have stayed where they were. (around .40-.45) The truck runs like a raped ape and definantly gets up and moves faster. Should I be worried and go back and decrease the gap?

 

I've been wondering the same thing just never asked.. gapped mine to .060 as well when they were pre gapped.

If there would be noticeable performance or efficiency increase I would change them back.

 

Below is Information.....On the A/C Delco Iridium Tip Spark Plug and what the gap is for them,

Subject: Information on New Spark Plugs and Gapping #03-06-04-060 - (10/24/2003)

Models: 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)
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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 .....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.

 

.040 is correct.

 

So being gapped to .060 has negative affects or just shouldn't be used because they are specifically gappd at .040?

 

Yeah is it bad to have them gapped at .60 or is it that they just don't want people breaking off the tips?

 

IIRC, the iridium is basically plated onto the plug, so if you try to gap it, the iridium could flake off

 

Plat and iridium do not gap. .040 gap iridum is a thin film plated to plug, when you gap it or even check it with a feeler gauge you can wear it off making the plugs wear very very fast.

copper plug .050-.060 gap

that's what I would do

 

Yes, you do not gap iridium plugs.