New Plugs

AirForceAngler · February 22, 2006

Well, at 96,xxx miles, I decided to put new plugs in my 2000 Silverado 5.3. I went to O'Reilly's because they usually have the better parts and people in my area. Well, I went for the Iridium AC Delco plugs at $6 a piece. Their computer said to not adjust the factory settings on the plugs. According to the owners manual the gap is suppose to be .060" but the new plugs were .040". I installed them as they came out of the box and the truck felt like it lost power. It ran and idled smooth, but just felt weak. I called to double check the part number for the plugs and it said it was correct and according to their computer that part number should be gapped at .040". Well I gapped them to .060" and reinstalled them and it runs a lot better now. Don't feel much difference between them and the old plugs, but they do run better at the .060" gap.

Anyone else run into this? By the way, I installed the Borg/Warner wires also.

jwhjr · February 23, 2006

Well, at 96,xxx miles, I decided to put new plugs in my 2000 Silverado 5.3. I went to O'Reilly's because they usually have the better parts and people in my area. Well, I went for the Iridium AC Delco plugs at $6 a piece. Their computer said to not adjust the factory settings on the plugs. According to the owners manual the gap is suppose to be .060" but the new plugs were .040". I installed them as they came out of the box and the truck felt like it lost power. It ran and idled smooth, but just felt weak. I called to double check the part number for the plugs and it said it was correct and according to their computer that part number should be gapped at .040". Well I gapped them to .060" and reinstalled them and it runs a lot better now. Don't feel much difference between them and the old plugs, but they do run better at the .060" gap.

Anyone else run into this? By the way, I installed the Borg/Warner wires also.

<{POST_SNAPBACK}>

Looks like the .040" is correct:

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.