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  1. #1
    Sr. Apprentice
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    Sep 2013
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    Angleton TEXAS
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    Default Spark plug question

    My 99 Sierra 5.3 when to removed the original spark plugsAnyone at 250k, I took an original to O'Rielly's and got the replacements. Anyway the spec sticker under the hood said spark plug gap at .60, the replacements are pregapped at .40.... That's what their computer said.... I just stuck them in. Should I have re gapped them to .60 or was it fine to leave them at .40..... Runs fine

  2. #2

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    Quote Originally Posted by Jeff Dodson View Post
    My 99 Sierra 5.3 when to removed the original spark plugsAnyone at 250k, I took an original to O'Rielly's and got the replacements. Anyway the spec sticker under the hood said spark plug gap at .60, the replacements are pregapped at .40.... That's what their computer said.... I just stuck them in. Should I have re gapped them to .60 or was it fine to leave them at .40..... Runs fine
    gap them at .60 if that is what the hood says to do. "Runs fine" should become "runs great"
    Chuckie!!!


  3. #3

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    Quote Originally Posted by Jeff Dodson View Post
    My 99 Sierra 5.3 when to removed the original spark plugsAnyone at 250k, I took an original to O'Rielly's and got the replacements. Anyway the spec sticker under the hood said spark plug gap at .60, the replacements are pregapped at .40.... That's what their computer said.... I just stuck them in. Should I have re gapped them to .60 or was it fine to leave them at .40..... Runs fine

    Jeff if you bought A/C Delco Iridium Tip Spark Plugs......do not attempted to Re-Gap them,

    Here's a GM Service Bulletin that goes into detail Regarding Gaping of the Iridium Plugs,......if you bought Platinum Plugs, then as the sticker under the hood said Spark Plug Gap at 0.60....


    --------------------------------------------------------------------------------
    Service Information 2000 Chevrolet Chevy K Silverado - 4WD | Sierra, Silverado, Suburban, Tahoe, Yukon (VIN C/K) Service Manual | Document ID: 1903277
    #03-06-04-060A: Information on New Spark Plugs and Gaping - (Feb 12, 2007)



    Subject: Information on New Spark Plugs and Gaping


    Models: 2004 Buick Rainier

    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)


    Attention: Please disregard the Set Gap Per Vehicle Specification statement on the side of an ACDelco« Iridium Spark Plug Box. The statement will be removed from the boxes in the future.

    • 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 Gaped to 1.01 mm (0.040 in) when the Spark Plug is Made.


    ***Notice: 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 Gaped Should Not Be Used.



    EDIT:....I would also mention, that the Spark Plug Fastener Tightening Spec's. are 11 lb ft and also make sure to use some.....Anti-Seize Compound on your Spark Plugs, is particularly advisable with Engine Head's made of Aluminum, and use Dielectric Grease, Use your finger to spread the Dielectric Grease around the Ceramic Portion of the Spark Plug. This will help maintain a dry environment for the Spark Plug to Wire connection. The Grease will also make Re-Installation of the Plug Wires easier.


    EDIT:.....GM has Changed the Part Number for the Iridium Tip Spark Plugs, the New Part Number is 41-110
    Last edited by 99'HEARTBEAT; 01-22-2014 at 10:44 AM. Reason: Posted, New Part Number for the Spark Plug

    MIKE


    99"SILVERADO
    5.3 l 3.73 l G80
    BLACK BEAR CUSTOM TUNE
    SNUGTOP l COLORMATCH l KATZKIN










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  5. #4

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    I didn't think about asking what kind of tip they have... *palm to forehead*

  6. #5
    Sr. Apprentice
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    Alliance,Ohio
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    Default

    Is the gap realy .600 or is it .060??????????????
    1998 1500 w/t short bed 4.3

  7. #6
    Sr. Apprentice
    Join Date
    Sep 2013
    Location
    Angleton TEXAS
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    Default

    Well being that .600 is over half an inch, pretty sure I meant .060.... But thanks, it is the iridium plugs, that is what O'Rielly's books called for. Thanks again

  8. #7

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    Quote Originally Posted by fugitive View Post
    Is the gap realy .600 or is it .060??????????????
    The Gap on the Platinum Plugs is....0.60


  9. #8
    Legend

    Join Date
    Sep 2010
    Location
    everett, massachusetts
    Posts
    1,487

    Default

    the gap was changed and so was the plug from OEM factory install.

    the ac delco irridium plugs should be used. this engine like my 2000 is plug picky. the use of this plug has shown me a good improvement when the engine is cold.

    also irridium is a material that takes the high combustion chamber temps with no problem . plat plugs do get damaged from the heat in these engines. I had the plat tips fall off and so did others. these plugs will last for 100,000 miles.

    if you see the gap is not .040 then you do not adjust them. the plug is defective , get another plug. I would check at store all plugs have the correct gap by looking.. using a tool these can be damaged very easy.
    Last edited by j cat; 12-11-2013 at 07:45 AM. Reason: clarify gap

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  11. #9
    Sr. Apprentice
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    Sep 2013
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    Angleton TEXAS
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    Default

    It's the iridium plugs I have. The direct replacement and they are factory gapped at .040

  12. #10

    Default

    Quote Originally Posted by Jeff Dodson View Post
    It's the iridium plugs I have. The direct replacement and they are factory gapped at .040
    As our trucks are both 99"s.....they came from the Factory with Platinum Plugs, that were Gaped at.....0.60.....and GM is now Installing at the Factory, the Iridium Plugs with the Gap at 0.40


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