1. Welcome To GMTruckClub.com!

    The #1 Chevy Truck Forum Online
    Online since 2004, we are the #1 Chevy Truck & SUV forum and user community. If you have any questions about your Chevy or GMC Truck, SUV or Crossover, or just want to connect with other GM owners and enthusiasts around the world, you've found the best place on the internet to do that.

    Join Today ~ It's Free
    Registering is Free and Easy! Hope to see you on the forums soon!

Spark plug question. 41-985 vs 49-110

Discussion in 'Maintenance & Upkeep' started by Pikey, Oct 2, 2012.

  1. Pikey

    Pikey Moderator Staff Member 1000 Posts

    I am going to change the plugs in my 2005 yukon xl. The manual calls for a AC 41-985 iridium but the plugs that all of the parts stores list is a AC 41-110 iridium. Does anyone know the difference between the two? I can not find the 985 anywhere. Thank you in advance for sharing your thoughts

    99'HEARTBEAT Moderator Staff Member Platinum Contributor 1000 Posts

    Mike.....there's no difference between the A/C 41-985 and the A/C 41-110 they are the Same Plug........G.M. Changed the Part Number to the A/C 41-110,

    The Below information is from A/C Delco's Online Parts Catalog,
    [TD="align: center"][​IMG][/TD]
    [TD="align: center"][/TD]
    Part Number: 41-110
    Product Notes:
    Iridium-Spark Plug
    .040 GAP

    Per Vehicle: 8; Years: 1999-2005[/TD]

    G.M.C. YUKON XL 1500
    2005 V8-323ci 5.3L F/I Vin T
    2005 V8-325ci 5.3L FLEX/FI Vin Z

    Last edited: Oct 2, 2012
  3. Pikey

    Pikey Moderator Staff Member 1000 Posts

    Thanks Mike. I was hoping that you would respond as it seem like you always have the info when it comes to GM parts!

    99'HEARTBEAT Moderator Staff Member Platinum Contributor 1000 Posts

    Glad to help Mike, and regarding the Gap on the New Plugs, below is from a G.M. Service Bulletin,


    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, A/C Delco Iridium Part Number 41-110, 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 to the Gap required with the Platinum plug, or Damage to the Spark Plug may result.

  5. Pikey

    Pikey Moderator Staff Member 1000 Posts

    I pulled out 3 plugs a few minutes ago. They came out easily. They look new and the gap is .038". So, looks like I have to start investigating other causes of my sudden MPG decrease. Thanks again for the info
  6. RayVoy

    RayVoy Active Member 1000 Posts

    I would look at the front O2 sensor(s)

Share This Page