Spark Plug Torque

Discussion in 'Electrical' started by Taildraggerdave, Apr 18, 2013.

  1. Taildraggerdave

    Taildraggerdave Active Member


    I just changed my spark plugs with new in accordance with the 25K service on my '09 Ultra Classic. The plugs are original and have never been out of the engine before. They looked pretty good as well. Installed HD 6R12 plugs.

    I have a factory service manual and it says to put Loctite anti seize on the plug threads and torque plugs to 12 -18 foot pounds. 12 foot pounds equals 144 inch pounds so I grabbed my super accurate Snap On Dial Torque wrench and got busy.

    I got scared about 125 inch pounds and stopped. I realize the crush washer is compressing but I swear it started to feel light and the needle stopped climbing so I stopped. 18 foot pounds is 215 inch pounds and based on how it felt, it doesn't seem like it would get there.

    I've torqued thousands of bolts (really) and you can always tell if the threads are gonna fail when it starts to get easier while in mid torque.
    Sure you can stop there but chances are a helicoil or some type of insert is in your future.

    When I took the old plugs out they were only tight for maybe an 1/8th of turn then I took them out the rest of the way by hand. Pretty sure I'm cool with the new plugs but just thought I'd toss this out for discussion. I'm probably being paranoid but I do not want to have to do any thread repair to the heads. Bike starts and runs fine.

    Take care,
  2. bc45

    bc45 Active Member

    The first time I changed plugs in my 09 FLHTCU I also got that same feeling,
    I removed and checked the threads they were OK. I reinstalled to what felt tight enough. have been in for for 13K and have not come loose.
  3. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

    I have never used a torque wrench when doing spark plugs my dad taught me how to do plugs by feel many years ago with the watch words of do not over tighten them
    I have met people who in the past managed to over tighten the plugs and strip the threads the first who asked me for help with a stripped threads paid for the kit to replace the threads i am sure it is by recoil but very similar to helicoil the kit has been used a few times now and is still part of my tool collection

  4. Bodeen

    Bodeen Well-Known Member Staff Member Moderator Contributor

    I am with Brian, tighten without TW and just get them into the crush washer.

    Dad always said "tight is tight and too tight is broke".
  5. Taildraggerdave

    Taildraggerdave Active Member

    Thanks for the replies.
    I've always snugged them myself. But thought hey, let's torque 'em this time....
    I'll probably go back to the old way from now on.

    Take care,
  6. gator508

    gator508 Well-Known Member

    Very wise words
  7. Sunnysideup

    Sunnysideup Junior Member

    I had a plug fall out of the head on a 74 Chevy Malibu back when I was a kid. Thank goodness it didn't fire out during a compression stroke or it would have shot out like a bullet. Dad was riding with me at the time and I was sure glad I was not responsible for the plug being left loose. He would have chewed me bigtime. I can only assume the plug was just started hand tight.
  8. Taildraggerdave

    Taildraggerdave Active Member

    I'm gonna keep an eye on the plugs for the next few thousand miles.
    I'll make it part of the pre ride check. Should be cool....
    Or keep my left knee out of the way :D

    Take care,
  9. HDSickness

    HDSickness Banned

    I only tighten snuggly.
    Never torque.
    So the book says change pugs every 25,000 miles?
    I change mine every 5-10 k, they are cheap and easy.
  10. Davidw2415

    Davidw2415 Senior Member

    I've always tightened plugs as tight as I could with fingers the a 1/4 turn with wrench.