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  1. #1
    Member
    Join Date
    Aug 2009
    Location
    Robinson, IL
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    87

    2005 Mercury optimax 225 hp

    I changed my spark plugs on my 05’ opti.
    My serial number is 1B012699
    I put NGK IZFR5G plugs in. These plugs are pre-gapped to .032
    I would guessing with the gap tool I have to try and get the .031 that is called for.
    Will the .001 make a difference?
    Thanks in advance for your help!

  2. Member
    Join Date
    Mar 2018
    Location
    Ashland city tn
    Posts
    171
    #2
    I seriously doubt it. I wouldnt stress it neway

  3. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
    Join Date
    Apr 2008
    Location
    Greenville, SC (US)
    Posts
    94,945
    #3
    Spark plugs are NOT pre-gapped at .032". Need to check them with a wire-gauge, using the "go and no go" method. Do not exert ANY pressure on the firing pin, porcelain, or between the firing pin and the arm.

    Most IZFR5G plugs are right at .027" straight from the box (and yes, that WILL make a difference).

    Proper gap would be .032-.033.

    Moving your thread to the 3L Forum for you.


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