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  1. #1
    Member
    Join Date
    Apr 2013
    Location
    Jacksonville, Florida
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    431

    Prop nut question

    How tight do you guys tighten your prop nut? My manual says 55 ft lbs. but that sure doesn’t seem very tight. I asked my mechanic and he said to be sure and not over tighten as it can cause issues with the prop shaft. Also, when changing props and using a block of wood, do you guys ever worry about bending the one blade that the block of wood rests against when tightening? Seems like a ton of pressure on just that one blade. Thanks.
    2021 Bullet SDC
    Mercury 300R

  2. Member
    Join Date
    Mar 2008
    Location
    KINGSPORT, TN
    Posts
    3,068
    #2
    Good questions. I have always wondered the same thing. I personally tighten my prop nut maybe a little tighter that what is suggested. But I have really never put a measure on it.
    Last edited by BULLET FAN; 05-08-2023 at 10:05 AM.
    2005 21XD W/ 2005 MERC 250XS BULLET TOTAL PERFORMANCE BOAT!!

  3. Member
    Join Date
    Aug 2004
    Location
    Gonzales, LA
    Posts
    2,436
    #3
    There is a bellville (concaved) washer the flattens @ 55 ft/lbs & keeps pressure on the nylcock nut to keep it from backing off. I tighten mine to 60 ft/lbs & never had an issue. I dont think you will bend a prop blade against a piece of wood & 55 ft/lbs.
    ‘17 Bullet 21 SDC ‘20 Merc 300R 1.60 SM 1E081012

  4. Member
    Join Date
    Jan 2008
    Location
    Angier, NC
    Posts
    852
    #4
    I tighten 60# on all blades. Ive been told if just tighten to one blade the square bores may not seat square and cause a slight vibration and actually loosen slightly after you run the prop.
    21 XRS
    Garmin, LVS 34, lithium Pro, SeaClear
    8ft PP, Move and Charge

  5. Member
    Join Date
    Apr 2013
    Location
    Jacksonville, Florida
    Posts
    431
    #5
    Thank you guys for the responses. I need to make sure my concave washer is on in the correct sequence.
    2021 Bullet SDC
    Mercury 300R