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400GT WSM tightening torque

Discussion in 'LamborghiniChat.com' started by GaryFB, Feb 12, 2021.

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  1. GaryFB

    GaryFB Rookie

    Jan 24, 2010
    3
    #1 GaryFB, Feb 12, 2021
    I am in the process of assembling a Lamborghini 400GT engine and I am questioning the tightening torque for many of the fasteners. Is there a Work Shop Manual I can get that has clearances, tolerances, and tightening torques?
    For example, the M10x1.00 cylinder head nuts have a torque of 3.0mKg, (21 ft-lbs). That seems very low?
    The main bearing cap nuts, M12x1.50, 3.5mKg (25 ft-lbs). Again, seems very very low. Can this be correct?

    Your help would be greatly appreciated.
     
  2. EarlyCat

    EarlyCat Moderator
    Moderator

    Mar 9, 2005
    9,979
    Shot gun shack n another prt of the World GS KW KY
    #2 EarlyCat, Feb 12, 2021
  3. Lel

    Lel Formula Junior

    Oct 11, 2007
    295
    #3 Lel, Feb 13, 2021

    Not correct. Should be:

    Main bearing studs: 8 mm 1,8 kgm

    12 mm 3,5 kgm

    Main bearing nuts: 8 mm 2,8 kgm

    12 mm 9,0 kgm


    Cylinder head stud: 10 mm 2,8 kgm

    Cylinder head nut: 10 mm 8,6 kgm

    Connecting rod: 6,0 kgm


    L-E
     
    EarlyCat likes this.
  4. GaryFB

    GaryFB Rookie

    Jan 24, 2010
    3
    #4 GaryFB, Feb 13, 2021
    LE,
    Thank you for the tightening torque, those numbers sound correct for the thread size. That’s very valuable information, where did you find it?
    Now that I have the correct torque specs, I torqued the main cap nuts and measured the main bearing clearances, and I have too much clearance (0.0045”, 0.1143mm). The crankshaft measures (2.4790” , 62.966mm).
    I am assuming the crank journal was 63.000mm new, but I don’t know the acceptable tolerance.
    Do you think i got a bad set of main bearings?

    thanks for your help.
     
  5. Chadbourn Bolles

    Chadbourn Bolles Formula Junior
    BANNED

    Aug 5, 2005
    820
    Leesville, SC USA
    Full Name:
    Chadbourn Bolles
    #5 Chadbourn Bolles, Feb 13, 2021
    Gary,, Crank specs for 400GT engine same as Espada, Jarama, LP400, LP400S 350GT, Islero. Torque specs also same.
    MAKE SURE YOU DO NOT TORQUE THE STUDS TO THOSE NUMBERS THAT WERE GIVEN.

    Torque specs on the STUDS are no where near those numbers Like main bearing 12 mm stud around 24 lb, Same for the head studs.

    If you will go to LAMBORGHINIONLY.COM, you can find all that information there. I posted it for FREE for anyone needing it.
     
  6. Lel

    Lel Formula Junior

    Oct 11, 2007
    295
    #6 Lel, Feb 13, 2021

    Original it measures 62.979 mm and the clearence should be min 0,04 mm. 0,1143 may be a little to much?

    L-E
     

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