Main and big end bearing clearances | FerrariChat

Main and big end bearing clearances

Discussion in '365 GT4 2+2/400/412' started by 365mat, Nov 3, 2020.

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  1. 365mat

    365mat Rookie

    Nov 3, 2020
    5
    Full Name:
    Mathew Reader
    #1 365mat, Nov 3, 2020
    Hi guys,

    Is there any original engine tolerances / wear limits available for the 365 GT 2+2 V12 engine?

    I have a 'rebuilt' engine I am working on which has big end bearing clearances ranging from 0.90mm to 0.110mm which seems way too high.

    The crank journals measure 43.610mm, is 44mm standard size?
     
  2. raemin

    raemin Formula 3

    Jan 16, 2007
    1,881
    Lyon (FR)
    Full Name:
    R. Emin
    #2 raemin, Nov 3, 2020
    Is this 0.90mm~0.110mm or 0.090~0.110mm ?

    The workshop manual for the 365 is the same as the 365 GTC4 (was not updated by Ferrari). I do not have this manual, here is an abstract of the 400 workshop manual section B12 (available on Erwin's blog). the crankshaft sizes of the 400 are different obviously, but the tolerances should be roughly the same.

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    I could not find bearings suitable for my crankshaft as the first oversize did not compensate for the wear (damage) of my crankshaft. Having these custom made to the proper size did cost me a lot more (x4) than the "off-the-shelves" bearings as sold by superformance. Maybe the rebuilder bought what was available considering this was within the 0.15 wear limit ? This would make a 10% saving on the total cost of an engine rebuild.
     
  3. 365mat

    365mat Rookie

    Nov 3, 2020
    5
    Full Name:
    Mathew Reader
    #3 365mat, Nov 4, 2020
    Yes sorry 0.090mm-0.110mm.

    Thank you for the info, I have downloaded that from Erwin's.

    It currently has STD bearings fitted, with 1st under bearings it would be closer to original clearances but still not perfect.
     

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