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    ACL bearing crank clearances for SR20 rebuild


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    9 replies to this topic

    #1 Ungodlyfreak

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    Posted 24 June 2016 - 03:54 PM

    Hey guys, as most of you probably know I'm rebuilding my SR after spinning a big end. I picked up a second hand crank in good condition and some ACL main and rod bearings with the rest of the rebuild gear. I know the factory nissan bearings are graded with a difference of about 0.003mm between bearing grades. The ACL bearings are only sold in a single standard size. So what's the go with that? Do I need my crank machined for these bearings? I assume i should be referring to the factory bearing-crank clearnace tolerances. Should I just put the ACL bearings in, measure it all up and hope it lands in spec? I had planned to get my crank polished before assembly, but was wondering if i might need to get it machined at all.
    I'm not going to be touching any of it till I can figure out exactly what I need to do.
    Cheers.


    Israel
    Perth
    S15


    #2 Munt.

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    Posted 24 June 2016 - 04:37 PM

    Theres plenty of threads, especially about rb's,that have the info you want. Youll find the nissan grading is so fine that it doesnt matter that the acl bearings are one size only, the clearances will still be in oem spec. People do machine cranks to get specific tolerances but it takes off any coating the crank may have, not sure if sr has any. You should be able to calculate your clearances from the markings on the crank/block and compare to the acl

    Edited by Munt., 24 June 2016 - 04:39 PM.

    Name: Matt
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    [18:22] what happen if munt wants to do a burnout before the oil warms up?
    [18:23] <@kev> the world divides by zero and we all perish in a worm hole


    #3 Ungodlyfreak

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    Posted 24 June 2016 - 05:42 PM

    Just checked the ACL website, turns out they have specs there which answer my questions haha.
    Now I just need to find a micrometer that measures to 3 decimal places and a bore gauge. ...anyone?


    Israel
    Perth
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    #4 Munt.

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    Posted 24 June 2016 - 06:41 PM

    You don't really need to measure because you can cross reference the stampings on the crank and block with the table in the manual, but i would double check anyway. If you don't have a manual i suggest you download one and read through it first because it literally tells you how to do everything!

    bearingcode5.jpg


    Edited by Munt., 24 June 2016 - 06:50 PM.

    Name: Matt
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    [18:22] what happen if munt wants to do a burnout before the oil warms up?
    [18:23] <@kev> the world divides by zero and we all perish in a worm hole


    #5 Ungodlyfreak

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    Posted 24 June 2016 - 10:17 PM

    Yeah, I have a manual, I was just a bit confused by the grading of the nissan bearings vs the standard sizing of the acl bearings.
    Is plastigauge actually a reliable measure for oil clearances? Or should I be chasing down the proper tools? The micrometer i have only measures to 0.01mm and I don't have a bore gauge. My uncle may have one though, so there's hope.


    Israel
    Perth
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    #6 SR14WA

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    Posted 25 June 2016 - 08:57 AM

    I just banged in the acl bearings when I rebuilt my motor and it worked out fine #yolo. All though you really don't know this history of the crank you have.

    #7 Ungodlyfreak

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    Posted 25 June 2016 - 10:34 AM

    I know i could just yolo it and it would probably work out fine. However, given the time and money spent so far, i don't want to rely on probably. And I'll murder someone if this engine fails again. In my opinion: do it once, do it right.
    Plus i want to learn all the technical details of engine building too. It will be helpful to know how to measure things properly and understand clearances for future builds.
    The crank actually came out of an s13 called [workhack] I think it was.

    Edited by Ungodlyfreak, 25 June 2016 - 10:34 AM.

    Israel
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    #8 SR14WA

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    Posted 25 June 2016 - 03:35 PM

    Yep that's fair enough, my build was very different to yours so I can understand why your doing what your doing :)

     

    That build thread/car is on here somewhere



    #9 StevenS13

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    Posted 11 July 2016 - 08:59 PM

    At work we use plastigauge to measure the oil clearances, on diesel engines and everything seems to work out fine, they get thousands of hours from high torque applications, and i actually don't know what else you would use to measure it?


    Steve
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    #10 Surrufus

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    Posted 14 July 2016 - 07:50 AM

    I've never seen a micrometer measure to 1/1000 ( 0.001 ) of a mm ( which is silly given the name of the tool ).

    Plastigauge is indeed a legit method.

     

    I'm not sure how you would measure microns accurately ( which is exactly what you want ).

     

    EDIT apparently a micrometer was originally designed to measure in 1/1000s of an inch!

     

    EDIT EDIT they do make micrometers with a "vernier" scale to measure to 1/1000 of a mm ( 0.001mm )!!!


    Edited by Surrufus, 14 July 2016 - 07:56 AM.

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