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Clevite Bearing Decoding

Discussion in 'Intermediate CJ-5/6/7/8' started by FlatlanderCJ5, Jun 28, 2022.

  1. Jun 28, 2022
    FlatlanderCJ5

    FlatlanderCJ5 Member

    Wichita, KS
    Joined:
    Jan 2, 2022
    Messages:
    151
    Is anyone good at decoding the part numbers on Clevite bearings?
    Me: 1973 CJ5, 360 V8.
    I currently have my engine on the stand, upside down, oil pan pulled. I am checking the main bearings. My question first, and then I will give my clearance readings.
    Can I just replace main bearings with a standard set and continue on? I want to get the jeep reassembled and running and then have the engine rebuilt at a later date if needed. I have only had it running for a few minutes after I bought and it and then I tore the entire jeep down due to every thing needed to be rebuilt. Not sure how many miles are on the engine but I'm guessing a lot. I did the plastigauge check and came up with some interesting readings. The bearings looked a little scuffed, but not too awful. The thrust bearing #3 was worn through to the copper. Anyway here's some numbers, see what you can make of it. Some of the numbers are self explanatory, some I am guessing at what they mean. Thanks in advance for decoding. The bearing number are how they appear on the bearing cap, 1-5. Do these numbers look like they are original standard size?


    Bearing 1: Clevite 66, 9 79, MB2579P, gauged out to 0.002+, scuffed. (Front main)
    Bearing 2: Same as #1. Gauged out to 0.003, scuffed.
    Bearing 3: Clevite 77, 1 79, MB2578P, gauged out to 0.004+, worn through.
    Bearing 4: Same as #1, gauged out to 0.003, scuffed.
    Bearing 5: Clevite 66, 1 80, MB2579P, gauged out to 0.002, slight scuff. (Rear main)
     
  2. Jun 28, 2022
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
    Joined:
    Sep 23, 2002
    Messages:
    12,529
    Main and rod bearings are stamped with the size if over stock size. Would be stamped .010”, .020”, etc. Whether stock bearings will work for you depends on the condition of the crankshaft journals, not the bearings.
     
    Bondo likes this.
  3. Jun 29, 2022
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,596
    The TSM has a list of factory oversized bearings. The factory would use specially sized bearings if needed.

    You should look in the TSM for the year of origin of that engine, not the year of your Jeep. You understand that the 360 was never offered in a CJ.

    I would invest in the needed micrometers and measure the journals. https://www.amazon.com/gp/product/B0045VKF5K/ Typically a cast iron crank (like this) wears along with the bearings, and replacing the bearings will not restore it to original clearance. Might be ok, but I would not assume anything and would measure.

    You can get a "crank kit" at your local automotive machine shop that comes with properly sized bearings. Exchange your crank and get everything you need. I would still check with Plastigage, at a minimum.
     
    Last edited: Jun 29, 2022
  4. Jun 29, 2022
    FlatlanderCJ5

    FlatlanderCJ5 Member

    Wichita, KS
    Joined:
    Jan 2, 2022
    Messages:
    151
    Thanks for the info.
     
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