Odd Crank Bearing Question

Discussion in 'Small Block Mopar Engine' started by nm9stheham, Nov 9, 2018 at 3:14 PM.

  1. nm9stheham

    nm9stheham Well-Known Member

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    I'm stumped on this one....

    I was perusing the Mahle/Clevite bearing catalog today and ran across 3 different PN's for the non-360 main bearing sets . The descriptive difference is this:
    • MS963V: Engines with 3.305/3.375" main bearing flange OD; listed for 273/318/340
    • MS1344V: engines with 3.460/3.530" main bearing flange OD; listed for 318 only
    • MS540H: There is no mention of main bearing flange OD; listed for 273/318/340
    The individual bearing listings in each set only differed in the #3, thrust bearing, so I assume they are referring to the thrust surface on the crank. And this one bearing set MS1344V is only for the 318 (both LA & Magnum). Soooo.. are there 2 different thrust bearing surface sizes for the 318 and how do you know what came in what? Is the larger for a manual trans crank, or what ??? Is it important?

    One other odd thing: The Mahle/Clevite catalog lists the MS963V as having grooved upper shells and ungrooved lower shells (normal configuration) but one catalog listing says they are grooved upper and lower. Does anyone know a PN for full groove mains?
     
  2. OLDSTYLE

    OLDSTYLE Well-Known Member

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    The thrust OD was changed about 1974
     
  3. OLDSTYLE

    OLDSTYLE Well-Known Member

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    963 and 1344 are both full groove just different thrust OD
     
  4. Garrett Ellison

    Garrett Ellison Amateur driver on public roadway, do not imitate!

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    It has been a while and please correct me if I am wrong... I believe it was '73 or '74 when the 318 picked up a larger counterweight cast crank with an added larger thrust diameter due to the small full float rods being dropped from production and replaced by heavier 360 type rods with press fit pins. I unfortunately lost my copy of Larry Shepherd's How to Hot Rod Small Block Mopars way too many years back to confirm exact year but it should be in the MP engine manual as well.
     
    Last edited: Nov 10, 2018 at 6:05 AM
  5. pishta

    pishta I know I'm right....

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    I got that book and can check when I get home if needed. Thought all 318 cranks were the same... 8-0
     
  6. nm9stheham

    nm9stheham Well-Known Member

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    Please check, Pishta, if you would please.

    The change to the heavier rods might well be a concurrent change, but I am not quite seeing why 32 gram heavier rods would necessitate a change to the thrust bearing surface size..... Maybe it was just a durability improvement... and maybe matches machining on the 360? Since the 273 and 340 had been dropped by that time, that might explain it.

    (And 318's picked up the cast crank when they first came out, and shared that with the later 273's.....IIRC.)
     
  7. pishta

    pishta I know I'm right....

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    found this..."Noticeable differences are (1) Thrust bearing pad on the side of the 1979 crank is bigger than on the 1968.(2) the counter weight part of the crank is much larger on the 1968 crank verses the 1979 crank and the counter weights are not in the same position on both cranks.Cranks fit into the block with no issues "
     
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    • nm9stheham

      nm9stheham Well-Known Member

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      Thanks very much! I see that Crankshaft Supply shows the same 318 crank from '76 though the Magnums. They show the heavier for '71-'91; not sure what to make of that.

      But the main question has been answered... why the PN change.
       
    • pishta

      pishta I know I'm right....

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      Ham, that Shephard book is currently MIA, but I dont remember anything in there about crank compatability, maybe I wasnt looking for it though.
       
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