Small block crank

Small Block Mopar Engine

  1. Sterling

    Sterling Well-Known Member

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    Anyone running a crank turned .040 under on the rod journals? I picked up a 1967 340 short block that was built to race, started and ran a little but never raced. It had a set of W-2 heads on it that leaked. So I got the short block cheap. I was comparing the steel crank to another one I have here and found out the rod journals are turned .040 under. I have heard of cranks turned down to 2.00 , but not with stock rods.
     
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    • MOPAROFFICIAL

      MOPAROFFICIAL FABO Gold Member FABO Gold Member

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      What was the old saying....Thicker the bearing ...the less heat in the oil/or cooler running journal.... I cant remember now.but think along those lines.
      I guess I'd just run a babbitt/harder bearing if I were worried about the bearing thickness...assuming that's the concern to begin with. Jmo
       
    • pittsburghracer

      pittsburghracer FABO Gold Member FABO Gold Member

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      I had a stock 360 crank cut down .030 last year but I had them wait till I had bearings. I found a set of fully grooved bearings on eBay so they cut away so I would check availability before doing anything
       
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      • Sterling

        Sterling Well-Known Member

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        This engine was together and running before I got it. The bearings look brand new, and I am going to check the clearances. If the clearances are good, I was going to reuse them 20220114_121834.jpg
         
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        • toolmanmike

          toolmanmike Moderator Staff Member FABO Gold Member

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          I use new bearings each time. They go through a torque cycle a time or two and loose their crush. (from what I have heard.)
           
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          • Sterling

            Sterling Well-Known Member

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            I always do too, except for this engine, that I don't want to stick any money into it. If I don't like the clearance, I will put another crank in it, with new bearings 20220114_122235.jpg
             
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            • jazak5

              jazak5 Well-Known Member

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              baa085515c83f9b?pid=1.7&rurl=https%3a%2f%2fthumbs.gfycat.com%2fPlasticBeneficialArcticseal-small.gif
              sounds like a stroker !!
               
            • doug 371

              doug 371 Well-Known Member

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              check the stroke...maybe it has been offset ground...
               
            • Sterling

              Sterling Well-Known Member

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              I will check the stroke, but looking at the piston and rods, I don't think it is offset ground
               
            • perfacar

              perfacar Well-Known Member

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              undersize bearings have same thickness of bearing material, the steel backing is where the added thickness is made. smaller dia , has less bearing speed and friction. makes more power.
               
            • Max1196

              Max1196 Well-Known Member

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              Personally, I think your safe. If this works at .200 off set and .300 off set, .040 is good to go.
              Crank Shops for Offset Crank Grinding? | For A Bodies Only Mopar Forum
               
            • polyjohn

              polyjohn Well-Known Member

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              I didn’ Know you could get 0.040 under S/B bearings?

              The smaller the bearing surface the less friction you have.
              Mopar journals are pretty big compared to modern engines.

              Big blocks run the Chevy rods now with 2.200 rod journals.
              Not sure what is available in the S/B world?
               
            • CNC-Dude

              CNC-Dude Well-Known Member

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              Big block Chevy Pro Stock engines have been using Honda rod journal sizes for close to 20 years now. Their Ford and Dodge counterparts have as well. It's real common for most small blocks(Chevy, Dodge and Ford)to use Honda journals these days also.
               
              Last edited: Jan 16, 2022 at 9:50 AM
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