What is a "steel offset ground crank with Chevy Journals" ?

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  1. Mike Gaines

    Mike Gaines Well-Known Member

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    I Have a buddy looking to buy a motor.
    The motor is a low deck 469" motor ( 4.375 Bore / 3.900 Bore ) with very excellent, high dollar parts such as Manley Steel Rods, T&D Rockers, Jesel Belt drive, Comp Roller cam, Milodon dual line oiling system, etc, etc.
    The owner of the motor truly forgets the details on the crank...and I believe he is honest about that.
    His "build sheet" from the engine builder states the crank as a "steel offset ground crank with Chevrolet Journals"
    Is this just stock steel crank that has been modified (re-ground with an offset ) to make a 469 Motor or could it be an aftermarket crank ?
    If it is a stock steel crank that has been offset ground to give it a larger stroke does that make the crank a weak part of the engine build ????

    Info please...thanks
     
    Last edited: May 3, 2020
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    • Sahara

      Sahara FBBO Gold Member FBBO Gold Member

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      I read an article years ago in one of the MOPAR mags where you take a 383-400 block and put a 440 crank in it, ground to take big block chev rods to make 470 cubes. Need custom pistons. Was all the rage for a while. Supposed to be a torque monster. Must be more info out on Google somewhere, I can be the only guy that remembers this.
       
    • MoparLeo

      MoparLeo NRA PATRON LEVEL LIFE MEMBER FBBO Gold Member

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      That is different. This one says "offset ground" That means the connecting rod journals are ground off center to increase the stroke and they had to go to a smaller journal to do it when they ground it. It is cheaper to regrind a crankshaft than to buy a new aftermarket crank that was made with a longer stroke to begin with. Just cheaper money. May or may not be fine ?? It is a modified part.
       
    • Sahara

      Sahara FBBO Gold Member FBBO Gold Member

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      Yeah, ummm, that’s what I was talking about. Wouldn’t be any reason to to grind the crank to the smaller chev rod size otherwise.
       
    • Sahara

      Sahara FBBO Gold Member FBBO Gold Member

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      7FE155D8-0326-4731-9696-86C2BC23DF41.png Found this in less then thirty seconds. Clearly says offset ground.
       
    • 1 Wild R/T

      1 Wild R/T FBBO Gold Member FBBO Gold Member

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      Yup, use to be the hot ticket... Now you can buy a crank made for the combo but in the 90's you offset ground a steel crank.... not a problem..
       
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      • Kern Dog

        Kern Dog FBBO Gold Member FBBO Gold Member

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        The Chevrolet rod journals were a smaller 2.2" size. Smaller bearing, less drag.
         
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        • 1 Wild R/T

          1 Wild R/T FBBO Gold Member FBBO Gold Member

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          Smaller bearing less drag is nice but the real advantage is taking all the metal off the bottom makes the stroke longer... 3.9". stroke
           
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          • 33 IMP

            33 IMP Well-Known Member

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            Yes, it is a stock steel crank. It is not ground on the center of the rod journals, it is ground only on one side. That increases the stroke. By using chevrolet journals, you gain physical room in the crankcase because the chevy rod big end (outside dimensions) is smaller than a mopar. It also gives a much bigger selection of aftermarket rods. But yes, more metal is removed from the crank on one side than would be removed with a simple regrind, so yes, the crank must be weaker than stock.
             
          • Kern Dog

            Kern Dog FBBO Gold Member FBBO Gold Member

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            Okay but they were plenty strong to begin with. Maybe not the first choice for a turbo or blower motor but...
             
          • mopar 3 B

            mopar 3 B Well-Known Member

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            Had one years ago that was cut on one side and built up on the other. Used standard Chrysler rods.
             
          • Lefty71

            Lefty71 FBBO Gold Member FBBO Gold Member

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            Yes.... thats how you make a 474 too. Eagle makes that crank still. And Eagle makes those rods to fit it. BBC sized big rod ends
             
          • Curiousyellow71

            Curiousyellow71 Well-Known Member

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            I would not be worried about the rod journals. A rod offset ground with a 2.2 pin is not likely to weaken it...especially if they do a bigger fillet radius. I would think a rod journal cracking would be unusual compared to a main. We've cracked a main journal before on a b engine with a 3.75 throw in a 452 with the b main...never cracked a rod journal...Lol not yet anyway.
            I'd ask whether the b has the block mains enlarged or the main journals turned down. If the main are turned on the crank to fit in the B that likely could be the weak link....it will break there first with big power... it sees more torsion on the main journal vs rod journal. Aftermarket usually has a bigger fillet then you can do w a oem crank to handle more power.
            My guess if it says offset ground it's not a aftermarket crank.
             
            Last edited: May 2, 2020
          • Darter6

            Darter6 FBBO Gold Member FBBO Gold Member

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            When I had my race Slant Six built they off set ground the crank for aluminum rods.
             
          • 66Satellite47

            66Satellite47 FBBO Gold Member FBBO Gold Member

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            Mike, sure sounds like the stock steel crank, offset ground to the 2.2 Chev size, with good rods. Concerns may be rod width (Chev rods narrower effecting oil flow?), does the offset grind eliminate the stock rod throw undercut (good if it does). Those were popular before aftermarket cranks were available.
             
          • 1 Wild R/T

            1 Wild R/T FBBO Gold Member FBBO Gold Member

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            I know you used & highlighted may but I can pretty much assure you on the engine in question thats not the case in Mike's post he mentions
            "high dollar parts such as Manley Steel Rods" well at the time when this was built the reason guys stepped up to Manley steel rods was they made a rod with the Chevy bore & the Chrysler width...
             
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            • 66Satellite47

              66Satellite47 FBBO Gold Member FBBO Gold Member

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              Guess I don't know what's in there. Saw lots of articles that just used the long Chev rods. But???
               
            • MoparLeo

              MoparLeo NRA PATRON LEVEL LIFE MEMBER FBBO Gold Member

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              Getting back to the original question " I have a buddy ..." What are his concerns and what does he intend on using this motor for ??
              That is really the bottom line, not what we think . We all have different experiences and personal opinions.
               
            • 33 IMP

              33 IMP Well-Known Member

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              Manley used to make a specific rod for this application, with chevy journal size, and mopar thickness to have correct rod side clearance on a offset ground mopar stroker. It was mentioned that the engine under discussion has manley rods. Those rods are long discontinued, and now the mopar strokers intending to use chevy rods are sized properly for the chevy big end thickness.
               
            • Mike Gaines

              Mike Gaines Well-Known Member

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              My "buddy" is buying the motor to be a dedicated drag race 71 Duster. He already has the other good parts....Dana 60, Good Tranny, etc,, etc.
               
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