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Mystery numbers on FL flywheel edge?

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  • Mystery numbers on FL flywheel edge?

    Are these numbers of any significance? The wheels in this 50 FL I just acquired appear to be OEM as far as I can tell without splitting the case, however it was built with an S&S rod set. Last time it was apart was in the mid/late 70's I believe.
    Attached Files

  • #2
    FL not but EL cases were stamped with 7s on top of the rear engine motor mount in those days of near-identical 74 and 61 engines being built in the Milwaukeee factory simultaneously. Another way the factory had of telling them apart in 1950? Looks pretty "official" 2me.
    Gerry Lyons #607
    http://www.37ul.com/
    http://flatheadownersgroup.com/

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    • #3
      Hard to say what those numbers mean. I am going to hazard a guess that those flywheels are not OEM. Generally HD flywheels do not have balancing holes by the crankpin. The rod relief cutouts appear like later HD and not 1950 if I remember right. Either those S&S rods are way heavier than stock which is possible or it is a stoker or the flywheels are non OEM.

      Jerry


      Originally posted by Hack View Post
      Are these numbers of any significance? The wheels in this 50 FL I just acquired appear to be OEM as far as I can tell without splitting the case, however it was built with an S&S rod set. Last time it was apart was in the mid/late 70's I believe.

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      • #4
        S&S rods are heavier than stock, so if stock flywheels then they may have been re-balanced by the holes shown.
        Bob Rice #6738

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        • #5
          Thanks for the input guys, yeah there is enough suspicious stuff going on to make me wonder too, but not enough to verify. Next month or so I'll be ready to rebuild it and will find out for sure what is going on when I crack the cases. I always wanted to build a Pan with the UL wheels I've been sitting on, maybe this will provide an excuse. The left wheel has a single timing mark followed by a dot, so I'm thinking maybe they are OEM wheels. Thanks.
          Last edited by Hack; 01-28-2019, 10:45 AM.

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          • #6
            UL wheels have the same shaft tapers as 1930-54 OHV (1" shaft), but smaller pin tapers (1-1/8") so you must either:
            1. Modify the tapers to to accept the larger FL pin. This is lots of work, and despite some very imaginative articles (Easyriders) offsetting the taper gives a very small stroke increase (2.9%), all of the math is wrong.
            2. Use the 1940-52 stepped EL/UL pin (1-1/8" tapers, 1-1/4" journal) with your OHV rod set
            The new stroke (with stock 150-372/4 wheels) is 4-9/32" (4.28125"), for which no stroker piston is still made. The 4-1/4" OHV piston will work but check for skirt to flywheel OD and piston to head clearances since they will each close up by 1/64" (.015625").
            The UL OD is smaller than the FL wheels by 7/32" (1937-39) or 3/16" (1940-48) and should have the case scraper built up to work as intended.
            The UL balance weight will be way off.
            IMHO, more work than it's worth. Sell the UL wheels to someone with a UL basket case, and get commercial 4-1/2" wheels, you'll be much happier. Shameless self-promotion: yes, I sell them. http://victorylibrary.com/84OHV.htm
            The Linkert Book

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