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Flatheads 101: 21 Vs. 24-Stud

Discussion in 'The Hokey Ass Message Board' started by Ryan, Oct 25, 2007.

  1. Ryan
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    Ryan
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  2. HOTRODSURFER
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    HOTRODSURFER Member

    THANKS RYAN!! as a new comer to the flathead scene i still have many questions! and that was one of them-thats why i love the HAMB
  3. Magneto349
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    Magneto349 Member

    Sweet! Another thing to put in my flathead notebook! Thank You!
  4. Retroharley
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    Retroharley Member

    I never knew that. Thanks for sharing. Now I'm going to always clance at the center studs when I see a flathead engine.
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  5. skajaquada
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    skajaquada Member

    i always thought it was the waterneck location that gave them away...?
  6. srosa707
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    srosa707 Member

    Thanks for clarifying.
  7. Bruce Lancaster
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    Bruce Lancaster
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    They came both ways on 21's...
    Probable reason for change: 21 had a stud directly below centers of bores, and boring to 3 3/16 left only a scary amount of iron between stud and bore.
    I think they changed the tooling in preparation for the intro of the bigger bore engines to keep tooling as common as possible between 221 and 239.
  8. ROBERT JAM
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    ROBERT JAM Member

    Hey Ryan that is just great info.Just two days ago I was looking at a flat head and counting the studs.It will be easy now Thanks!
  9. pasadenahotrod
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    pasadenahotrod Member

    32-36 21s had water pumps in the heads.
    37-38 21s had water pumps in front of block like 38-53 24s.

    That stud line is a great tip to identify the stud count. Thansk for the tip.
  10. continentaljohn
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    continentaljohn Member

    21 stud/bolt hard to find speed parts and very expensive (Arm &Leg ) Were the 24 stud/bolt speed goodies are abundant and in a reasonable price range. The 24's also offer a much wider range of speed accessories.
  11. SlamCouver
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    SlamCouver Member

    Awesome bit of info, if you remember other tricks let us know! i require tricks and tips.
    thanks
  12. Lil' Lance
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    Lil' Lance Member

    thats a good way to look to tell the difference. i always before just looked at the bottom of the head. 2 bolts below the bore=24stud, 1 bolt below bore=21 stud. but cool hey either way works!
  13. 36Brua
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    36Brua Member

    Does it hold true a 21 stud head has 5 studs across bottom of head vs 8 on a 24 stud? xYz
  14. Rand Man
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    Rand Man Member

    . . . waterneck location that gave them away...?

    No the 59A series (center) and the later 8BA series (front water neck) both have 24 studs (or bolt holes).
  15. VAPHEAD
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    VAPHEAD BANNED

    That's how I tell at a glance.
    and the 5 are wide spaced,can spot it across the parking lot.
  16. 73roundlight
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    Very interesting.

    Just wanted to throw in another interesting flattie into the mix. This is an aircooled prototype that is in Speedy Bill's museum (that place is worthy of its own feature sometime).

    Thanks for the info Ryan.

    Attached Files:

  17. synthsis
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    synthsis Member

    just more info for me to absorb. thanks for the write-up!
  18. 1950ChevySuburban
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    1950ChevySuburban Member Emeritus

    I like that little trivia stuff!
  19. Old Roadster
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    Old Roadster Member

    Good Stuff.......
  20. Cyclone Kevin
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    Cyclone Kevin Alliance Vendor


    If there was a market that could support this type of 21 stud venture, I'd continue with it. Tooling alone is close to $11.5 K up front.
    Then you still gotta get the casting done,and machine em up. Are HAMBers game to buy if I were to take this chance.
    They'd be in the same price range as the Flatty Caddy's.
    If you need em. Let see what we can make?
  21. Noland
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    Noland Member

    Thanks

    I always wondered
  22. continentaljohn
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    continentaljohn Member

    Kevin, I don't even see many in the cars anymore. Most seem to have been replace with modern iron. I would like to put one together in the future. Keep us in mind for some goodies...
  23. Cajun Kenny
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    Cajun Kenny Member

    Have you noticed the date on this thread?

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