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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
    Joined: Jan 2, 1995
    Posts: 15,165

    Ryan
    ADMINISTRATOR
    from Austin, TX
    Staff Member

  2. HOTRODSURFER
    Joined: Sep 11, 2006
    Posts: 5,845

    HOTRODSURFER
    Member
    from HATBORO,PA

    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
    Joined: Oct 22, 2007
    Posts: 35

    Magneto349
    Member

    Sweet! Another thing to put in my flathead notebook! Thank You!
     
  4. Retroharley
    Joined: Jan 3, 2007
    Posts: 123

    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
    Joined: Sep 14, 2004
    Posts: 1,642

    skajaquada
    Member
    from SLC Utard

    i always thought it was the waterneck location that gave them away...?
     
  6. srosa707
    Joined: Jun 5, 2005
    Posts: 1,551

    srosa707
    Member
    from Sacramento

    Thanks for clarifying.
     
  7. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 19,658

    Bruce Lancaster
    Member

    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
    Joined: Nov 13, 2002
    Posts: 736

    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
    Joined: Feb 13, 2007
    Posts: 11,750

    pasadenahotrod
    Member
    from Texas

    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
    Joined: Jul 24, 2002
    Posts: 3,270

    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
    Joined: Jun 26, 2006
    Posts: 2,002

    SlamCouver
    Member
    from Brazil, IL

    Awesome bit of info, if you remember other tricks let us know! i require tricks and tips.
    thanks
     
  12. Lil' Lance
    Joined: Nov 3, 2006
    Posts: 99

    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
    Joined: Jul 31, 2007
    Posts: 88

    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
    Joined: Aug 23, 2004
    Posts: 2,623

    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
    Joined: May 13, 2002
    Posts: 3,258

    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
    Joined: May 5, 2006
    Posts: 1,124

    73roundlight
    ALLIANCE MEMBER

    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.
     

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  17. synthsis
    Joined: Mar 29, 2006
    Posts: 1,899

    synthsis
    Member

    just more info for me to absorb. thanks for the write-up!
     
  18. 1950ChevySuburban
    Joined: Dec 20, 2006
    Posts: 6,216

    1950ChevySuburban
    Member Emeritus
    from Tucson AZ

    I like that little trivia stuff!
     
  19. Old Roadster
    Joined: Jul 2, 2006
    Posts: 616

    Old Roadster
    Member

    Good Stuff.......
     
  20. Cyclone Kevin
    Joined: Apr 15, 2002
    Posts: 2,572

    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
    Joined: Oct 16, 2007
    Posts: 1,221

    Noland
    Member

    Thanks

    I always wondered
     
  22. continentaljohn
    Joined: Jul 24, 2002
    Posts: 3,270

    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. Have you noticed the date on this thread?
     

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