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Hot Rods 426 HEMI flywheel bolt size question

Discussion in 'The Hokey Ass Message Board' started by ronnieroadster, Sep 30, 2024.

  1. ronnieroadster
    Joined: Sep 9, 2004
    Posts: 1,114

    ronnieroadster
    Member

    Starting on another engine build for the next family Hot Rod this time its going to be a sixty's power plant. The engine is going to be a 426 HEMI so I'm now learning some of the details involved this week I'm working on a transmission adapter.
    My 426 stock stroke crankshaft has the 8 bolt hole crankshaft flywheel flange the holes are 1/2 -20 thread. My question is did the 426 HEMI ever come with a 7/16 fine thread bolt hole ?
    Ronnieroadster
     
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  2. jimmy six
    Joined: Mar 21, 2006
    Posts: 16,030

    jimmy six
    ALLIANCE MEMBER

    I’ve used the 1/2”-20 thread hemi bolts on my GMC’s 6’s for years. I never saw a listing for any other size…
     
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  3. All I had were 1/2". I used 413 industrial cranks sometimes and they were 1/2". The industrial crank has a longer flange that requires a 392 length input such as when you use a Lenco.
     
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  4. ronnieroadster
    Joined: Sep 9, 2004
    Posts: 1,114

    ronnieroadster
    Member

    Thanks for information the transmission conversion I'm using came with 7/16 hardware for the crank flange but the flywheel and crank spacer both have the correct 1/2 inch holes. Should be a simple correction. So yesterday I contacted the adapter people about the difference now waiting to hear back about if they will be correcting this by supplying the correct bolts.
    Ronnieroadster
     
    RICH B and Desoto291Hemi like this.
  5. sunbeam
    Joined: Oct 22, 2010
    Posts: 6,304

    sunbeam
    Member

    early Heni were 7/16
     
  6. RodStRace
    Joined: Dec 7, 2007
    Posts: 5,617

    RodStRace
    Member

    A smart man might look up the ARP bolts in the size and length he needed, then ask the supplier about those exact part numbers...;)
     
  7. Hemi Joel
    Joined: May 4, 2007
    Posts: 1,584

    Hemi Joel
    Member
    from Minnesota

    All ate Hemis are 1/2-20. What are you adapting over to? Mopar made some decent transmissions that will bolt right up.
     
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  8. ronnieroadster
    Joined: Sep 9, 2004
    Posts: 1,114

    ronnieroadster
    Member

    The wife requested an automatic I want the overdrive option as well. So I need one that will handle at least 600 HP and similar torque numbers. Unfortunately there's no good options for that with the Mopar automatics with overdrive that are not computer controlled transmissions. . I don't want computer controlled anything on this build so Im going to use a different brand.
    Ronnieroadster
     
    Hemi Joel likes this.
  9. George
    Joined: Jan 1, 2005
    Posts: 7,822

    George
    Member

    Originally nutted studs went through the crankflange, might have been 7/16, but you have to run a 1/2-20 tap though them and use the 426 Hemi flex plate/flywheel & bolts.
     
    Desoto291Hemi likes this.

  10. The 46RH isn’t computer controlled,,,,,and it’s a great transmission .
    It’s a 727 with an overdrive,,,,,but controlled with hydraulic pressure .
    There is a simple switch system that is used that operates off of pressure from the governor .

    Tommy
     
  11. Hemi Joel
    Joined: May 4, 2007
    Posts: 1,584

    Hemi Joel
    Member
    from Minnesota

    That's what I have behind the Cummins in my '93 1-ton. No computer at all.
     
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  12. ronnieroadster
    Joined: Sep 9, 2004
    Posts: 1,114

    ronnieroadster
    Member

    Thanks for the info about the 46RH but its way to long don't know of anyone using it in a Deuce. So I'm staying on track with what I'm working with.
    Ronnieroadster
     
    Hemi Joel likes this.
  13. Beanscoot
    Joined: May 14, 2008
    Posts: 3,338

    Beanscoot
    Member

    A 727 with a 2.47 rear end... with that engine you'll still be traction limited!
     

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