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Buick guys:401/425 Nailhead and Parts interchangeability questions

Discussion in 'The Hokey Ass Message Board' started by Baumi, Nov 10, 2013.

  1. Baumi
    Joined: Jan 28, 2003
    Posts: 1,252

    Baumi
    ALLIANCE MEMBER

    I ´m planning to run a 425 nailhead in my future drag rod project. I already have a beautiful std bore 425 block and a good crank, but the rods and pistons were not with the engine. Some my question is, can I use 401 rods in a 425 block? The stroke is identical at 3.64" but I don´t know if the 425 has the same rod length and compression height as the 401?

    I couldn´t think of a reason why it shouldn´t be identical, but I just can´t find anything about that.I´m dreaming of running a blower with mechanical fuel injection on it. I think a little boost would really help with these small valves and intake/ exhaust runners. How strong is the bottom end on these engines? How much abuse can the nailhead rods take?

    Are there other weak links?
    Thanks for your help! Chris
     
  2. BOBCRMAN
    Joined: Nov 10, 2005
    Posts: 658

    BOBCRMAN
    Member
    from Holly

    Rod length is the same. Block was raised for the longer stroke of the 425
     
  3. Baumi
    Joined: Jan 28, 2003
    Posts: 1,252

    Baumi
    ALLIANCE MEMBER

    Thanks! So the 401-425 blocks are taller than the 364?
     
  4. CTFuzz
    Joined: Jan 31, 2002
    Posts: 2,632

    CTFuzz
    Member

    401/425 have the same stroke, blocks are the same for your purposes. Yes, deck hight is more on the 401/425 than the 364. I wouldn't worry about the bottom end of a Nailhead as long as the boost isn't crazy high.
    Good luck with the project.
     
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  5. Baumi
    Joined: Jan 28, 2003
    Posts: 1,252

    Baumi
    ALLIANCE MEMBER

    Thanks for the good info! All I have left to do is collecting parts, hahaha
     
  6. models916
    Joined: Apr 19, 2012
    Posts: 192

    models916
    Member

  7. hidez57
    Joined: Jan 29, 2006
    Posts: 179

    hidez57
    ALLIANCE MEMBER

  8. 4284555sd
    Joined: Jun 29, 2009
    Posts: 62

    4284555sd
    Member

    Buick Rods and crank are steel with small mains. Strong lower end. Worry more about pistons. Getting the right piston is getting hard. They move the pins up to lower the comp. Egg is bad about this. You'll have to have some made. Try not to use cast.
     
  9. telriv
    Joined: Aug 24, 2005
    Posts: 67

    telriv
    Member
    from Conn.

    I've spent close to 2 yrs. coming up with a universal FORGED piston for the 401/425 engines. It has finally come to a reality. $795.00 includes pins, locks, pin fitting & 1/16th. or 5/64ths. standard ring combos. Taking deposits now. Once I have ALL your specs. will be 5-8wks. Each set is custom made for each particular set-up. Can read MUCH more about this on v8buick.com search Tom Telesco
     

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