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Technical Holley 4 BBL ID

Discussion in 'The Hokey Ass Message Board' started by blowby, Jun 15, 2015.

  1. blowby
    Joined: Dec 27, 2012
    Posts: 7,516

    from Nicasio Ca

    Scored a free carb. Well free but stuck. No air horn, and very well removed if a home job. Did they come that way from Holley? 4781 on metering block. What's the best soak to free throttle plates and screws before disassembly? Corroded, not gummed up.

  2. yes, some came without air horn (performace models) model number is stamped on the air horn ....if you have one. don't know where to look on your model. In Holley terms, the model # is called a list#.
  3. mjlangley
    Joined: Dec 11, 2008
    Posts: 170

    from SE MI

    List #4781 is an 850 double pumper I think. Best bet is to get on the holley website and check the throttle bore sizes and other measurements to verify.
  4. Stock Racer
    Joined: Feb 28, 2010
    Posts: 702

    Stock Racer

    That's a 850. Spray it down with some Gibbs or something similar.

  5. Mark T
    Joined: Feb 19, 2007
    Posts: 1,897

    Mark T

    Soak the throttle blades and shafts with some Kroil, its supposed to creep into a millionth of an inch space.

    Here is their website -
  6. blowby
    Joined: Dec 27, 2012
    Posts: 7,516

    from Nicasio Ca

    Thanks for the info and advice guys.
  7. Larry T
    Joined: Nov 24, 2004
    Posts: 7,661

    Larry T

    If the outside is that rough, you probably need to at least pull the bowls and metering plates to see what the inside looks like. The carb has been modified, so you need to check jets/etc. to see what's been done to it and baseline the carb. 850 might be a bigger carb than you need unless your running lots of cubic inches and/or lots of rpms.
  8. aaggie
    Joined: Nov 21, 2009
    Posts: 2,531


    Usually when someone mills off the choke they also take off the ring that centers the air cleaner so yours may be a factory job. Spray it down with Gibbs or PB Blast for a few days then carefully take it apart.
  9. saltflats
    Joined: Aug 14, 2007
    Posts: 10,733

    from Missouri

    I thought it looked factory because of the breather locating notches.

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