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Technical Rochester 2GC worn accelerator pump shaft

Discussion in 'The Hokey Ass Message Board' started by Hotrodjohn71, Oct 4, 2021.

  1. Hotrodjohn71
    Joined: Feb 25, 2018
    Posts: 74

    Hotrodjohn71

    Hi fellas. The accelerator pump shaft / bore is pretty worn out on my Rochester 2GC (1965 Pontiac 326) .
    It's pretty floppy in the bore and I have a bit of stumble when I crack the throttle because of the slop, threes a lack of innital fuel squirt.
    Do you have any suggestions for a repair, or just buy a new carb top and shaft?
    My hunch is that the pot metal carb top is probably worn instead of the steel shaft.
     

    Attached Files:

  2. Johnny Gee
    Joined: Dec 3, 2009
    Posts: 9,792

    Johnny Gee
    Member
    from Downey, Ca

    First off, is the pump the correct size? There are different diameter units for Rochesters.
     
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  3. jimmy six
    Joined: Mar 21, 2006
    Posts: 10,984

    jimmy six
    ALLIANCE MEMBER

    Buy another old carb and put your center and throttle plate so the linkage will work. There are a lot of different top styles and you don’t show what your choke actuator looks like. I see a lot online. If you have a friend with a lathe and a piece of brass round rod…. Make a bushing. You can drill out yours with a good drill press and a good selection of drills. You only need a thou or 2 for clearance.
     
    Last edited: Oct 5, 2021
  4. Bob Lowry
    Joined: Jan 19, 2020
    Posts: 911

    Bob Lowry

    Jimmy Six makes good sense..it's not in a critical area like in the throttle bores..get it close and you'll be great.
    Hobby stores or Ace Hardware normally have brass rod material in short lengths.
     
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  5. There's probably also some check valves or check balls and springs for the accelerator pump inlet and outlet passages. Make sure they're in the proper places and not sticking.
     
  6. carbking
    Joined: Dec 20, 2008
    Posts: 3,292

    carbking
    Member

    A small lathe is a wonderful tool, and I don't know why most enthusiasts do not have one. It was the third major tool I purchased (after a timing light and a portable engine analyser). Sears used to sell them. There is a U.S. company by the name of Sherline that makes a quality small lathe (also milling machine) quite reasonable in price. Sherline made the lathe/milling machines that were sold by Sears.

    The zinc alloy bearing surface in the airhorn where the accelerator pump counter-shaft rotates in the 2G series carbs DOES wear; and a good rebuilder will bush this area.

    For those WITHOUT a lathe, thin-wall splined bushings are available. Measure the diameter of the shaft. Those that I have bushed (those before 1975) have been 1/4 inch; but certainly not going to use the "always" word.

    Jon.
     
  7. Hotrodjohn71
    Joined: Feb 25, 2018
    Posts: 74

    Hotrodjohn71

    Thank you for the replies. Check ball, plunger and bore are in fine condition. Thank you for the ideas. Do you think they make one of those splines bushings for this application?
     

    Attached Files:

  8. jimmy six
    Joined: Mar 21, 2006
    Posts: 10,984

    jimmy six
    ALLIANCE MEMBER

    McMaster-Carr shows an oil lite bushing 1/4” ID and 3/4” long if you can drill the carb top out to 5/16”… It’s $1.12. .1/2” long is less . . . Probably the the best OD your going to find.
    I get McMaster in one day or drive up to the warehouse; your delivery may vary.
     
    Last edited: Oct 5, 2021
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  9. hepme
    Joined: Feb 1, 2021
    Posts: 165

    hepme
    Member

    "floppy in the bore" sure sounds like a too small pump. If its a big base 2gc i'd bet it has the larger size pump that's required. Go to Mike's carb site and he has a video showing the difference in the pump sizes.
     
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  10. saltflats
    Joined: Aug 14, 2007
    Posts: 11,249

    saltflats
    Member
    from Missouri

    Just go to your local hardware store and get a piece of brass tubing that fits your pump lever. Drill for a snug fit for the tube and Loctite or epoxy the tube in place.
    I have fixed many this way.
     
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  11. seabeecmc
    Joined: Jan 28, 2005
    Posts: 1,092

    seabeecmc
    ALLIANCE MEMBER

    [​IMG]Vintage Speed repair kit. Worked for me. Ron
     
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  12. Hotrodjohn71
    Joined: Feb 25, 2018
    Posts: 74

    Hotrodjohn71

    I found a bushing at a local Tractor Supply. Cut it to length, then drilled the hole in the air horn to allow some interference fitting and now it's perfect. Better than new.
    Thanks a million for helping me get this done.
     

    Attached Files:

  13. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,596

    sunbeam
    Member

    I have done this on throttle shafts if there is enough materal find an old 1/8 pipe brass fitting drill the hole and tap to 1/8 pipe screw fitting in and cut it flush. Then drill the inside of the fitting to shaft size.
     
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  14. jimmy six
    Joined: Mar 21, 2006
    Posts: 10,984

    jimmy six
    ALLIANCE MEMBER

    Looks like the McMaster one. There are Hillman drawers at the ACE I use; bet there was one there too.
     
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