'65 401 Carb 3921S Rebuild Surprises

Discussion in 'Carter' started by UntamedKitty, May 7, 2015.

  1. UntamedKitty

    UntamedKitty Janitor

    Looking to replace the 4-Jet on my freshly rebuilt '66 407 Nailhead, mildest cam/springs upgrade with this AFB.

    Decided to freshen up the AFB and upon dis-assembly and cleaning found 120-256 primary jets, which fit a 5/64" drill bit, secondary jets the same size but unmarked, both step up rods bent and one longer than the other measuring .080/.065, the pump discharge check needle missing, and the fuel inlet screen missing. The primary shaft has a little play in it, .010"? Some AL corrosion due to the exhaust gas getting through the base gasket, no SS plate was used.

    What have I got here? And what jets/step up rods should be in here, or what would you guys recommend?
    This is not a race car.

    Thanx in advance for any feedback!
  2. Bigpig455

    Bigpig455 Fastest of the slow....

    Untamed - when I first did the Doc mod on my 401, I made some jet adjustments on my AFB that worked pretty well on a slightly warmed over stocker.....you'll have to go back and find the thread from 3-4 years ago, but it has all the specs.
  3. telriv

    telriv Founders Club Member

    Because of the front metering rods the front jets are ALWAYS larger than the rear jets. The throttle shafts need to be re-bushed.
  4. micmo

    micmo Active Member

    on my 64 riv I put a 600 holly tuned to 13.2 runs great:) lots of power 342 posi
  5. carmantx

    carmantx Never Surrender

    I just built one of these, but I don't recall off the top of my head what the jet sizes were marked. I keep notes on all of my builds, so I could look it up.
    The shaft can be bushed with larger 3/8" bronze bushings. These AFB's also benefit from a non leather accelerator pump. Use the garter spring ethanol resistant pump.

    DEADMANSCURVE my first word : truck

    at work now but from memory the basic 600 edelbrock front jets are 100 , rears are 95 and the standard metering rods are 70 x 47 . that may help give ya a ballpark start .
    edit : yeah , close -
    manual choke 600 : primary jets 100 , rods 70x47 , secondary jets 95 , orange step spring
    electric choke 600 : primary jets 98 , rods 75x47 , secondary jets 95 , yellow step spring
    Last edited: Jun 4, 2015

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