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Projects rochester 4gc help

Discussion in 'The Hokey Ass Message Board' started by young olds, Jun 25, 2014.

  1. young olds
    Joined: Oct 9, 2009
    Posts: 151

    young olds
    Member

    I have a rochester 4 jet on my daily driver and whenever i turn or stop its idles down and almost dies, has a couple times. The engine idles, takes off and drives fine its only while stopping or turning. Ive tried raising my float level, any ideas?
     
  2. 55Brodie
    Joined: Dec 15, 2008
    Posts: 746

    55Brodie
    Member

    Slop in the throttle bores maybe? Or might need a dashpot.
     
  3. young olds
    Joined: Oct 9, 2009
    Posts: 151

    young olds
    Member

    whats the dashpot? this is my first experience with a 4gc
     
  4. I don't have a solution but I'm sure gonna watch and see what they recommend. I'm having a similar problem on mine. It'll be fine with the choke on but as soon as its off it dies. At stop signs, whatever, if I don't keep some pedal going it's out. Yesterday I resorted to swapping a Holley 600 on there and all is well but that didn't really fix anything.
     

  5. 55Brodie
    Joined: Dec 15, 2008
    Posts: 746

    55Brodie
    Member

    Dashpot is a small diaphragm that abuts the throttle arm and slowly bleeds off when the throttle closes. It is meant to help prevent stalling. Mostly found on automatic transmission cars.
     
  6. Do you have any sense of whether it's going rich or lean when it begins to stall out? If it's going too rich then raising the float level may just aggravate the problem. Is the choke adjusted and working properly? Have you done any other work to the car recently?
     
  7. young olds
    Joined: Oct 9, 2009
    Posts: 151

    young olds
    Member

    It seems to like its going lean, almost like im out of gas. thats why i raised the float, which actually made it worse. Idk if the choke is adjusted properly but seems to work fine.
     
  8. PackardV8
    Joined: Jun 7, 2007
    Posts: 906

    PackardV8
    Member

    The 4Jet secondaries will sometimes not close completely. Then when the primary curb idle and air/fuel is adjusted to compensate, the transition is not right.

    Start over. Very lightly tap the secondary arm to insure it's closed. Then follow the Shop Manual sequence to set the air/fuel and the curb idle speed.

    Stopping or turning? Does your car have PS? The load from the PS pump can be like AC compressor and require a bit extra. That's why many auto/AC/PS cars have the throttle dashpot or a throttle kicker solenoid. Some dashpots were manual and spring and/or vacuum operated; some throttle kickers had an electric solenoid which activated when the AC was on.



    jack vines
     
  9. young olds
    Joined: Oct 9, 2009
    Posts: 151

    young olds
    Member

    My car does it during stopping or turning, or both simultaneously. I'll look over the carb and see if everything is right. It does have power steering
     
  10. young olds
    Joined: Oct 9, 2009
    Posts: 151

    young olds
    Member

    I think the engine is slowing down while stopping because my transmission waits to downshift until the last second before your stopped and its slowing the engine down like when you dont push the clutch pedal in on a manual. While turning its a definite stumble/something, I did take the carb off and go through it a little and readjusted the floats and its better doesnt seems to do it if i turn and am off the gas.
     

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