Carburetor start-up.

Discussion in 'The Mixing shop.' started by jhems17, Nov 12, 2018.

  1. jhems17

    jhems17 Well-Known Member

    Hey everyone, I'm sure this topic is in here somewhere but I cant seem to find it so sorry if it's a repeat. I have a '71 Riviera with the original Quadrajet in it. When I start it in the morning it has the regular idle. I have to hold down the accelerator to warm it up without it stumbling off. Isn't it supposed to start at a higher idle (what's that called) and once warm I should be able to hit the gas pedal real quick to drop it down to regular idle? I had a '72 that worked this way. I cleaned the carb with cleaner and started it, I see the choke almost fully closed and open up as it gets warmer. It drives fine it's just this cold start issue. Any suggestions? Thanks.
  2. johnriv67

    johnriv67 Well-Known Member

    What you are talking about is the fast idle kick down. When you started the car, did you give one pump of the pedal to the floor and then back?
  3. carmantx

    carmantx Never Surrender

    If your choke is working, closing as you mention, then the fast idle cam should be engaged. You can adjust the fast idle speed with small screwdriver on passenger side of carb, facing forward.

    BUICKRAT Torque Rules!

    Linkage is stuck, fast idle screw is wrong, or, Most likely, the choke thermostat is stuck/junk. Spray the choke linkage down with penetrant and work it, you may have to adjust the fast idle cam screw, or find an old guy that knows carb adjustments.

    you may have to learn how a carburetor works
  5. jhems17

    jhems17 Well-Known Member

    Johnriv67, thanks for the response, love the '67, I actually pump it a couple times only because I don't drive it daily, more like weekly if that so I feel the bowl may be empty from evaporation from the warm LA weather. But I do see in the owners manual it says "Cold weather, depress once fully and crank". So what are you thinking?
  6. jhems17

    jhems17 Well-Known Member

    Carmantx, I will look into that as well. I bought the Doug Roe Rochester book so will be learning and trying to fix these issues. If you know any "Carb Guys" in the Los Angeles area please point me to them. Once I get the car where I want I will definitely want to tune it proper. Thanks for the help.
  7. jhems17

    jhems17 Well-Known Member

    Thanks for the input guys, this gives me a great starting point.
  8. TrunkMonkey

    TrunkMonkey Well-Known Member

    (extra info)

    With the ignition off, pressing the pedal full to the floor, then releasing sets the choke (if it is adjusted correctly) and provides a full shot from the accelerator pump.

    Then start without "pumping the pedal", and it should start.

    If you "flood" the engine, the remedy is to push and hold the pedal to the floor, and crank the engine. This will prevent added fuel form being introduced from excessive "pumping" of the pedal (and the continual fuel added by the accelerator pump), and "clear" the engine of excess fuel.

    And if cold, the choke will remain set correctly. If warm, then it clears the flooding condition.

    But, the carb and choke need to be working properly and be adjusted properly.

    Those who "pump" the pedal to start, are creating a condition that drastically shortens engine life by washing down the cylinder oiling and speeds up wear to rings and upper cylinder walls.
    BuickV8Mike likes this.

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