Needs help with Rochester M2MC-Carburation

Discussion in 'General Automotive Tech' started by tenner21, Apr 25, 2019.

  1. tenner21

    tenner21 Member

    Joined:
    Mar 6, 2019
    Messages:
    45
    Likes Received:
    4
    Trophy Points:
    9
    Hello Wagon-friends,

    I have a very huge problem with the Carburator of my '79 Catalina Safari, A Rochester 2-Barrel M2MC.
    The problem ist like the following description:

    Starting the engine, the Primary Pull-Off will open the Choke plate for more fresh air.
    The ideling during warm-up ist much higher than in hot condition, so the Wagon will drive without a gas pedal command from my foot. Ok - so long.
    The problem occures, when I push the pedal downwards. If I drive on the country road and try to drive faster than in idle, my engine stutters very hard and in my mirror - a cloud of black exhaust gases are visible.

    The funny side: After warmup-sequency, the engine runs smooth and with a good power, with no stuttering or anything else.

    Because anybody had changed the whole underpressure-system to a big peace of shit, I organized all new parts to get the original underpressure-system back. In this way, I overhauled the carburator, because it was a multiple leakage.


    In case of troubleshooting I guess, that the Idle Mixture Screw and the CO-Screw are faulty adjusted.
    My question to you:
    Does anybody know, how I restore the factory setting or how I have to adjust the M2MC right?
    I would very pleased, if anybody tries to help me.


    Best regards from germany - Maik
     
  2. Silvertwinkiehobo

    Silvertwinkiehobo "Everything that breaks starts with 'F.'"

    Joined:
    Apr 21, 2014
    Messages:
    14,928
    Likes Received:
    2,950
    Trophy Points:
    710
    Location:
    New Braunfels, TX
    I can tell you two things: 1) the high idle is either adjusted too high or the choke thermostat is adjusted wrong; 2) you are getting too much fuel into the engine at cruise, and the choke makes it show up. Once the choke is fully open and down at curb idle, you don't see it as well, but I would bet it is there. So, if you can give me the carburetor number, which is on the throttle side of the body, I'll see if one of my books has the specifications for it, and adjustment instructions.
     
  3. cammerjeff

    cammerjeff Longroofs Rule!

    Joined:
    Aug 30, 2008
    Messages:
    5,187
    Likes Received:
    904
    Trophy Points:
    427
    Location:
    Belleville, MI
    I agree that it sounds like the choke is not coming fully off. Is it a Hot Air Choke or an electric choke?
     

Share This Page