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rebuild ime on carb

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by JimmyJuneau, Oct 6, 2001.

  1. JimmyJuneau

    JimmyJuneau 1/2 ton status

    Joined:
    Apr 11, 2001
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    Location:
    Juneau, Alaska
    Ok I am about to start rebuilding my carb but no one in town has the doug roe book. what do I have to do to take my stock carb off of my 1985 305 ?

    1985 GMC JIMMY
     
  2. Thunder

    Thunder 3/4 ton status

    Joined:
    Jul 20, 2000
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    Location:
    Northeast Nevada
    Heres some generic instructions+ doos and donts for most carbs.
    ALL THE FOLLOWING ITEMS MUST BE CHECKED FOR CONDITION AND PROPER OPERATION:




    * EGR VALVE * VACUUM LEAKS
    * FUEL PUMP & FUEL FILTER * PORTED VACUUM SWITCHES
    * EXHAUST HEAT VALVE * PCV VALVE
    * SPARK PLUGS & PLUG WIRES * PURGE VALVE & VAPOR CANISTER
    * DISTRIBUTOR VACUUM ADVANCE * IGNITION TIMING & DWELL
    * IGNITION SYSTEM COMPONENTS * ENGINE COMPRESSION
    * CATALYTIC CONVERTOR * AIR FILTER
    * AUTOMATIC CHOKE HEAT EXCHANGE TUBE * INTAKE MANIFOLD GASKETS
    (See #11 Below) * OXYGEN SENSOR & "MAP" SENSOR

    IF ALL OF THE ABOVE ARE WORKING PROPERLY, THEN PROCEED WITH INSTALLATION -

    1. Disconnect all hoses from air cleaner and remove air cleaner.
    2. Carefully disconnect fuel line from carburetor. If it is a metal line, use TWO wrenches. A tubing wrench should be used on the line fitting.
    3. Disconnect throttle linkage, choke linkage or automatic choke heat tube, electrical connectors and vacuum lines connected to the carburetor. We suggest vacuum lines be labeled with numbers, beginning at the fuel inlet and going around the carburetor in a clockwise direction.
    4. Remove mounting bolts or nuts. Be sure to put them where they won't fall into the intake manifold and cause engine damage.
    5. Remove old carburetor, being careful not to spill any dislodged loose dirt into the intake manifold. The old carburetor mounting gasket must be COMPLETELY removed from the mounting surface on the intake manifold.
    6. Compare the rebuilt unit to the old one to make sure they match, then carefully transfer all necessary fittings and accessories from the old carburetor to the new rebuilt unit.
    7. The PCV valve should be removed and cleaned or replaced. A sticking or clogged PCV valve will affect carburetor performance. Also check PCV hose and/or tube for blockage.
    8. On FORD engines with the EGR plate under the carburetor, the plate MUST be inspected for corrosion and replaced if necessary. The gasket between the EGR plate and the manifold should be replaced.
    9. Install new mounting gasket, following any markings on the gasket such as "Front", "Top", "Rear" etc. DO NOT use any kind of sealer or cement on the mounting gasket becauseSealers can clog small air passages in the carburetor.
    10. Carefully set the rebuilt carburetor into place on the manifold.
    11. If your vehicle uses an automatic choke heat tube, remove the choke cover from the old carburetor and check for carbon deposits or water accumulation. If such deposits are present, necessary repairs MUST be made or the automatic choke will not operate properly. Heat tube and return air tube (If so equipped) MUST be properly connected and not blocked or the choke will not operate properly.
    12. Flush out fuel pump and fuel lines by turning the engine over with the starter while holding a container (NOT GLASS) under the fuel line to catch the fuel during flushing. Be sure to disconnect coil wire or ignition wire so the engine won't start while flushing.
    13. INSTALL A NEW FUEL FILTER! On units with fuel filter mounted in or on the carburetor, we also recommend installation of a separate "in-line" filter. CAUTION- If the metal fuel line has been cut-off and rubber hose is to be used on it, the cut ends of the metal lines MUST be ground or filed smooth or the rough ends of the metal lines may cut a piece from the inside of the hose, which will get into the carburetor and CAUSE FLOODING.
    14. Re-connect the fuel line. DO NOT use teflon tape or any kind of sealer on fuel inlet fittings because particles can get under the float needle and CAUSE FLOODING. Connect any threaded lines before tightening the carburetor to the manifold, because it is easier to start the threads while the carburetor can still be moved around and this will also help to avoid cross-threading. Don't tighten these lines until the carburetor has been securely mounted.
    15. Connect vacuum hoses. Before connecting hoses from vapor canister, shake them to see if any charcoal granules from the canister have gotten into the hoses. If so, the canister and/or purge valve must be replaced to keep charcoal from getting into the carburetor.
    16. Replace mounting bolts or nuts and tighten EVENLY. DO NOT completely tighten ANY until ALL have been snugged-down to avoid warping or breaking the carburetor base.
    17. Re-connect all linkage such as throttle (don't forget the return spring), transmission kick-down, cruise control and choke, making sure they all operate freely and don't stick or bind. On engines which use a manifold mounted choke thermostat, the thermostat MUST be checked for proper operation. The choke must close completely when the engine is cold, before starting. If not, the thermostat must be replaced or the choke linkage rod must be adjusted.
    18. Start the engine by SLOWLY pumping the accelerator while cranking; remember, it takes several seconds for the fuel pump to fill the carburetor with gasoline. Be aware that the engine should idle faster when it is cold because the choke engages the fast-idle mechanism until the engine warms-up and the choke opens fully. "Fast-Idle" speed can be adjusted as necessary.
    19. Run the engine until it reaches OPERATING TEMPERATURE. The choke MUST open fully when the engine is warmed-up. Idle speed screw (marked with yellow paint) may be adjusted if necessary after engine is warm. Idle mixture screws have been set to proper specifications, but sometimes may need to be adjusted to obtain smoothest idle condition (or to meet emission requirements). If adjustment is needed, turn the mixture screw(s) slowly clockwise (in) until the engine lags, then slowly counter-clockwise (out) until smoothest idle is obtained. THEN re-adjust the idle speed screw to desired speed.
    20. Install a new air cleaner filter element. DO NOT overtighten air cleaner wing nut or the carburetor may be damaged.

    IN CASE OF FLOODING AFTER INSTALLATION:

    Flooding is a COMMON PROBLEM and is usually caused by a piece of metal thread, rubber hose, dirt, teflon tape or other material getting lodged in the float needle and seat. To correct this problem, stop the engine, disconnect the fuel line from the carburetor and PLUG the line (DO NOT ATTEMPT TO HOLD WITH FINGER). Start the engine and let it run until the carburetor runs out of gas and the engine DIES, then re-connect the fuel line to the carburetor and start the engine. This procedure will usually flush out the lodged particles, but it may need to be repeated two or three times. CAUTION: Don't use an air hose to blow air through the needle and seat. This can damage the float and/or gaskets. NOTE: Too much fuel pump pressure, water in the fuel tank, bad purge control valve or stopped-up vapor canister can also cause flooding.

    Heres A link to an exploded view of a Q-jethttp://coloradok5.com/gallery/Thunders-Blaze
    <font color=blue>NEVADA: Where the pavement ends, and the West begins.</font color=blue>
     

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