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Home >> GMC >> 1982 >> Magnavan Standard Trans >> Repair and Diagnosis >> Engine Performance >> Fuel Delivery >> ROCHESTER Models M4MC & M4ME 4-Barrel >> Overhaul >> Disassembly >> Float Bowl

Float Bowl

  1. Remove air horn gasket by lifting out of dowel locating pins. Lift tab of gasket from beneath power piston hanger, being careful not to distort springs holding main metering rods.
  2. Remove pump plunger and return spring from pump well. Remove power piston and metering rods by depressing piston stem and allowing it to snap free. Repeat until piston force dislodges retainer. Do not use pliers on metering rod hanger to remove power piston. Remove power piston spring from well.
    NOTE: The adjustable part throttle (APT) metering rod adjustment screw is located in a well next to power piston well. The APT is preset at the factory and no attempt should be made to alter its setting. If a new float bowl is required, it will contain a preset APT screw.
  3. Remove metering rods from power piston by disconnecting tension spring from top of each rod. Rotate rods out of hanger.
  4. Remove plastic filler block located over float valve. Remove float assembly and fuel inlet needle by pulling up on retaining pin. Remove inlet seat and gasket. Remove aneroid cavity from float bowl, if equipped.
  5. Remove primary main metering jets. Remove pump discharge check ball retainer and check ball. Do not remove secondary metering jets. These jets are fixed in place, and if damaged, float bowl must be replaced.
  6. Remove secondary air baffle, if replacement is required. Remove secondary vacuum break attaching screws. Rotate vacuum break assembly to remove vacuum break rod from slot in plunger head. On M4ME models, do not remove the non-adjustable vacuum break link at this time.
    Fig 1: Exploded View Of Rochester Model M4MC And M4ME 4-Barrel Carburetor
    G09360555Courtesy of GENERAL MOTORS COMPANY
  7. Align a.159" (No. 21) drill on choke cover retaining rivet and drill only enough to remove rivet head. Repeat for remaining 2 rivets. Drive remainder of rivets out of choke housing. Remove choke cover and coil assembly.
  8. Remove choke housing retaining screw located inside choke housing. Slide complete choke assembly from float bowl. Remove plastic tube seal from choke housing (M4MC models). On M4MC models, do not remove baffle plate from below coil on choke cover.
  9. On M4ME models, remove non-adjustable vacuum break link. On all models, remove secondary throttle valve lockout lever from float bowl. Remove lower (inside) choke lever from inside float bowl cavity.
  10. Remove choke coil lever retaining screw at end of intermediate choke shaft. Remove lever. Slide intermediate choke shaft from choke housing. Remove fast idle cam from intermediate choke shaft. On M4MC models, remove and discard cup seal from inside choke housing shaft hole.
  11. On all models, remove cup seal (intermediate choke shaft) from float bowl insert for bowl cleaning. Do not attempt to remove plastic insert.
  12. Remove fuel inlet nut, gasket and filter. Remove throttle body-to-float bowl attaching screws and throttle body. Remove throttle body-to-float bowl insulator gasket.
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