The following disassembly and assembly procedures may vary somewhat between applications due to specific design features. However, they will basically pertain to all Quadrajet models.

We highly recommend you take lots of pictures as you disassemble the carburetor to catalog variations that may not be illustrated here.

DISASSEMBLY

1. Remove idle vent valve attaching screw; then remove idle vent valve assembly. If thermostatic vent valve is used, remove dust cover then remove valve. Care should be used not to bend or distort the bi-metal strip.
2. Remove clip from upper end of choke rod, disconnect upper end of choke rod from upper choke shaft lever. Remove choke rod from lower choke lever in bowl by working choke rod “up and down” until lower end of rod is free from lever.
3. Remove clip from upper end of pump rod; then disconnect pump rod from pump lever. Wire vent valve lever can be removed from pump lever if replacement is necessary.
4. On 1967 and later models remove the vacuum break rod from vacuum diaphragm plunger by removing retaining clip. Remove other end of rod from air valve shaft lever.
5. Remove secondary metering rods by removing small screw at top of metering rod holder. Remove rod holder and rods by lifting straight upward out of air horn. Now remove secondary rods from rod holder by sliding end of each rod out of holder.
6. Remove (9) air horn to float bowl attaching screws. Two counter-sunk screws are located inside air horn born next to the primary venturi.

NOTE: Some Chevrolet models have a secondary baffle plate which is mounted under the two center air horn attaching screws next to the secondary bores. This can also be removed at this time. Others have a choke lockout lever shield located over the lockout lever. This is held in position by the air horn screw next to the lockout lever. Check the parts bulletin for correct usage of these extra parts.

1. Remove air horn by lifing straight up. Air horn gasket should remain on bowl for removal later.

CAUTION: Place air horn inverted on clean bench. Care must be taken not to bend two small secondary main well air bleed tubes and accelerating well tubes (where used). These small tubes protrude from air horn casting and are permanently pressed in place. Do not remove.

AIR HORN DISASSEMBLY

1. (Early models) Remove end of dash pot plunger rod from air valve lever. Some slide out of lever and others are held by a retaining clip. The dash pot piston has a synthetic seal inside the piston on the plunger shaft. This should be be immersed in carburetor cleaner as the seal will be destroyed.

NOTE: Further disassembly of the air horn is not required for cleaning purposes. If part replacement is required, proceed as follows.

1. Remove (2) choke valve attaching screws. Then remove choke valve and shaft.
2. Remove pump lever roll pin and remove pump lever.
3. If the air horn is equipped with the air valve lockout and it needs replacement, remove the lockout lever by driving out roll pin with small drift punch.
4. If the air valve spring or secondary metering rod cam needs replacement, a repair kit is available. To replace these parts, proceed as follows:
   1. Remove air valve spring fulcrum pin lock screw.
   2. Remove air valve spring fulcrum pin from casting.
   3. Remove air valve spring.
   4. Remove (4) air valve attaching screws and remove valves from shaft.
   5. Remove air valve shaft by sliding out of air horn casting. Then plastic metering rod cam can be removed.

No further disassembly of the air horn is required.

FLOAT BOWL DISASSEMBLY

1. Remove pump plunger from pump well.
2. Remove air horn gasket from dowels on secondary side of bowl, then remove gasket from around power piston and primary metering rods.
3. Remove pump return spring from pump well.
4. Remove plastic filler block over float valve.
5. Remove power piston and primary metering rods as an assembly.

There are four different type power piston retainers used. (see below)

1. Remove primary metering rods from power piston by disconnected tension spring loops from top of each rod. Then rotate each metering rod to remove from hanger.

CAUTION: Use care when disassembling rods to prevent distortion of tension spring and/or metering rods.

1. Remove power piston spring from power piston cavity.
2. Remove needle and seat assembly (see below)

A. The first design has a “button head” pin extension pressed into the base of the power piston. This type power piston is held in place by the “button head” which protrudes through a hole in the throttle body gasket. The power piston can be removed by using needle nosed pliers to pull straight up on metering rod hanger directly over power piston.

B. The second type power piston retainer is a flat brass spring clip which fits around the power piston, at the center. This type power piston assembly is removed in the same manner as above.

C. The third type power piston retainer is a spring clip which fits over and around the top of the power piston cavity. Two fingers at the top of clip hold the piston down in cavity. This type power piston can be removed by pushing upward on the clip retainer to disengage from casting.

D. The fourth power piston retainer is a plastic retainer which is part of the power piston assembly. The plastic retainer fits in a recess at the top of the power piston cavity. The power piston with the plastic retainer can be removed by pushing downward against spring tension and allowing the piston to snap back agains the retainer until it “pops” out of casting.

FLOAT ASSEMBLY REMOVAL

DIAPHRAGM TYPE

1. Remove float assembly by pulling upward on hinge pin until pin can be removed from float hanger by sliding toward pump well. After pin is removed, slide float assembly toward front of bowl to disengage needle pull clip from float arm. Do not distort float needle pull clip.
2. Use needle nosed pliers, remove pull clip from float needle.
3. Remove two screws from float needle diaphragm retainer; then remove retainer and float needle assembly from bowl.

CAUTION: Needle seat is factory staked and tested. Do not attempt to remove or restake. If damaged, replace float bowl assembly.

STANDARD TYPE NEEDLE & SEAT

1. Remove float assembly by pulling upward on hinge pin. Float needle and hinge pin can now be removed from float assembly.
2. Remove float needle seat and gasket from float bowl.

NOTE: Float needle and seat are factory matched and tested and should be replaced as a set.

1. Remove primary main metering jets. No attempt should be made to remove secondary metering discs. Normal cleaning is all that is necessary.
2. Remove pump discharge checkball retainer and steel checkball.
3. The baffle plate in secondary bores need not be removed for cleaning purposes. It can be removed for replacement by lifting straight upward, out of slots in side of bores.