The vacuum break assembly...
The vacuum break assembly is a crucial part of the choke and secondary air valve operation. A vacuum diaphragm pulls the choke valve slightly open at startup, enabling a rich mixture for cranking and firing, followed by a slightly leaner mixture for warm-up. Clean this assembly in alcohol to prevent damaging the diaphragm!
Restoring the original Quadrajet carburetor will preserve your Corvette's value. You should avoid purchasing a "rebuilt-exchange" carburetor. Due to the mass-produced, similar architecture of the Quadrajet, a host of applications will fit your Corvette engine's manifold. However, neither a Buick 231 V-6 nor a 454 V-8 application will have the fuel metering components or tuning calibrations for a Corvette 350 V-8. Keep the original castings, jets, and metering rods!
Use quality parts when rebuilding a Quadrajet. Modern carburetor kits contain extra gaskets to allow wider model coverage. Be careful when matching gaskets to the originals. Small differences can create air or fuel leaks and poor performance. The stamping number on the carburetor identifies the carburetor's original application and the gasket kit needed.
Find a clean, dust-free place to work on your carburetor. Follow the steps shown and use a factory workshop manual to confirm specifications. Compare details with the instruction sheet found in a quality rebuild kit. Properly restored, your Corvette's Quadrajet will provide years of impressive performance-and fuel savings, too!
| Difficulty Index - 2 Wrenches |
| Anyone’s Project: no tools required | 1 Wrench |
| Beginner: basic tools | 2 Wrenches |
| Experienced: special tools | 3 Wrenches |
| Accomplished: special tools and outside help | 4 Wrenches |
| Professionals Only: send this work out | 5 Wrenches |
After removing the vacuum...
After removing the vacuum break assembly, remove the clip that retains the choke link rod at the choke valve's arm. Slide the rod and lever from the main carburetor body and air horn slot. Note the orientation of the rod and lever for reassembly. The rod and lever can be challenging parts to install.
The spring roll pin can remain...
The spring roll pin can remain in the top section (air horn) of the carburetor during service work. Using a tiny pin punch, gently move the spring roll pin inward to release the accelerator pump lever. If the pin slides too easily or shows wear on its friction surface, most carburetor kits contain a replacement pin. Remove the pump rod link.
Secondary metering rods are...
Secondary metering rods are calibrated and precisely shaped. Use care removing the rod holder and rods. The screw is often a Torx head. Protect these metering rods and reinstall them with care. Considered an emission control item, these rods are nearly impossible to find. Federal emission regulations prohibit the sale of aftermarket rods.
The air horn can now be removed....
The air horn can now be removed. Loosen all hold-down screws (nine in this application). Air horn lifted, you can see the accelerator pump, float assembly, power piston, and primary metering rods. Never force pieces apart. Do not pry at the gasket surfaces. The body and sealing edges are softer metal and can be easily damaged.
Gently pull upward on the...
Gently pull upward on the power piston. The sleeve seal is hard plastic and seats snugly into the main body bore. Carburetor kits do not include a new sleeve seal, which is regarded as an integral part of the power piston. Primary metering rods are brass and must be handled with care. The rod retainer spring keeps rods aligned.
Stale fuel, a dry fuel bowl,...
Stale fuel, a dry fuel bowl, or corrosive conditions contribute to carburetor troubles. Original, closed-cellular plastic floats were susceptible to damage and porosity. Surface scratches or a fingernail dent can cause a plastic float to fail. Never soak a plastic float in carburetor cleaner. A practical upgrade is the brass replacement float shown, which this carburetor acquired in an earlier rebuild.
Loosening two screws removes...
Loosening two screws removes the lower throttle body. Shown here is the gasket that seals between the throttle body and main body. Note the factory use of epoxy at the fuel chamber plugs. This added protection helps prevent seepage from the plugs. Do not remove this epoxy coating.
Verify the condition of critical...
Verify the condition of critical parts. Dip metal parts in carburetor cleaner. When selecting a cleaner, read labels and follow cleaning instructions. A California-approved cleaner will generally work as well as the highly toxic 49-State chemicals. Do not soak the vacuum break diaphragm, plastic float, or plastic float bowl insert.
Carburetor dip, a thorough...
Carburetor dip, a thorough rinse, and compressed air cleaning of all tubes, nozzles, and venturi passageways have this throttle body, main body, and air horn looking like new! When handling a carburetor or carburetor cleaner, use chemical-proof gloves, eye protection, and a respirator mask. Exposure to gasoline and VOC cleaners is unhealthy.