This procedure covers removal and replacement of the carburetor throttle body assembly on a 1966 Chevrolet Corvette 327ci V8, including disconnection of linkages, fuel lines, and vacuum hoses.

Warnings

Tools required

Parts

• Carburetor base gasket × 1 — Use OEM specification for Rochester or Holley carburetor
• Fuel line washers/seals × 2 — Use OEM specification
• Throttle body assembly (if replacing) × 1 — Rochester Quadrajet or Holley 4-barrel per original equipment

Preparation

1. Park vehicle on level surface and engage parking brake
2. Ensure engine is completely cold to touch
3. Disconnect negative battery cable to prevent electrical shorts
4. Place fire extinguisher within easy reach of work area
5. Remove air cleaner assembly by removing wing nut and disconnecting PCV hose
6. Position drain pan below carburetor area to catch fuel spillage
7. Take photographs of all linkage positions and vacuum hose routing for reference during reassembly

Procedure

1. 1

   Relieve fuel pressure and disconnect fuel lines
   Using line wrenches, carefully loosen the fuel inlet line at the carburetor bowl. Allow residual fuel to drain into pan. Disconnect the fuel inlet line completely and plug or cap the line to prevent further fuel leakage. If equipped with a fuel return line, disconnect it as well using the same method.
2. 2

   Disconnect throttle linkage
   Remove the throttle rod from the carburetor throttle lever by releasing the clip or cotter pin securing it. Slide the throttle rod off the ball stud. Note the exact position and orientation of all components for reassembly.
3. 3

   Disconnect transmission kickdown linkage
   If equipped with the Powerglide automatic transmission, disconnect the throttle valve (TV) linkage from the carburetor lever if so equipped. This typically involves removing a clip and sliding the linkage rod off its mounting point. Manual transmission vehicles will not have this linkage.
4. 4

   Disconnect choke cable or linkage
   Disconnect the choke cable from the choke lever on the carburetor. If equipped with a mechanical choke, remove the retaining clip and slide the choke rod free. If equipped with an automatic choke, disconnect the choke heat tube by loosening the clamp.
5. 5

   Label and disconnect vacuum lines
   Identify all vacuum lines connected to the carburetor (typically distributor advance, power brake booster, PCV, and various emission control lines). Use masking tape or labels to mark each line's position. Carefully pull each vacuum line off its nipple on the carburetor body. Inspect lines for cracks or deterioration.
6. 6

   Remove carburetor mounting bolts
   Using a socket wrench, remove the 4 carburetor mounting bolts securing the carburetor to the intake manifold. Keep track of any washers or spacers under the bolt heads. Support the carburetor with one hand while removing the final bolts to prevent it from dropping.
7. 7

   Remove carburetor assembly
   Carefully lift the carburetor straight up off the intake manifold studs or bolt holes. Keep the carburetor level to prevent fuel spillage from the bowl. Place the carburetor on shop rags in the drain pan to catch any remaining fuel. Be careful not to damage the throttle plates or linkage during removal.
8. 8

   Remove old gasket and clean mating surface
   Remove and discard the old carburetor base gasket from the intake manifold surface. Use a gasket scraper to carefully remove all gasket material from the intake manifold mating surface. Do not allow debris to fall into the intake manifold ports. Stuff clean rags into the manifold openings to prevent contamination. Clean the surface with carburetor cleaner and wipe dry.
9. 9

   Prepare replacement throttle body
   If installing a replacement carburetor, verify it matches the original configuration and CFM rating. Transfer any necessary components (fuel fittings, vacuum ports) if required. Ensure all passages are clean and throttle plates move freely. Remove protective plugs from ports and openings.
10. 10

    Install new base gasket
    Remove rags from intake manifold ports. Position the new carburetor base gasket on the intake manifold, ensuring all bolt holes and ports align correctly. The gasket should lie flat with no wrinkles or folds. Some gaskets may have an orientation mark indicating front of engine.
11. 11

    Install throttle body assembly
    Carefully lower the carburetor onto the intake manifold, aligning the mounting holes with the studs or bolt holes. Ensure the gasket remains properly positioned and does not shift. Insert all 4 mounting bolts with any original washers or spacers. Hand-tighten bolts in a crisscross pattern to ensure even seating.
    Torque spec

    Throttle Body Bolts10 Nm (7 lb-ft)
12. 12

    Torque carburetor mounting bolts
    Using a torque wrench, tighten the 4 carburetor mounting bolts to specification in a crisscross pattern (front left, rear right, front right, rear left). This ensures even clamping force and prevents gasket leaks or warping of the carburetor base. Make a second pass to verify all bolts are at specification.
    Torque spec

    Throttle Body Bolts10 Nm (7 lb-ft)
13. 13

    Reconnect vacuum lines
    Reconnect all vacuum lines to their original positions using the labels or photographs from disassembly. Ensure each line is pushed fully onto its nipple and seated properly. Verify no lines are kinked, twisted, or in contact with hot engine components.
14. 14

    Reconnect choke system
    Reconnect the choke cable or linkage to the choke lever. Ensure proper operation by moving the choke plate by hand to verify full range of motion. If equipped with automatic choke heat tube, reconnect and secure with clamp.
15. 15

    Reconnect throttle linkages
    Reconnect the throttle rod to the carburetor throttle lever ball stud and secure with the original clip or new cotter pin. Reconnect the transmission kickdown linkage if equipped. Verify smooth throttle operation by having an assistant press the accelerator pedal while you observe linkage movement. Throttle should open fully and return completely to idle position.
16. 16

    Reconnect fuel lines
    Install new fuel line washers or seals if applicable. Using line wrenches, reconnect the fuel inlet line to the carburetor bowl inlet fitting. Tighten securely but do not over-torque brass fittings. Reconnect fuel return line if equipped. Remove plugs or caps from lines.
17. 17

    Reinstall air cleaner assembly
    Position the air cleaner base on the carburetor and align with mounting stud. Reconnect PCV hose to air cleaner. Install air cleaner wing nut and tighten securely. Do not over-tighten as this can crack the air cleaner housing.

Reassembly

1. Reconnect negative battery cable
2. Prime fuel system by turning ignition key to ON position (not START) for 5 seconds, then OFF, then ON again to allow fuel pump to fill carburetor bowl
3. Check for fuel leaks at all connection points before starting engine
4. Initial startup may require slightly extended cranking as carburetor bowl fills

Verification

• Inspect all fuel line connections for leaks with engine running
• Verify smooth throttle response from idle to wide open throttle with no binding or sticking
• Check for proper idle speed and quality (adjust idle mixture and speed screws as needed)
• Verify all vacuum lines are connected and no hissing sounds indicate vacuum leaks
• Confirm choke operation if equipped (should close when cold, open when warm)
• Test drive vehicle to verify proper acceleration and no hesitation under load
• Re-check all connections after test drive for any signs of fuel or vacuum leaks

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