High Pressure Fuel Pump

This procedure removes and replaces the mechanical fuel pump on a 1966 Chevrolet Corvette 327ci V8. The mechanical pump is camshaft-driven and mounted to the engine block timing cover.

Warnings

Tools required

Parts

• Mechanical fuel pump × 1 — Use OEM specification or AC Delco 461-40972
• Fuel pump mounting gasket × 1 — Use OEM specification
• Fuel pump pushrod (if worn) × 1 — Use OEM specification
• Fuel line copper crush washers × 2 — Use OEM specification

Preparation

1. Park vehicle on level ground outdoors or in well-ventilated area away from ignition sources
2. Allow engine to cool completely for minimum 2 hours
3. Disconnect negative battery cable to eliminate ignition sources
4. Remove fuel tank filler cap to relieve any residual tank pressure
5. Place fire extinguisher within immediate reach of work area
6. Position large fuel catch pan under fuel pump area on passenger side of engine
7. Have multiple shop rags ready to contain fuel spillage
8. Verify replacement fuel pump matches original (single action vs double action design varies by carburetor setup)

Procedure

1. 1

   Disconnect fuel inlet line from pump
   Locate the fuel pump on the passenger side of the engine block, mounted to the timing cover just above the oil pan rail. Using a fuel line wrench, loosen the inlet line fitting (from fuel tank) at the pump body. This fitting is typically 3/8" and may require penetrating oil if corroded. Support the pump body with a backup wrench to prevent twisting. Allow fuel to drain into catch pan. Stuff a clean shop rag into the open fuel line to prevent dirt entry and additional fuel drainage.
2. 2

   Disconnect fuel outlet line from pump
   Using a fuel line wrench, disconnect the outlet line fitting (to carburetor) from the pump body. This fitting is typically 3/8" or 1/2" depending on carburetor setup. More fuel will drain from this line as it contains residual fuel from the carburetor bowl. Allow complete drainage into catch pan. Plug the open line with a clean rag to prevent contamination.
3. 3

   Remove fuel pump mounting bolts
   Locate the two mounting bolts securing the fuel pump to the timing cover. These are typically 1/2" bolt heads. Using a socket and ratchet, remove both bolts completely. Support the pump body as you remove the second bolt to prevent it from falling. Note the bolt length and any spacers or washers for reinstallation in the same configuration.
4. 4

   Remove fuel pump and inspect pushrod
   Carefully pull the fuel pump away from the timing cover. The pump actuating arm will disengage from the pushrod. Immediately look into the mounting hole in the timing cover to verify the pushrod is still in place. The pushrod is a steel rod approximately 5 inches long that rides on the camshaft eccentric. If the pushrod has fallen into the engine, use a magnet retrieval tool to recover it immediately. Remove the pushrod and inspect for wear on both ends. The end that contacts the camshaft eccentric should be smooth with no pitting or scoring. Replace pushrod if wear exceeds 0.020" or if any flat spots are visible.
5. 5

   Clean mounting surface
   Using a gasket scraper, carefully remove all old gasket material from the timing cover mounting surface. Take extreme care not to gouge the aluminum or cast iron surface, as this will create leak paths. Use a wire brush to clean the mounting bolt holes. Wipe the surface completely clean with a shop rag. Inspect the mounting surface for cracks or damage that could prevent proper sealing.
6. 6

   Inspect and lubricate pushrod
   Apply a small amount of engine assembly lube or clean engine oil to both ends of the pushrod (existing or replacement). Insert the pushrod into the hole in the timing cover, ensuring the lower end seats properly in the camshaft eccentric cup. The pushrod should slide in smoothly and rest with approximately 1 to 1.5 inches protruding from the timing cover face. Rotate the engine crankshaft slowly by hand (using a wrench on the harmonic balancer bolt) to verify the pushrod moves in and out smoothly through its full travel range of approximately 0.5 inches.
7. 7

   Install new fuel pump gasket
   Position the new fuel pump mounting gasket onto the timing cover. The gasket has two bolt holes that should align with the threaded holes in the cover. Some gaskets have an adhesive backing; others may require a thin coating of gasket sealer on the timing cover side only (not on the pump side). Ensure the gasket central opening aligns with the pushrod hole.
8. 8

   Position new fuel pump
   Manually rotate the engine crankshaft until the fuel pump pushrod is at its lowest point of travel (fully retracted). This makes installation significantly easier. Position the new fuel pump against the gasket, aligning the actuating arm with the pushrod. The arm should rest on top of the pushrod. Gently press the pump against the timing cover while aligning both mounting bolt holes. You may need to rotate the pump slightly to engage the actuating arm properly with the pushrod.
9. 9

   Install fuel pump mounting bolts
   Thread both mounting bolts by hand to prevent cross-threading. Once both bolts are started, tighten them evenly in an alternating pattern to draw the pump down squarely against the gasket. Final tighten bolts to 18-25 ft-lbs. Do not overtighten as this can crack the pump body or distort the mounting flange, creating leak paths.
10. 10

    Reconnect fuel lines
    Remove the rags from the fuel lines. Inspect the line ends for damage or distortion. Install new copper crush washers on both the inlet and outlet fittings if your pump uses banjo-style connections. Thread the inlet line (from tank) into the pump inlet port and tighten with a fuel line wrench while supporting the pump body with a backup wrench. Tighten to 18-22 ft-lbs. Repeat for the outlet line (to carburetor). Do not overtighten as this can strip the brass fittings or crack the pump body.
11. 11

    Prime fuel pump
    Before starting the engine, manually prime the fuel system. With the fuel lines connected but battery still disconnected, rotate the engine crankshaft by hand several complete revolutions. This cycles the fuel pump pushrod and begins moving fuel through the system. Check all connections for leaks during this process.
12. 12

    Perform leak check
    Reconnect the negative battery cable. Turn the ignition key to the ON position without starting the engine (if equipped with electric fuel accessories). Visually inspect all fuel pump connections and the pump body gasket for any signs of fuel seepage. Have an assistant crank the engine for 10-15 seconds without starting it (disable ignition or pull coil wire) to build fuel pressure. Inspect again for leaks. Any fuel seepage requires immediate correction before engine start.

Reassembly

1. Ensure both fuel lines are securely tightened with backup wrenches to prevent pump body stress
2. Verify fuel pump mounting bolts are torqued evenly to prevent gasket distortion
3. Confirm pushrod is properly seated and has not fallen into engine during installation
4. Double-check that all shop rags have been removed from fuel lines and engine compartment

Verification

• Start engine and allow to idle for 2-3 minutes while monitoring fuel pump and all connections for leaks
• Inspect fuel pump mounting gasket area for any fuel or oil seepage while engine is running
• Rev engine to 2000-2500 RPM and verify smooth operation with no fuel starvation or hesitation
• Check fuel pump for unusual noise (clicking, grinding, or squealing indicates internal failure or improper pushrod engagement)
• Verify fuel pressure at carburetor is within specification (4-6 psi for stock 327ci applications) using a fuel pressure gauge if available
• After initial test run, shut off engine and perform final visual inspection of all connections after fuel system pressure stabilizes

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