Valve Cover Gasket - Single

This procedure removes and replaces the valve cover gasket on one cylinder bank of the 1966 Chevrolet Corvette 327ci V8 to eliminate oil leaks.

Warnings

Tools required

Parts

• Valve cover gasket (cork or rubber) × 1 — Use OEM specification
• Valve cover bolt grommets (if equipped) × 6 — Use OEM specification

Preparation

1. Park vehicle on level ground and set parking brake.
2. Allow engine to cool completely to ambient temperature.
3. Disconnect negative battery cable to prevent accidental starter engagement.
4. Gather all tools and new gasket materials before beginning work.

Procedure

1. 1

   Remove air cleaner assembly
   Remove the wing nut securing the air cleaner lid. Lift off the air cleaner lid and set aside. Remove the air cleaner element. Remove the air cleaner base mounting hardware (typically 1 center stud nut) and lift the air cleaner base off the carburetor. Disconnect any breather hoses attached to the valve cover.
2. 2

   Disconnect spark plug wires
   Label or photograph the spark plug wire routing for correct reassembly. Grasp each spark plug wire boot firmly at the base near the spark plug and twist while pulling to remove. Do not pull on the wire itself. Remove wires from cylinders on the valve cover being serviced (4 wires total).
3. 3

   Remove PCV valve or breather components
   If a PCV valve is fitted to the valve cover grommet, disconnect it by pulling firmly. Note that on some 1966 327 configurations the crankcase ventilation valve is located at the intake/carburetor base rather than the valve cover. If working on the passenger side, remove any breather cap or oil filler tube attached to the valve cover. Set components aside.
4. 4

   Remove valve cover mounting bolts
   Using a 3/8" socket, remove the 4 valve cover mounting bolts in a crisscross pattern starting from the outer bolts and working inward. Keep the bolts and any grommets or washers organized for reinstallation. Note the condition of any rubber grommets.
5. 5

   Remove valve cover
   Carefully lift the valve cover straight up off the cylinder head. If the cover is stuck due to old gasket material, gently tap the sides with a rubber mallet or carefully pry at a reinforced corner using a plastic scraper. Do not pry against the sealing surface of the cover or head. Once free, remove the cover and set it on a clean work surface.
6. 6

   Remove old gasket material
   Remove all old gasket material from both the valve cover sealing surface and the cylinder head sealing surface. Use a plastic or brass scraper to avoid scratching or gouging the metal surfaces. Remove all traces of old cork, rubber, or sealant. Use a wire brush carefully on stubborn areas, then wipe both surfaces clean with brake cleaner and clean rags. Inspect both sealing surfaces for warping or damage.
7. 7

   Inspect internal components
   With the valve cover removed, visually inspect the rocker arms, pushrods, and valve springs for obvious wear or damage. Check for broken valve springs or bent pushrods. This is a good opportunity to verify proper rocker arm geometry and adjustment if needed, though full adjustment is beyond the scope of this gasket replacement.
8. 8

   Clean valve cover exterior and interior
   Thoroughly clean the valve cover inside and out using brake cleaner and shop rags. Remove all oil residue, dirt, and old gasket material. Ensure the bolt holes are clean and free of debris. Dry the cover completely.
9. 9

   Install new valve cover gasket
   Position the new gasket onto the valve cover flange. Cork gaskets may benefit from a thin bead of RTV silicone on both sides to aid in sealing and retention, though this is optional. If using rubber gaskets with integrated grommets, ensure the gasket is properly seated in the cover groove all the way around. Verify the gasket is not twisted and all bolt holes align properly.
10. 10

    Reinstall valve cover to cylinder head
    Carefully position the valve cover with installed gasket back onto the cylinder head. Ensure the gasket remains properly seated and aligned with all bolt holes. The cover should sit flat without forcing. Insert all 4 valve cover bolts with any grommets or washers finger-tight.
11. 11

    Torque valve cover bolts to specification
    Using a torque wrench, tighten the valve cover bolts to specification in a crisscross pattern starting from the center bolts and working outward. Tighten in two stages: first snug all bolts evenly, then to the final specification of approximately 3-5 lb-ft for stamped-steel covers with cork gaskets. Do not overtighten, as excessive torque crushes the cork and causes leaks. This ensures even gasket compression and prevents leaks.
    Torque spec

    Valve Cover Bolts10 Nm (7 lb-ft)
12. 12

    Reinstall PCV valve or breather components
    Reinstall the PCV valve into the valve cover grommet on the driver side, or reinstall the breather cap or oil filler tube on the passenger side. Ensure all fittings are secure and properly seated.
13. 13

    Reconnect spark plug wires
    Reconnect the spark plug wires to their respective spark plugs according to your labeling or photograph. Push each boot firmly onto the spark plug until it clicks or seats fully. Verify correct firing order routing.
14. 14

    Reinstall air cleaner assembly
    Position the air cleaner base back onto the carburetor and secure with the mounting hardware. Install the air cleaner element, then install the air cleaner lid and secure with the wing nut. Reconnect any breather hoses to the valve cover.
15. 15

    Reconnect battery and perform final checks
    Reconnect the negative battery cable. Before starting the engine, perform a final visual inspection of all connections, ensuring no tools or rags are left in the engine bay.

Reassembly

1. Torque all valve cover bolts in a crisscross pattern to ensure even gasket compression.
2. Verify all spark plug wires are routed correctly and fully seated to prevent misfires.
3. Ensure PCV valve and breather components are properly installed to maintain correct crankcase ventilation.

Verification

• Start the engine and allow it to idle for 2-3 minutes while observing the valve cover area for any oil leaks.
• Check for proper oil sealing around the entire valve cover perimeter, particularly at the corners and bolt locations.
• Listen for any unusual valve train noise that might indicate improper reassembly.
• After a short test drive, recheck the valve cover area for leaks with the engine warmed up.
• Verify engine idles smoothly with no misfires from improperly seated spark plug wires.

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