Remove and replace all eight spark plugs on the 327ci V8 engine, applying anti-seize compound and torquing to specification for cast iron cylinder heads.

Warnings

Tools required

Parts

• Spark plugs × 8 — AC Delco R44 or equivalent (0.035" gap)
• Anti-seize compound × 1 — Nickel-based anti-seize

Preparation

1. Ensure engine is completely cold to the touch
2. Park vehicle on level surface and engage parking brake
3. Open hood and secure with prop rod
4. Identify all eight spark plug locations (four per cylinder bank)
5. Label spark plug wires 1-8 if not already marked to ensure correct firing order reassembly

Procedure

1. 1

   Remove spark plug wires from driver side bank
   Starting with cylinders 1, 3, 5, and 7 on the driver side, grasp each spark plug wire boot firmly at the base where it connects to the spark plug. Twist the boot gently back and forth while pulling straight away from the plug to break the seal. Never pull on the wire itself as this can damage the conductor. Remove all four wires from this bank.
2. 2

   Clean spark plug wells on driver side
   Use compressed air to blow out any debris, dirt, or oil from around each of the four exposed spark plugs on the driver side. If compressed air is not available, use a clean rag. This prevents contamination from falling into the cylinders when plugs are removed.
3. 3

   Remove driver side spark plugs
   Using the 5/8" spark plug socket with extension and ratchet, loosen each of the four spark plugs on the driver side by turning counterclockwise. Once loose, remove plugs by hand to prevent dropping them. Inspect each plug for fouling, oil deposits, or unusual wear patterns that might indicate engine issues.
   Torque spec

   Spark Plugs - Cast Iron Head30 Nm (22 lb-ft)
4. 4

   Prepare new spark plugs for driver side
   Verify the gap on four new spark plugs using the gap tool; correct gap should be 0.035". Adjust if necessary by gently bending the ground electrode. Apply a thin coat of anti-seize compound to the threads of each plug, keeping anti-seize away from the electrode and at least two threads back from the plug face to prevent contamination of the combustion chamber.
   Torque spec

   Spark Plugs - Cast Iron Head30 Nm (22 lb-ft)
5. 5

   Install driver side spark plugs
   Thread each new spark plug into its cylinder by hand, turning clockwise. This ensures you do not cross-thread. Once finger-tight, use the torque wrench with spark plug socket to tighten each plug to approximately 25 lb-ft (34 Nm), reducing torque by about 15-20% to account for the anti-seize on the threads. Do not over-torque.
   Torque spec

   Spark Plugs - Cast Iron Head30 Nm (22 lb-ft)
6. 6

   Reconnect driver side spark plug wires
   Press each spark plug wire boot firmly onto its corresponding spark plug until the terminal is fully seated over the plug, then give the wire a gentle tug to confirm it is secure. Ensure wires are routed away from exhaust manifolds and moving components. Verify correct cylinder numbering: on the driver side, front to rear is cylinders 1, 3, 5, 7.
7. 7

   Remove spark plug wires from passenger side bank
   Repeat the wire removal process for cylinders 2, 4, 6, and 8 on the passenger side. Grasp each boot at the base, twist gently, and pull straight away from the plug. Remove all four wires from this bank.
8. 8

   Clean spark plug wells on passenger side
   Use compressed air or a clean rag to remove all debris from around each of the four spark plug locations on the passenger side before removing the plugs.
9. 9

   Remove passenger side spark plugs
   Using the 5/8" spark plug socket with extension and ratchet, loosen and remove each of the four spark plugs on the passenger side by turning counterclockwise. Inspect plugs for condition and compare wear patterns to the driver side plugs.
   Torque spec

   Spark Plugs - Cast Iron Head30 Nm (22 lb-ft)
10. 10

    Prepare new spark plugs for passenger side
    Verify gap on the remaining four new spark plugs at 0.035". Apply anti-seize compound to threads as before, keeping compound away from the electrode area and at least two threads back from the plug face.
    Torque spec

    Spark Plugs - Cast Iron Head30 Nm (22 lb-ft)
11. 11

    Install passenger side spark plugs
    Thread each new spark plug by hand into its cylinder, ensuring proper engagement without cross-threading. Torque each plug to exactly 30 Nm (22 lb-ft) using the torque wrench and spark plug socket.
    Torque spec

    Spark Plugs - Cast Iron Head30 Nm (22 lb-ft)
12. 12

    Reconnect passenger side spark plug wires
    Press each spark plug wire boot firmly onto its corresponding spark plug until it clicks into place. Verify correct cylinder numbering: on the passenger side, front to rear is cylinders 2, 4, 6, 8. Ensure all wires are properly routed and secured away from heat and moving parts.

Reassembly

1. Double-check that all eight spark plug wire boots are fully seated on their plugs
2. Verify all wires are routed properly and not touching exhaust manifolds or other heat sources
3. Ensure no tools or parts are left in the engine bay

Verification

• Start the engine and listen for smooth idle with no misfiring or rough running
• Verify no spark plug wires are arcing (visible sparks jumping to ground) in darkness
• Check that engine accelerates smoothly without hesitation
• Inspect around spark plugs for any vacuum leaks or hissing sounds indicating improper sealing

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