1. Ensure that the engine is cold.
2. Remove the spark plug wires and spark plugs.
3. Remove the valve cover.
4. Using a feeler gauge, set the tappets to the correct clearances:
- Intake tappet clearance: 0.2 - 0.3mm
- Exhaust tappet clearance: 0.3 - 0.4mm
5. Tighten the tappet adjusters until the feeler gauge just starts to drag when pulled through.
6. Reinstall the spark plugs and spark plug wires.
7. Replace the valve cover.
8. Start the engine and check for proper operation.