Adjusting Valve Clearance

How to Adjust Valve Clearance on a Honda S2000

Introduction

Adjusting the valve clearance (or valve lash) on a Honda S2000 is an essential maintenance task that ensures optimal engine performance and longevity. The S2000's F20C and F22C1 engines are high-revving powerplants that demand precise maintenance to operate smoothly. This guide will walk you through the process of checking and adjusting the valve clearance, a task recommended every 40,000 to 60,000 kilometers (25,000 to 37,000 miles) or if you notice unusual engine noise.

Tools and Materials Needed

• Feeler gauge set
• 10mm and 14mm socket and ratchet
• Torque wrench
• Flathead screwdriver
• Valve cover gasket set (recommended for replacement)
• Permatex or similar RTV silicone sealant
• Honda Bond (for sealing camshaft end caps)
• Clean rags
• Brake cleaner or degreaser
• Service manual for torque specifications

Safety Precautions

• Work on a cool engine: The engine should be completely cooled down before starting this procedure to avoid burns and ensure accurate measurements.
• Disconnect the battery: Disconnect the negative battery terminal to prevent accidental starts while working on the engine.

Step-by-Step Guide

1. Preparation

1. Park the car on a level surface and engage the parking brake.
2. Open the hood and disconnect the negative battery terminal.
3. Remove the engine cover: If your S2000 has the OEM plastic engine cover, remove it by unscrewing the bolts and lifting it off.

2. Remove the Valve Cover

1. Unplug the ignition coils: Disconnect the electrical connectors from the ignition coils and remove the coils by unscrewing the bolts that hold them in place.
2. Remove the valve cover bolts: Use a 10mm socket to remove all the valve cover bolts. Keep track of the different bolt lengths and positions.
3. Lift the valve cover off: Gently lift the valve cover off, being careful not to damage the gasket. You may need to tap it lightly with a rubber mallet if it's stuck. Set the valve cover aside.

3. Rotate the Engine to Top Dead Center (TDC)

1. Locate the crankshaft pulley: Use a 19mm socket on the crankshaft pulley bolt to rotate the engine clockwise.
2. Set the engine to TDC for cylinder 1: Rotate the crankshaft until the “UP” mark on the camshaft gear is facing up and the two parallel lines on the camshaft gears are aligned with the cylinder head surface. This indicates that cylinder 1 is at TDC on the compression stroke.

4. Check Valve Clearance

1. Refer to the service manual for the correct clearance: For the F20C and F22C1 engines, the valve clearance should be
   1. Intake: 0.21–0.25 mm (0.008–0.010 inches),
   2. Exhaust: 0.28–0.32 mm (0.011–0.013 inches).
2. Insert the feeler gauge: Slide the appropriate feeler gauge between the camshaft and the rocker arm for each valve. There should be a slight drag on the gauge when the clearance is correct.
3. Record the measurements: Check and record the clearance for each valve. Note any valves that are out of specification.

5. Adjust Valve Clearance

1. Loosen the lock nut: If a valve needs adjustment, use a 10mm wrench to loosen the lock nut on the rocker arm.
2. Adjust the clearance: Turn the adjustment screw with a flathead screwdriver to achieve the correct clearance. Hold the adjustment screw in place and tighten the lock nut. Recheck the clearance to ensure it didn’t change during tightening.
3. Repeat for all valves: Rotate the crankshaft 180 degrees clockwise to move to the next cylinder in the firing order (1-3-4-2). Repeat the checking and adjusting process for all valves.

6. Reassemble the Engine

1. Clean the valve cover: Remove any old gasket material and apply a thin layer of Honda Bond to the camshaft end caps.
2. Install a new valve cover gasket: If the old gasket is damaged or worn, replace it with a new one. Place the valve cover back onto the cylinder head.
3. Torque the valve cover bolts: Reinstall the valve cover bolts and tighten them to the specified torque in a crisscross pattern to ensure even pressure.
4. Reinstall the ignition coils and reconnect the electrical connectors.
5. Reconnect the battery and start the engine to check for any leaks or unusual noises.

7. Final Checks

• Listen for valve noise: After reassembly, start the engine and listen for any abnormal ticking or knocking sounds, which could indicate that the valve clearances need further adjustment.
• Test drive: Take the car for a short drive to ensure everything is functioning correctly.

Conclusion

Adjusting the valve clearance on your Honda S2000 is a vital maintenance task that can prevent engine damage and maintain performance. By following this guide, you can confidently perform this procedure yourself, ensuring your S2000 continues to run smoothly.