Valve Clearance: Adjustments

TO ADJUST VALVE CLEARANCE:

- Valve clearance should be measured with the engine warm. Coolant temperature should be at least 35°C (95°F) or the engine should be at least warm to the touch. The clearance changes with engine temperature, so more precise adjustment is possible when the engine is warm. Because it may be necessary to adjust the valves when the engine is cold, such as after cylinder head repairs, specifications for both hot and cold engines are given.

1. Remove the cylinder head cover.
2. Using a socket wrench on the crankshaft vibration damper bolt, hand-turn the crankshaft clockwise until both the No. 1 cylinder's cam lobes are pointing approximately upward (valves fully closed).

NOTE: No. 1 cylinder is the one closest to the camshaft drive belt.

Cylinder Head Cross-Section:

Checking Valve Clearance:

3. Measure the valve clearances. Insert feeler gauges between the cam lobe and the adjusting disc on the top of the cam follower. Compare the measured clearance values with the specifications given below.

Valve Clearance Specifications:
Engine Warm:
Intake: 0.20-0.30 mm (0.008-0.012 in.)
Exhaust: 0.40-0.50 mm (0.O16-0.02O in.)
Engine Cold:
Intake: 0.15-0.25 mm (0.006-0.010 in.)
Exhaust: 0.35-0.45 mm (0.O14-0.O18 in.)

Removing Adjusting Disc:

4. If valve clearance is not within the specifications, replace the adjusting disc. Depress the cam follower and lift out the disc as shown.

NOTE: To calculate the correct adjusting disc thickness, first determine the thickness of the old disc. Read the thickness in millimeters that is etched on its underside, or measure it with a micrometer. The change in thickness required is the same as the difference between the measured clearance and the specification given above. A thicker disc will reduce valve clearance. A thinner disc will increase valve clearance.

5. Install the correct adjusting disc. Lightly oil the contact surfaces. Depress the cam follower and install the disc the same way it was removed. The etched disc thickness numbers should face down.
6. Using a socket wrench, rotate the crankshaft clockwise by hand for two complete turns, to ensure that the adjusting disc is properly seated, and recheck the clearance.
7. Rotate the crankshaft by hand clockwise until the cam lobes for the next cylinder to be checked point up and away from the followers and repeat the procedure on the valves for this cylinder. Procede in order through the remain cylinders.
8. Install the cylinder head cover with new gaskets.