Remove valve cover. Rotate engine until zero degree (TDC) timing mark of timing belt cover is in line with timing mark on crankshaft pulley.
Ensure cylinder No. 1 is at TDC on compression stroke. Remove distributor cap. Ensure rotor is pointed upward at distributor hold-down bolt and to No. 1 terminal of distributor cap.
Check the intake valve clearance of cylinders No. 1 and 2 and the exhaust valve clearance of cylinders No. 1 and 3. See the VALVE CLEARANCE SPECIFICATIONS table.
Turn crankshaft one complete revolution (360 degrees). Check intake valve clearance of cylinders No. 3 and 4 and exhaust valve clearance of cylinders No. 2 and 4.
Measure valve clearance between adjustment screw and valve stem using feeler gauge. Adjust valves by loosening lock nut and turning adjusting screw until clearance is as specified. After adjusting clearance, tighten adjusting screw lock nut to 11.0-13.5 ft. lbs. (15-18 N.m). Recheck clearance.

Fig 1: Locating Ignition Timing Mark (Typical)

Courtesy of GENERAL MOTORS CORP.

VALVE CLEARANCE SPECIFICATIONS

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Valve Clearance