Valve Timing: Checking
- Measure valve timing at intake valves No. 1 and 6. Remove valve covers. Rotate crankshaft in direction of engine rotation until lobes of intake cams being tested are facing up (only base circles resting on hydraulic lifters).
- Attach a dial indicator with tip resting vertically on cylinder No. 1 intake valve hydraulic lifter. Preload dial indicator .12" (3 mm) and zero dial. Ensure tip moves freely. Rotate crankshaft in direction of engine rotation until dial indicator reads .08" (2 mm) valve lift.
- With .08" (2 mm) intake valve lift (valve opening), crankshaft should indicate specification in VALVE TIMING SPECIFICATIONS table. Continue rotating crankshaft until intake valve starts closing. Crankshaft should indicate specification in VALVE TIMING SPECIFICATIONS table. Repeat steps 2) and 3) for cylinder No. 6 intake valve.
- Attach a dial indicator so tip is resting vertically on cylinder No. 1 exhaust valve hydraulic lifter. Preload dial indicator .12" (3 mm) and zero dial. Ensure tracer pin moves freely. Rotate crankshaft in direction of engine rotation until dial indicator reads .08" (2 mm) valve lift.
- With .08" (2 mm) exhaust valve lift (valve opening), crankshaft should indicate specification in VALVE TIMING SPECIFICATIONS table. Continue rotating crankshaft until exhaust valve starts closing. Crankshaft should indicate specification in VALVE TIMING SPECIFICATIONS table. Repeat steps 4) and 5) for cylinder No. 6 exhaust valve.
- If valve timing is not to specification, ensure hydraulic lifters are functioning properly. Replace hydraulic lifters as necessary. If hydraulic lifters are okay, check timing chain for excessive stretching. Replace timing chain if necessary.
VALVE TIMING SPECIFICATIONS
| Engine |
Crankshaft Degrees |
| Intake Valve Opens |
30° ATDC |
| Intake Valve Closes |
40° ABDC |
| Exhaust Valve Opens |
13° BBDC |
| Exhaust Valve Closes |
13° BTDC |