GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 8520 Camshaft Lobe Lift Indicator

  1. Remove the valve rocker arm. Refer to Valve Rocker Arm and Push Rod Replacement .

  2. Object Number: 4579  Size: SH
  3. Position the dial indicator (part of the J 8520 ) so the plunger rests on the pushrod end, as shown. Make sure the pushrod is in the valve lifter socket.
  4. Rotate the crankshaft slowly in the direction of normal rotation until the valve lifter is on the heel of the cam lobe. At this point, the pushrod will be in its lowest position.
  5. Important: Whenever the engine is cranked remotely at the starter, the distributor primary lead or coil primary leads must be disconnected.

  6. Set the dial indicator on zero, then rotate the crankshaft slowly, or attach an auxiliary starter switch and "bump" the engine over until the pushrod is in the fully raised position.
  7. Compare the total lift recorded from the dial indicator with specifications. Refer to Camshaft in 5.0L/5.7L Engine Specifications.
  8. If the camshaft readings for all lobes are within specifications, remove the dial indicator assembly.
  9. Install the valve rocker arm. Refer to Valve Rocker Arm and Push Rod Replacement .
  10. Adjust the valves. Refer to Valve Lash Adjustment .