GM Service Manual Online
For 1990-2009 cars only

Tools Required

    • J 26900-2 Outside Micrometer
    • J 8001 Dial Indicator Set
    • J 26900-13 Magnetic Indicator Base
  1. Inspect the valve lifters for scoring where they contact the camshaft.

  2. Object Number: 188095  Size: SH
  3. Inspect the camshaft journals and lobes for wear or scoring (1, 2).
  4. Wash the cylinder head in solvent.
  5. Inspect the cylinder head for cracks or other signs of damage.
  6. Inspect the cylinder head for scoring in the lifter lobes.
  7. Inspect the camshaft bearing caps for wear, cracks and scoring.
  8. Inspect the camshaft bearing journals in the cylinder head for wear, cracks and scoring.
  9. If excessive wear or scoring is present, or if the cylinder head is cracked, replace the cylinder head (with bearing caps).

  10. Object Number: 262331  Size: SH
  11. Measure the camshaft lobe height using the J 26900-2 . Replace the camshaft if any lobe is below the minimum.
  12. Standard Intake Camshaft Lobe Height
    44.333-44.433 mm (1.7454-1.7493 in)

    Minimum Intake Camshaft Lobe Height
    44.18 mm (1.7394 in)

    Standard Exhaust Camshaft Lobe Height
    43.761-43.861 mm (1.7229-1.7268 in)

    Minimum Exhaust Camshaft Lobe Height
    43.61 mm (1.7169 in)


    Object Number: 166364  Size: SH
  13. Place the camshaft (1) onto V-blocks. Measure the camshaft runout using the J 8001 with the J 26900-13 . Replace the camshaft if the runout exceeds specifications.
  14. Camshaft Runout
    0.03 mm (0.0012 in)

  15. Clean the journals of the camshaft and the cylinder head.
  16. Do not install the valve lifters.

  17. Object Number: 427004  Size: SH
  18. Install the camshafts.
  19. Important: Do not turn the camshafts while the gauging plastic is installed.

  20. Place a piece of gauging plastic across the full width of each camshaft journal.
  21. Important: Cylinder head and camshaft damage may result if the bearing caps are incorrectly installed. The oil clearance measurement will also be incorrect.

  22. Install the camshaft bearing caps in their original locations.
  23. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  24. Use 3 progressive steps to tighten the camshaft bearing cap bolts in sequence.
  25. Tighten
    Tighten the bolts to 13 N·m (10 lb ft).

    Tighten
    Tighten the front bolts to 23 N·m (17 lb ft).

  26. Remove the camshaft bearing caps.
  27. Measure the gauging plastic at its widest point.
  28. Standard Oil Clearance
    0.035-0.072 mm (0.0014-0.0028 in)

    Maximum Oil Clearance
    0.10 mm (0.0039 in)

  29. If the oil clearance is greater than the maximum, replace the camshaft. If necessary, replace the cylinder head with caps as a set.
  30. Install the camshafts.
  31. Using the J 8001 , measure the thrust clearance while moving the camshaft back and forth.
  32. Standard Thrust Clearance
    0.040-0.095 mm (0.0016-0.0037 in)

    Maximum Thrust Clearance
    0.11 mm (0.0043 in)

  33. If the thrust clearance is greater than maximum, replace the camshaft. If necessary, replace the bearing caps and cylinder head as a set.