GM Service Manual Online
For 1990-2009 cars only

Tools Required

    • J 7872 Magnetic Base Dial Indicator
    • SA9179NE Dial Indicator

Camshaft Inspection


    Object Number: 897293  Size: SH
  1. Clean the camshaft and inspect for pitted, scored or excessively worn lobes.
  2. Measure the diameter of each bearing journal.

  3. Object Number: 897120  Size: SH

    Important: In order to properly measure the camshaft journal bores, the rocker arm shafts must be bolted to the cylinder heads.

  4. Remove the rocker arms (215, 218) and springs (219) from the shafts (220, 221).
  5. Lubricate the bolt threads and flanges with clean engine oil.
  6. Install the rocker arm shafts and bolts to the cylinder heads.
  7. Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 897290  Size: SH
  8. Tighten the left cylinder head rocker shaft bolts in sequence.
  9. Tighten

    1. Tighten the bolts a first pass to 12 N·m (106 lb in).
    2. Tighten the bolts a final pass to 24 N·m (17 lb ft).

    Object Number: 1308159  Size: SH
  10. Tighten the right cylinder head rocker shaft bolts in sequence.
  11. Tighten

    1. Tighten the bolts a first pass to 12 N·m (106 lb in).
    2. Tighten the bolts a final pass to 24 N·m (17 lb ft).

    Object Number: 897295  Size: SH
  12. Clean the bearing surfaces in the cylinder head and measure the inside diameter (ID) of each camshaft bearing surface. Also, inspect for an out-of-round condition.
  13. Calculate the camshaft-to-journal clearance.
  14. Specification

        • Camshaft-to-journal clearance - new: 0.05-0.2 mm (0.002-0.008 in)
        • Camshaft-to-journal clearance - service limit: 0.2 mm (0.008 in)

    Object Number: 897298  Size: SH
  15. Install the camshaft into V-blocks and use the J 7872 to measure the runout.
  16. Specification

        • Camshaft total runout - new: 0.03 mm (0.001 in)
        • Camshaft total runout - service limit: 0.04 mm (0.002 in)

    Object Number: 897300  Size: SH
  17. Identify the camshaft lobes.
  18. • Exhaust (1)
    • Intake primary - right cylinder head (2)
    • Intake mid (3)
    • Intake secondary - right cylinder head (4)
    • Intake secondary - left cylinder head (5)
    • Intake primary - left cylinder head (6)
  19. Measure the camshaft lobe height. If the measurement is less than the specification, replace the camshaft.
  20. Specification

        • Intake primary lobe height: 35.041 mm (1.3796 in)
        • Intake mid lobe height: 36.445 mm (1.4348 in)
        • Intake secondary lobe height: 35.284 mm (1.3891 in)
        • Exhaust lobe height: 36.326 mm (1.4302 in)

Measuring Camshaft End Play


    Object Number: 897120  Size: SH

    Important: In order to properly measure camshaft end play, the rocker arm shafts must be bolted to the cylinder heads.

  1. Remove the rocker arms (215 and 218) and springs (219) from the shafts (220 and 221).
  2. Lubricate the bolt (214) threads and flanges with clean engine oil.
  3. Install the rocker arm shafts (220, 221) and bolts (214) to the cylinder heads.

  4. Object Number: 897290  Size: SH
  5. Tighten the left cylinder head rocker shaft bolts in sequence.
  6. Tighten

    1. Tighten the bolts a first pass to 12 N·m (106 lb in).
    2. Tighten the bolts a final pass to 24 N·m (17 lb ft).

    Object Number: 1308159  Size: SH
  7. Tighten the right cylinder head rocker shaft bolts in sequence.
  8. Tighten

    1. Tighten the bolts a first pass to 12 N·m (106 lb in).
    2. Tighten the bolts a final pass to 24 N·m (17 lb ft).

    Object Number: 897133  Size: SH
  9. Install the camshafts (209), caps (211), and bolts (212).
  10. Tighten
    Tighten the bolts to 22 N·m (16 lb ft).


    Object Number: 897291  Size: SH
  11. Seat the camshaft by pushing it toward the rear of the cylinder head.
  12. Use the SA9179NE in order to measure the end play. Zero the dial indicator against the end of the camshaft. Push the camshaft forward and rearward and measure the end play.
  13. Specification

        • Camshaft end play - new: 0.05-0.2 mm (0.002-0.008 in)
        • Camshaft end play - service limit: 0.2 mm (0.008 in)