Valve Lash Adjustment: Notes

Tools Required 

J 26900-1  Outside Micrometer

Important: 

• Valve clearance measurement should only be done on a cold engine.
• To change the valve clearance on a given valve, the lifter must be replaced by one that is thicker or thinner in size.
• Lifters are available in 35 different sizes, in increments of 0.020 mm (0.0008 in).
• Lifters range in size from 5.060 mm (0.1992 in) to 5.740 mm (0.2260 in).

1. Disconnect the negative battery cable.
2. Remove the cylinder head cover. Refer to CYLINDER HEAD COVER REPLACEMENT  .
3. Turn the crankshaft clockwise until the alignment notch on the crankshaft pulley is aligned with the "0" mark on the engine front cover tab.
   Fig 1: Identifying Alignment Notch

   Courtesy of GENERAL MOTORS CORP.
4. Check that the point marks on the camshaft gears are aligned. If the point marks on the camshaft gears are not aligned, turn the crankshaft clockwise one revolution in order to align the camshaft gears.
   Fig 2: Aligning Point Marks On Camshaft Gears

   Courtesy of GENERAL MOTORS CORP.
5. Using a feeler gage, measure the clearance between the intake valve lifters and the intake camshaft for cylinders #1, and #2.
   Fig 3: Locating Valve Lifters And Camshaft For Cylinders 1, 2 & 3

   Courtesy of GENERAL MOTORS CORP.

   Intake Valve Clearance (Cold): 

   0.15-0.25 mm (0.006-0.010 in)

   Important:  Record any out of specification valve clearance measurements. The measurements will be used later to determine the required replacement lifter.

6. Using a feeler gage, measure the clearance between the exhaust valve lifters and the exhaust camshaft for cylinders #1, and #3.

   Exhaust Valve Clearance (Cold): 

   0.25-0.35 mm (0.010-0.014 in)

   Important:  Record any out of specification valve clearance measurements. The measurements will be used later to determine the required replacement lifter.

7. Turn the crankshaft clockwise 1 revolution until the alignment notch on the crankshaft pulley is aligned with the "0" mark on the engine front cover tab.
8. Using a feeler gage, measure the clearance between the intake valve lifters and the intake camshaft for cylinders #3, and #4.

   Intake Valve Clearance (Cold): 

   0.15-0.25 mm (0.006-0.010 in)

   Important:  Record any out of specification valve clearance measurements. The measurements will be used later to determine the required replacement lifter.

   Fig 4: Locating Valve Lifters And Camshaft For Cylinders 2, 3 & 4

   Courtesy of GENERAL MOTORS CORP.
9. Using a feeler gage, measure the clearance between the exhaust valve lifters and the exhaust camshaft for cylinders #2, and #4.

   Exhaust Valve Clearance (Cold): 

   0.25-0.35 mm (0.010-0.014 in)

   Important:  Record any out of specification valve clearance measurements. The measurements will be used later to determine the required replacement lifter.

10. If there were any valve clearances that were out of specifications, the camshaft(s) must be removed in order to replace the lifter(s). To remove the intake camshaft, refer to INTAKE CAMSHAFT AND LIFTER REPLACEMENT   or to remove the exhaust camshaft, refer to EXHAUST CAMSHAFT AND LIFTER REPLACEMENT   .