Removal & Installation: Camshaft: Inspection

1. Inspect rocker arms and shaft for wear. Determine rocker arm-to-shaft clearance. Rocker arm I.D. should measure .629-.630" (15.98-16.0 mm). Rocker shaft diameter is .628-.629" (15.95-15.98 mm).
2. Standard clearance is .0005-.0017" (.013-.043 mm). Maximum clearance is .0035" (.089 mm). If specifications are exceeded, replace rocker shaft or arm. Mount rocker shaft in "V" blocks. Measure rocker shaft runout using a dial indicator. Maximum runout is .004" (.10 mm). Replace shaft if specifications are exceeded.
3. Measure cam lobe height using a micrometer. If height is less than specifications, replace camshaft. Mount camshaft in "V" blocks and measure runout. Maximum runout is .0039" (.01 mm).
   CAMSHAFT LOBE HEIGHT
   
   

   Application	In. (mm)
   Intake Lobe	(1) 1.501 (38.13)
   Exhaust Lobe	(1) 1.501 (38.13)
   Fuel Pump Drive Lobe	(2) 1.575 (40.00)
   (1) Wear limit is 1.497" (38.03 mm). (2) Wear limit is 1.559" (39.60 mm).

4. Inspect camshaft journals for wear and damage. Measure journal shaft diameter and journal bore diameter to determine journal clearance. See Fig 1. Journal clearance should measure .002-.0036" (.05-.09 mm). If journal clearance exceeds .006" (.15 mm), replace camshaft and/or cylinder head.

Fig 1: Camshaft Journal Identification

Courtesy of GENERAL MOTORS CORP.