Valve Rocker Arm and Shaft Replacement

REMOVAL PROCEDURE

^ TOOLS REQUIRED
- J 41040 Camshaft Sprocket Spanner Wrench
- J 8001 Dial Indicator Set
- J 26900-13 Magnetic Base
- J 26900-1 Outside Micrometer

CAUTION: Refer to Battery Disconnect Caution in Service Precautions.

1. Disconnect the negative battery cable.
2. Remove the front grille from the vehicle.
3. Remove the two bolts and the hood latch from the front end panel.
4. Remove the two electrical connectors from the horn.





5. Remove the twelve bolts and the front end panel (1) from the vehicle.
6. Remove the radiator from the radiator core support.
7. Remove the timing belt from the engine.
8. Use the J 41040 in order to hold the camshaft timing belt gear stationary. Remove one bolt and the camshaft timing belt gear from the camshaft.
9. Remove the cylinder head cover from the cylinder head.

IMPORTANT: A small amount of oil may drain from the distributor case upon removal from the cylinder head. Place a suitable container underneath the case or use a shop towel to catch and absorb oil.

10. Remove the distributor from the distributor case.





11. Remove the three bolts and the distributor case (1) from the cylinder head.





12. Loosen all valve adjusting screw locknuts (3).
13. Loosen all valve adjusting screws (2) until all rocker arms (1) move freely.

NOTICE: Always remove the camshaft carrier bolts gradually in the order specified in order to relieve the tension on the camshaft. If the camshaft carrier bolts are removed at random, damage to the camshaft may occur.





14. Remove the following from the cylinder head:
^ Twelve bolts
^ The camshaft carrier caps (1)
^ The camshaft seal
^ The camshaft





15. Remove the rocker arm shaft plug (1) from the cylinder head.
16. Remove the two bolts and the timing belt inside cover from the cylinder head.
17. Remove all of the intake rocker arms with clips from the rocker arm shaft.





18. Remove the six rocker arm shaft bolts (1) from the cylinder head.
19. Push the rocker arm shaft (2) back through the rear of the cylinder head until the end of the rocker arm shaft appears.





20. Remove the O-ring (2) from the rear of the rocker arm shaft (1).
21. Remove the following components by pulling the rocker arm shaft through the front of the cylinder head:
^ The exhaust rocker arms
^ The rocker arm springs
^ The rocker arm shaft

22. Clean all of the camshaft and rocker arm components thoroughly with clean solvent.





23. Inspect the rocker arms (2, 5) for excessive wear or damage. Pay particular attention to the rocker arm adjusting screw tips (4, 7) and cam riding surfaces. If excessive wear or damage exists, replace the rocker arms as necessary.
24. Inspect the following for excessive wear or damage:
^ The camshaft
^ The camshaft carrier
^ The carrier caps

Replace the components as necessary.





25. Use a J 8001 with a J 26900-13 in order to measure the rocker arm shaft (1) runout.
1. Place the rocker arm shaft (1) between two V-blocks and rotate slowly while measuring the runout. The maximum rocker-arm shaft runout is 0.20 mm (0.008 in).
2. Replace the rocker arm shaft if the rocker arm shaft runout exceeds 0.20 mm (0.008 in).





26. Use the J 26900-1 and a telescopic micrometer in order to measure the rocker arm-to-rocker arm shaft clearance.
1. Use the J 26900-1 in order to measure the outside diameter of the rocker arm shaft (1). The standard rocker arm outside diameter 15.969 to 15.984 mm (0.6287 to 0.6293 in).
2. Use a telescopic micrometer in order to measure the inside diameter of the rocker arms. The standard rocker arm inside diameter is 15.985 to 16.005 mm (0.629 to 0.630 in).

27. Subtract the outside diameter measurement of the rocker arm shaft from the inside diameter measurement of the rocker arms to determine the rocker arm-to-rocker arm shaft clearance.
^ The standard rocker arm-to-rocker arm shaft clearance is 0.0011 to 0.036 mm (0.0001 to 0.0014 in).
^ The maximum rocker arm-to-rocker arm shaft is 0.09 mm (0.0035 in).

28. Replace the rocker arms and/or rocker arm shaft if the following exceed specification:
^ The rocker arm inside diameter
^ The rocker arm shaft outside diameter
^ The rocker arm-to-rocker arm shaft clearance





29. Use the J 8001 with the J 26900-13 in order to measure the camshaft (1) journal runout.
1. Place the camshaft (1) between two V-blocks and rotate slowly while measuring the journal runout. The maximum camshaft journal runout is 0.10 mm (0.0039 in).
2. Replace the camshaft if the camshaft journal exceeds 0.10 mm (0.0039 in).





30. Use the J 26900-1 in order to measure the camshaft (1) lobe height.
1. Measure the intake camshaft lobe height. The standard intake camshaft lobe height is 36.171 to 36.331 mm (1.4241 to 1.4303 in). The minimum intake camshaft lobe height is 36.071 mm (1.4202 in).
2. Measure the exhaust camshaft lobe height. The standard exhaust camshaft lobe height is 36.356 to 36.516 mm (1.4314 to 1.4376 in). The minimum exhaust camshaft lobe height is 36.256 mm (1.4275 in).
3. Replace the camshaft if any of the intake or exhaust camshaft lobes are below the minimum lobe height.

IMPORTANT: Do not rotate the camshaft with the plastic-type gaging material installed.

31. Use a plastic-type gaging material in order to measure the camshaft journal clearance.
1. Place one piece of the plastic-type gaging material the full width of a journal on each camshaft journal parallel to the camshaft.
2. Install the camshaft into the camshaft carrier in the cylinder head.

NOTICE: Refer to Fastener Notice in Service Precautions.





3. Install the camshaft carrier caps (1). Tighten the carrier cap bolts gradually in the specified order.
^ Tighten the camshaft carrier cap bolts to 10 Nm (89 inch lbs.).

4. Remove the camshaft carrier caps (1) carefully without disturbing the plastic-type gaging material.
5. Measure each piece of plastic-type gaging material at its widest point using the gaging scale provided on the plastic-type gaging material packaging.
^ The standard camshaft journal clearance is 0.040 to 0.082 mm (0.0016 to 0.0032 in).
^ The maximum camshaft journal clearance is 0.12 mm (0.0047 in).

6. Install the camshaft carrier caps onto the camshaft carrier. Tighten the camshaft carrier bolts to specification if the camshaft journal clearance exceeds 0.12 mm (0.0047 in).
7. Use a telescopic micrometer in order to measure the camshaft journal bore of the inside diameter.
8. Use the J26900-1 in order to measure the camshaft journal outside diameter.
^ The standard camshaft journal bore inside diameter is 28.000 to 28.021 mm (1.1024 to 1.1031 in).
^ The standard camshaft journal outside diameter is 27.939 to 27.960 mm (1.1000 to 1.1008 in).

9. Replace the camshaft if the camshaft journal outside diameter is farther out of specification than the camshaft journal bore inside diameter.
10. Replace the cylinder head if the camshaft journal bore inside diameter is farther out of specification than the camshaft journal outside diameter.

INSTALLATION PROCEDURE

^ TOOLS REQUIRED
- J 41040 Camshaft Sprocket Spanner Wrench

1. Apply clean engine oil to all rocker arm components to ensure the ease of assembly.





IMPORTANT: Rotate the rocker arm shaft (2) so that the flat machined surface is horizontal and facing down parallel with the cylinder head (1) mating surface.

2. Install the rocker arm shaft (2) by pushing the rocker arm shaft through the front of the cylinder head (1).
3. Slide the exhaust rocker arms and rocker arm springs as the rocker arm shaft is being installed.
4. Push the rocker arm shaft back through the rear of the cylinder head until the end of the rocker arm shaft appears.





5. Install a new O-ring (2) onto the rear of the rocker arm shaft (1).

NOTICE: Refer to Fastener Notice in Service Precautions.





6. Install the six rocker arm shaft bolts (1) into the cylinder head.
^ Tighten the rocker arm shaft bolts to 10 Nm (89 inch lbs.).

7. Fill the rocker arm shaft bolt holes with clean engine oil.
8. Install all of the intake rocker arm with the clips onto the rocker arm shaft (2).
9. Apply a liberal amount of clean engine oil to the camshaft.
10. Apply GM P/N 12346240 or the equivalent to the bottom of the number six camshaft carrier cap.

NOTICE: Always tighten the camshaft carrier cap bolts gradually and in the specified order. If the camshaft carrier cap bolts are tightened at random, damage to the camshaft may occur.

IMPORTANT: The camshaft carrier caps are embossed with numbers and arrows to ensure correct assembly. The number 1 camshaft carrier cap must be installed at the front of the cylinder head with the remaining carrier caps following in numerical order. The directional arrows must always point toward the front of the cylinder head.

11. Install the camshaft and the camshaft carrier caps onto the cylinder head. Secure the camshaft and the camshaft carrier caps with twelve bolts.
^ Tighten the camshaft carrier cap bolts to 10 Nm (89 inch lbs.).

12. Apply engine oil to the new camshaft seal lip.
13. Install the new camshaft seal into the cylinder head until the camshaft seal is flush with the camshaft carrier surface.





14. Install the new timing belt cover (2) to the cylinder head. Secure the timing belt inside cover (2) with two bolts.
^ Tighten the timing belt inside bolts to 10 Nm (89 inch lbs.).

15. Install the rocker arm shaft plug (1) into the cylinder head.
^ Tighten the rocker arm shaft plug to 33 Nm (24 ft. lbs.).

IMPORTANT: During the camshaft timing belt gear installation align the camshaft dowell pin (2) with the slot in the camshaft timing belt gear designated as E (3).





16. Using a J 41040 in order to hold the camshaft timing belt gear (1) stationary, install the camshaft timing belt gear onto the camshaft. Secure the camshaft timing belt gear with a bolt.
^ Tighten the camshaft timing belt gear bolt to 60 Nm (44 ft. lbs.).

17. Install the timing belt to the engine.





18. Apply GM P/N 12346240 or the equivalent to the surface of the distributor case that mates with the rear of the rocker arm shaft (2).
19. Install the distributor case (1) to the cylinder head. Secure the distributor case with three bolts.
^ Tighten the distributor case bolts to 10 Nm (89 inch lbs.).

20. Install the distributor into the distributor case.
21. Adjust the valve leash.
22. Install the cylinder head cover onto the cylinder head.
23. Install the radiator into the radiator core support.





24. Install the front end panel (1) to the vehicle. Secure the front end panel with the twelve bolts.
^ Tighten the front end panel bolts to 10 Nm (89 inch lbs.).

25. Install the two electrical connectors to the horn.
26. Install the hood latch to the front end panel. Secure the hood latch with two bolts.
^ Tighten the hood latch bolts to 10 Nm (89 inch lbs.).

27. Install the grille to the vehicle.
28. Connect the negative battery cable.