Tools Required

1. Remove the thermostat housing. Refer to Engine Coolant Thermostat Replacement in Engine Cooling.
2. Remove the left camshaft cover. Refer to Camshaft Cover Replacement - Left Side .




Important: You must install the J 42038 immediately after cam cover removal. The J 42038 prevents unexpected camshaft rotation caused by valve spring pressure.

3. Install the J 42038 on to the left camshafts.

When installed properly the J 42038 will be fully seated on the camshaft ends with the camshaft flats parallel to the cam cover sealing surface.

4. Compress the secondary timing chain tensioner with your hand.
5. Lock the tensioner by inserting a piece of wire (2) into the access hole in the side of the tensioner.
6. Slowly release pressure on the tensioner. The tensioner should remain compressed.
7. Remove the camshaft sprocket bolts.



8. Install the J 42042 on to the left cylinder head.
9. Evenly slide the secondary drive chain and camshaft sprockets off the camshafts on to the J 42042 .



10. Observe the markings on the bearing caps. Each bearing cap is marked in order to identify its location. The markings have the following meanings:

•	The raised feature must always be oriented toward the outboard of the engine.

•	The "I" indicates the intake camshaft.

•	The "E" indicates the exhaust camshaft.

•	The number indicates the journal position from the front of the engine.




11. Remove the camshaft bearing cap retaining bolts.
12. Remove the camshaft bearing caps. The cap closest to the front of the engine is the thrust cap and must not be installed in another location.
13. Remove the J 42038 from the left camshafts. Allow the camshaft lobes to find a neutral position by rotating each camshaft, if necessary. DO NOT rotate the camshafts more than 10 degrees.



14. Lift the camshaft (1 or 2) out of the cylinder head.
15. Clean and inspect the camshaft. Refer to Camshaft Cleaning and Inspection .
16. Cover the camshaft with an oil soaked towel in order to prevent corrosion.

1. Apply a liberal amount of camshaft and lifter prelube GM P/N 12345501 or equivalent to the roller (2), lash adjuster and valve tip areas (1) of the camshaft followers.




Important: The follower must be positioned squarely on the valve tip so that the full width of the roller will completely contact the camshaft lobe. If the followers are being reused you must put them back in their original location.

2. Place the camshaft followers in position on the valve tip and lifter. The rounded head end of the follower goes on the lash adjuster while the flat end goes on the valve tip.
3. Clean the camshaft journals and carriers with a clean, lint-free cloth.




Important: Use the J 43032 in order to make sure that the crankshaft is in the TDC position.

4. Select the proper camshaft for the particular installation location. The left cylinder head camshafts (1, 2) are longer than those for the right cylinder head (3, 4). However, both sets of camshafts share the same placement of identification rings. The ring placement is defined as follows:

4.1.	The identification ring for the intake camshafts (1, 3) is located between the first and second sets of lobes.

4.2.	The identification ring for the exhaust camshafts (2, 4) is located between the second and third sets of lobes.




5. Apply a liberal amount of camshaft and lifter prelube GM P/N 12345501 or equivalent to the camshaft journals and the cylinder head camshaft carriers.
6. Place the intake (1) and exhaust (2) camshafts in position in the cylinder head.
7. Position the camshaft lobes in a neutral position with the front notch for the camshaft sprocket drive pins near the top of their rotation and the rear flats of the camshaft near the installation position of the J 42038 .



8. Observe the markings on the bearing caps. Each bearing cap is marked in order to identify its location. The markings have the following meanings:

•	The raised feature must always be oriented toward the outboard of the engine.

•	The "I" indicates the intake camshaft.

•	The "E" indicates the exhaust camshaft.

•	The number indicates the journal position from the front of the engine.




9. Install the camshaft bearing thrust caps in the first journal of each camshaft. The thrust caps are wider than the others and have machined undercuts not present on the other caps. Make sure the orientation marking is closest to the engine valley.
10. Install the remaining bearing caps with their orientation mark closest to the engine valley.
11. Hand start all the camshaft bearing cap bolts.

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.

12. Tighten the camshaft bearing caps.

Tighten

1. Tighten the camshaft bearing cap bolts to 8 N·m (71 lb in).
2. Use theJ 36660-A in order to tighten the camshaft bearing cap bolts an additional 22 degrees .




Important: Do not rotate the camshaft more than 10 degrees.

13. Using the hex cast into the camshaft, rotate the camshaft so the rear camshaft flat is facing the cylinder head.
14. Install the J 42038 at the rear of the cylinder head.




Important: The camshafts must be locked in place using the J 42038 before installation of the secondary timing chain.

15. Make sure the locking tool is fully seated and locked onto the camshafts.



16. Slide the intake and exhaust camshaft sprockets off of the J 42042 and onto their respective camshafts and align the drive pins (1) in the camshafts.



17. Remove the J 42042 from the left cylinder head.
18. Install the intake camshaft sprocket bolt and exhaust camshaft sprocket bolt.

Tighten

1. Tighten the camshaft sprocket bolts to 25 N·m (18 lb ft).
2. Use theJ 36660-A in order to tighten the camshaft bearing cap bolts an additional 45 degrees .
19. Remove the locking wire from the secondary timing chain tensioner allowing the tensioner shoes to expand and apply pressure to the timing chain.



20. Remove the J 42038 from the left camshafts.
21. Install the left camshaft cover. Refer to Camshaft Cover Replacement - Left Side .
22. Install the thermostat housing. Refer to Engine Coolant Thermostat Replacement in Engine Cooling.