For 1990-2009 cars

1. Ensure that the camshaft sealing rings (1) are in place in the camshaft grooves. Camshaft sealing rings must be in place below the surface of the camshaft journal in order to avoid being pinched between the cylinder head and the camshaft caps.
2. Apply a liberal amount of lubricant GM P/N 12345501 (Canadian P/N 992704) or equivalent to the camshaft journals and the left cylinder head camshaft carriers.
3. Place the left intake and left exhaust camshafts in position in the left cylinder head.
4. Position the camshaft lobes in a neutral position with the flats on the back of the camshafts up and parallel (1) with the left cylinder head camshaft cover rail.
5. Observe the markings on the left cylinder head camshaft 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 center of the cylinder head.

• | The I indicates the intake camshaft.

• | The E indicates the exhaust camshaft.

• | The number 2, 4, 6 indicates the cylinder position from the front of the engine.

6. Apply a liberal amount of lubricant GM P/N 12345501 (Canadian P/N 992704) or equivalent to the camshaft bearing caps.
7. Install the camshaft bearing thrust cap in the first journal of the left cylinder head.
8. Install the remaining bearing caps with their orientation mark toward the center of the cylinder head.
9. Hand start all the camshaft bearing cap bolts.

Caution: Refer to Fastener Caution in the Preface section.

10. Tighten the camshaft bearing cap bolts in sequence to 10 N·m (89 lb in).
11. Loosen the center intake camshaft bearing cap bolts 1, 2 and the center exhaust camshaft bearing cap bolts 3, 4.
12. Retighten the center camshaft bearing cap bolts 1, 2, 3, 4 to 10 N·m (89 lb in).