Tools Required

• J 36660-A Torque Angle Meter
• J 42038 Camshaft Holding Fixture
• J 43032 Crankshaft Rotation Socket

Setting the camshaft timing is necessary whenever the camshaft drive system has been disturbed such that the relationship between any chain and sprocket has been lost. Even when only one sprocket is involved the following procedure should be observed since one crankshaft rotation will not provide conditions where correct timing can be confirmed.

The camshafts, crankshaft and balance shaft events are correctly timed when the relationships shown exist. The following procedure explains how to establish this condition.

1. Remove the following components for access:
   • The left camshaft cover, Refer to Camshaft Cover Replacement - Left .
   • The right camshaft cover. Refer to Camshaft Cover Replacement - Right .
   • The primary camshaft drive chain tensioner. Refer to Primary Camshaft Drive Chain Tensioner Replacement .
   • The primary camshaft drive chain tensioner shoe. Refer to Primary Camshaft Drive Chain Tensioner Shoe Replacement .
   • The camshaft position sensor. Refer to CRANKSHAFT POSITION SENSOR in Engine Controls -3.5L
2. Ensure the following components are positioned accordingly:
   • The crankshaft is at TDC of the # 1 cylinder compression stroke.
   • The 4 camshaft drive pin notches upward.
3. Use an open end wrench on the hex cast into the camshaft to aid in the installation of the J 42038.
   WARNING: The camshaft holding tools must be installed on the camshafts to prevent camshaft rotation. When performing service to the valve train and /or timing components, valve spring pressure can cause the camshafts to rotate unexpectedly and can cause personal injury
Fig 1: Using Open End Wrench On Hex Cast Into Camshaft
Courtesy of GENERAL MOTORS CORP.
4. Install the J 42038 to the rear of the camshafts on the left and right cylinder heads.
   Fig 2: Identifying J 42038

   Courtesy of GENERAL MOTORS CORP.
5. Compress the left secondary drive chain tensioner shoes with your hand.
6. Lock the left secondary drive chain tensioner by inserting a piece of wire (2) into the access hole in the side of the tensioner (1).
7. Slowly release the pressure from the left secondary drive chain tensioner shoes. The tensioner should remain closed.
   Fig 3: Locking Left Secondary Drive Chain Tensioner

   Courtesy of GENERAL MOTORS CORP.
8. Wrap the left secondary timing chain around both secondary drive sprockets.
9. Align the exhaust sprocket drive pin (1) between the 2 darkened links (2).
10. Align the intake sprocket drive pin (4) with the single darkened link (3).
    Fig 4: Identifying Right Secondary Camshaft Timing Components Position

    Courtesy of GENERAL MOTORS CORP.
11. Fit the intake and exhaust camshaft sprockets with the secondary timing chain onto their respective camshafts and align the drive pins in the camshafts.
    CAUTION: Refer to FASTENER NOTICE in Cautions and Notices.
12. Install the camshaft sprocket bolts.

    Tighten 

    1. 12.1. Tighten the camshaft sprocket bolts to 25 N.m (18 lb ft).
    2. 12.2. Tighten the camshaft sprocket bolts an additional 45 degrees using the J 36660-A.
13. Remove the locking wire from the left secondary drive chain tensioner allowing the tensioner shoes to expand and apply pressure to the drive chain.
    Fig 5: Installing Camshaft Sprocket Bolts

    Courtesy of GENERAL MOTORS CORP.
14. Compress the right secondary drive chain tensioner shoes with your hand.
15. Lock the right secondary drive chain tensioner by inserting a piece of wire (2) into the access hole in the side of the tensioner (1).
16. Slowly release the pressure from the right secondary drive chain tensioner shoes. The tensioner should remain closed.
    Fig 6: Locking Right Secondary Drive Chain Tensioner

    Courtesy of GENERAL MOTORS CORP.
17. Wrap the right secondary timing chain around both secondary drive sprockets.
18. Align the intake sprocket drive pin (1) between the 2 darkened links (2).
19. Align the exhaust sprocket drive pin (4) with the single darkened link (3)
    Fig 7: Identifying Right Secondary Camshaft Timing Components Position

    Courtesy of GENERAL MOTORS CORP.
20. Fit the intake and exhaust camshaft sprockets with the secondary timing chain onto their respective camshafts and align the drive pins in the camshafts.
21. Install the camshaft sprocket bolts.

    Tighten 

    1. 21.1. Tighten the camshaft sprocket bolts to 25 N.m (18 lb ft).
    2. 21.2. Tighten the camshaft sprocket bolts an additional 45 degrees using the J 36660-A.
22. Remove the locking wire from the right secondary drive chain tensioner allowing the tensioner shoes to expand and apply pressure to the drive chain.
    Fig 8: Installing Intake & Exhaust Camshaft Sprockets & Bolts

    Courtesy of GENERAL MOTORS CORP.

    Important:  Do not allow the primary camshaft drive chain to fall into the crankcase.

23. Install the primary camshaft drive chain into the front cover area.
    Fig 9: Installing Primary Camshaft Drive Chain

    Courtesy of GENERAL MOTORS CORP.

    Important:  Do not remove the J 42038.

24. To assist in primary camshaft drive chain installation, use an open end wrench on the hex cast into the camshaft to provide minor adjustments to the secondary sprocket position.
    Fig 10: Using Open End Wrench On Hex Cast Into Camshaft

    Courtesy of GENERAL MOTORS CORP.
25. When installing the primary camshaft drive chain you must set the base engine timing. Base engine timing is set with cylinder number one at top dead center (TDC) starting the intake stroke and with the correct camshaft to balance shaft to crankshaft relationship. To set the correct base engine timing proceed as follows:
    1. 25.1. Rotate the crankshaft until cylinder number one is at top dead center and the crankshaft sprocket timing mark (6) is at the 4 o'clock position using the J 43032.
    2. 25.2. Rotate the balance shaft until its timing mark (7) is at the 5 o'clock position.
26. Make sure the darkened chain links on the primary camshaft drive chain are facing outward.
    Fig 11: Identifying Drive Chain Markings

    Courtesy of GENERAL MOTORS CORP.
27. Center the timing mark (1) on the left hand intake camshaft between the paired darkened timing links (2) and wrap the chain around the sprocket. Allow the remainder of the primary camshaft drive chain to drop into the crankcase area once the timing mark is aligned.
28. Fabricate a hook out of wire and feed it down through the right cylinder head. Use the hook to pull the remainder of the primary camshaft drive chain up to the right intake camshaft sprocket.
29. While pulling the timing chain up to the right cylinder head, align the darkened chain links with the balance shaft (7) and crankshaft (6) sprockets.
30. Wrap the primary camshaft drive chain around the right intake camshaft sprocket and align the darkened link (8) with the sprocket's timing mark (9).
31. Install the primary camshaft drive chain tensioner shoe. Refer to Primary Camshaft Drive Chain Tensioner Shoe Replacement .
32. Install the primary camshaft drive chain tensioner. Refer to Primary Camshaft Drive Chain Tensioner Replacement .
33. Remove the J 42038 from the rear of the camshafts on the left and right cylinder heads.
    Fig 12: Identifying J 42038

    Courtesy of GENERAL MOTORS CORP.
34. Make sure all the timing marks (1,6,7,9) are properly aligned with the darkened chain links (2,3,5,8).
35. Install the following components:
    • The left camshaft cover. Refer to Camshaft Cover Replacement - Left .
    • The right camshaft cover. Refer to Camshaft Cover Replacement - Right .
    • The camshaft position sensor. Refer to CRANKSHAFT POSITION SENSOR in Engine Controls- 3.5L.
    Fig 13: Identifying Drive Chain Markings

    Courtesy of GENERAL MOTORS CORP.