Introduction
Use this procedure for adjusting valves on C8.7L engines.
Specifications
| Parameter | Value |
|---|---|
| Inlet Valves | 0.40 ± 0.05 mm (0.016 ± 0.002 inch) |
| Exhaust Valves | 0.60 ± 0.05 mm (0.024 ± 0.002 inch) |
| Rocker arm adjustment nut | 39 ± 5 N·m (29 ± 4 lb ft) |
| Firing Order |
|---|
| 1-4-2-6-3-5 (1) |
| ( 1 ) | The No. 1 cylinder is at the front of the engine. |
| Adjust Cylinder | Valves Open at Cylinder | |
| 1 TDC | 1 | 6 |
| Rotate 120 degrees | 4 | 3 |
| Rotate 120 degrees | 2 | 5 |
| Rotate 120 degrees | 6 | 1 |
| Rotate 120 degrees | 3 | 4 |
| Rotate 120 degrees | 5 | 2 |
Note: The valve lash must be checked and adjusted by the proper sequence shown above. Rotate the engine in direction of rotation.
Required Tools
| Qty | Part Number |
|---|---|
| 1 | 456-7994 Engine Turning Tool |
| 1 | 456-7990 Timing Pin |
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| Illustration 1 | g03703198 |
Typical example of the 456-7994 Engine Turning Tool | |
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| Illustration 2 | g03703217 |
Typical example of the 456-7990 Timing Pin | |
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| Illustration 3 | g03811735 |
(A) Hole on flywheel with a notch corresponding to pistons 3-4 TDC (B) Hole on flywheel with 2 notches, position corresponding to 54° before Cylinder 1 and 6 at TDC (C) Hole on flywheel with a notch corresponding to pistons 2-5 TDC (D) Hole on flywheel with a notch, corresponding to piston 1-6 TDC | |
Valve Lash Check
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To prevent possible injury, do not use the starter to turn the flywheel. Hot engine components can cause burns. Allow additional time for the engine to cool before measuring valve clearance. |
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| Illustration 4 | g03703086 |
Cylinder and valve location (A) Exhaust valves (B) Inlet valves | |
An adjustment is not necessary if the measurement of the valve lash is in the acceptable range in Table 1.
If the measurement is not within the specified range, an adjustment is necessary. Refer to "Valve Lash Adjustment" for the proper procedure. Adjust the valve lash before proceeding to the next cylinder.
- Use turning tool (1) to put the No. 1 piston at the top center position on the compression stroke. Rotate the engine in direction of normal rotation. Refer to Testing and Adjusting, "Finding Top Center Position for No. 1 Piston".
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| Illustration 5 | g03703174 |
(1) 456-7994 Engine Turning Tool (C) Inspection hole (D) Double notch (E) Single notch | |
- Install timing pin (2) into the flywheel.
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| Illustration 6 | g03703225 |
(2) 456-7990 Timing Pin | |
- Check the inlet and exhaust valve lash for cylinder No. 1 using a feeler gauge.
- Remove timing pin (2) .
- Rotate the engine in direction of rotation 120 degrees using turning tool (1) . A single notch should be visible.
- Install timing pin (2) into the flywheel.
- Check the inlet and exhaust valve lash for cylinder No. 4 using a feeler gauge.
- Remove timing pin (2) .
- Refer to Table 3 for the proper sequence to check the remaining cylinders.
Valve Lash Adjustment
Use the following procedure to adjust the valve lash:
- Ensure that the No. 1 piston is at the top center position on the compression stroke. Refer to Step 1.
- Adjust the valve lash according to Table 1.
- Lightly tap the rocker arm with a soft mallet. This tapping will ensure that the lifter roller seats against the camshafts base circle.
- Loosen the adjustment locknut.
- Place the appropriate feeler gauge between rocker arm and the valve bridge. Then, turn the adjustment screw in a clockwise direction. Slide the feeler gauge between the rocker arm and the valve bridge. Continue turning the adjustment screw until a slight drag is felt on the feeler gauge. Remove the feeler gauge.
- Tighten the adjustment locknut to a torque of 39 ± 5 N·m (29 ± 4 lb ft). Do not allow the adjustment screw to turn while you are tightening the adjustment locknut. Recheck the valve lash after tightening the adjustment locknut.
- Refer to Table 3 for the proper sequence to adjust the remaining cylinders.