Adjusting Valve Clearance

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Disconnect Harness

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Remove Rocker Arm Cover

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Flywheel Turning Tool and Timing Pin

A - Wiring Harness

B - Rocker Arm Cover

C - JDG820 Flywheel Turning Tool

D - JDE81-4 Timing Pin

CAUTION: To prevent accidental starting of engine while performing valve adjustments, always disconnect NEGATIVE (—) battery terminal.

IMPORTANT: Valve clearance MUST BE adjusted with engine COLD. Accurate valve adjustment is critical for maximum engine performance.

1. Disconnect wiring harness (A).

2. Remove rocker arm cover (B) with vent tube.

   IMPORTANT: Visually inspect contact surfaces of valve tips and rocker arm wear pads. Check all parts for excessive wear, breakage, or cracks. Replace parts that show visible damage.

   Rocker arms that exhibit excessive valve clearance should be inspected more thoroughly to identify damaged parts.

3. Remove plastic plugs from cylinder block bores and install JDG820 Flywheel Turning Tool (C) and JDE81-4 Timing Pin (D).

4. 
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   Valve Clearance Setting Procedure

   
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   Checking Valve Clearance Using Bent Feeler Gauge

   
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   Valve Adjusting Sequence - No. 1 Cylinder at TDC

   A - Rocker Arm Foot

   B - Feeler Gauge Access

   C - Front of Engine

   Rotate engine with the flywheel turning tool until timing pin engages timing hole in flywheel.

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5. If the rocker arms for No. 1 (front) cylinder are loose, the engine is at No. 1 TDC-Compression.

6. If the rocker arms for No. 6 (rear) cylinder are loose, the engine is at No. 6 TDC-Compression. Rotate the engine one full revolution (360 degrees) to No. 1 TDC-Compression.

7. NOTE: To assist in adjusting valve clearance, push the rocker arm foot forward (A) for easier feeler gauge access (B)

   With engine lock-pinned at “TDC” of No. 1 piston's compression stroke, use a bent feeler gauge to check valve clearance on Nos. 1, 3, and 5 exhaust valves and Nos. 1, 2, and 4 intake valves. If out of specification, loosen lock nut on rocker arm adjusting screw. Turn adjusting screw until feeler gauge slips with a slight drag. Hold the adjusting screw from turning with screwdriver and tighten lock nut to specifications.

   Item	Measurement	Specification
   Intake Valve Clearance (Rocker Arm-to-Valve Tip With Engine Cold)	Clearance	0.18 mm (0.007 in.)
   Exhaust Valve Clearance (Rocker Arm-to-Valve Tip With Engine Cold)	Clearance	0.64 mm (0.025 in.)
   Valve Adjusting Screw Lock Nut	Torque	27 N•m (20 lb-ft)

   Recheck clearance again after tightening lock nut. Readjust clearance as necessary.

8. 
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   Valve Adjusting Sequence - No. 6 Cylinder at TDC

   A - Front of Engine

   Remove timing pin and rotate flywheel 360° and install timing pin. No. 6 piston is now at “TDC” of its compression stroke. Rocker arms for No. 6 piston should be loose.

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9. Check and adjust valve clearance to the same specifications on Nos. 2, 4, and 6 exhaust and Nos. 3, 5, and 6 intake valves.

10. IMPORTANT: Replace rocker arm cover gasket whenever rocker arm cover is removed.

    Install new rocker arm cover gasket.

11. 
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    Rocker Arm Cover Torque Sequence

    A - Front of Engine

    Install rocker arm cover with vent tube and tighten cap screws finger tight in sequence shown. Then tighten screws in same sequence to specification.

    Item	Measurement	Specification
    Rocker Arm Cover Cap Screws	Torque	35 N•m (26 lb-ft)

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12. Connect wiring harness.

13. Remove timing pin and flywheel turning tool. Install plastic plugs in block.