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7 Checking and setting
7.1 Adjustment of valve clearance
7.1.1 General information
The valve clearances are to be adjusted at the times of the following situations.
• After initial 50 hour’s operation.
• When the engine is overhauled and the cylinder heads are disassembled.
• When abnormal noise comes from valve train.
• When the engine is not normally operated, even though there is no trouble in the fuel system.
The valve clearance of the cold engine are as follows.
- Intake valves : 0.35mm
- Exhaust valves : 0.35mm
7.1.2 Adjusting order of the valve clearance
1) Turn the flywheel so that Cyl.No.1 is at TDC, ensure that it is compression TDC, adjust the valve
clearances. Adjust valve clearances when engine is cold.
2) Loosen the lock nuts of rocker arm adjusting screws and push the feeler gauge of specified value
between a rocker arm and a valve bridge and adjust the clearance with adjusting screw respectively
and then tighten with the lock nut.
Model Intake Valve Exhaust Valve
DV8/DV10/DV12 0.35 mm 0.35 mm
Then turn the cranshaft as follows for adjusting valve clearances of other cylinders ( Follow firing order ) :
• DV8 Engine - Rotate by 90
0
each time to adjust valve clearance of successive cylinder.
• DV10 Engine - Rotate by 54
0
for & 90
0
alternatively
• DV12 Engine - Rotate by 60
0
each time to adjust valve clearance of successive cylinder.
3) No. 1 Cylinder is located at the side where flywheel was installed.
7.1.3 Method of adjusting the valve clearance
1) Loosen the lock-nuts using a ring spanner.
2) Insert a thickness gauge of 0.35 mm between valve bridge and rocker arm.
3) Turn the adjusting screw using a screw driver until the gauge can be pulled out with some restriction.
4) After the adjustment fix the adjusting screw not to rotate and tighten the lock-nut at the same time.
5) Measure the clearance one more time and if necessary adjust again.
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