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XI Cylinder Head
Preparatory data 11.1
Fault diagnosis 11.2
Cylinder Head/Valve 11.3
11.1 Preparatory Data
Function of cylinder head:
Cylinder head is used to seal cylinder and form a combustion chamber with piston to hold high-temperature
and high-pressure fuel gas. It accomplishes air intake and exhausting operation with valve mechanism.
Precautions on Operation
To ensure sealing between cylinder head and cylinder body, there is a great bolt pretension on the cylinder
head. Pre-tightening force value 12 N·m; Locking force value: 30 N·m.
All the components shall be cleaned before inspection and test, and purged with high-pressure air.
Table of standard values of baseline projects and allowable limit Unit: mm
Item Standard Service Limit
Cylinder cover flatness 0.03 0.05
Val ve
Valve guide
Valve clearance
Intake 0.15-0.2 -
Exhaust 0.2-0.25 -
Valve stem OD
Intake 4.47-4.48 4.455
Exhaust 4.455-4.47 4.448
Valve guide ID
Intake 4.5-4.512 4.53
Exhaust 4.5-4.512 4.53
Clearance between valve
stem and valve guide
Intake 0.02-0.042 0.075
Exhaust 0.03-0.057 0.082
Val v e r a ce wid t h
Intake 0.9-1 1.6
Exhaust 1-1.1 1.6
Valve spring Free length
Intake 39.5 37
Exhaust 39.5 37
Cam shaft
Fit clearance between the cam shaft and
the cylinder head
0.02-0.054 0.08
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