Service Manual

Weichai America Corp.
Revision: August 2019 79
14 APPENDIX B
Appendix B: Tolerance Clearance for Main Parts of Gas Engine (Reference value)
# Items Theoretical value (mm)
1
Main bearing clearance 0.05～0.11
2
Connecting rod bearing clearance 0.045～0.09
3
Crankshaft axial clearance 0.04～0.25
4
Connecting rod planar axial clearance 0.30～0.50
5 Clearance between the connecting rod small end bushing and
piston pin
0.03～0.08
6
Clearance between piston pin hole and piston pin 0.003～0.015
7
Clearance between valve stem and valve guide pipe 0.03～0.06
8
Piston ring’s gap in cold
state
The first (top) ring 0.35～0.55
The second ring 0.75～1.05
Oil ring
0.3～0.6
9
Piston ring end face gap in
cold state
The first (top) ring
The second ring
0.06～0.095
Oil ring
0.05～0.085
10
Plane values of valve bottom recess cylinder head 1.0～1.45
11
Plane values of cylinder liner top above the engine body 0.05～0.10
12
Camshaft axial clearance 0.10～0.29
13
Camshaft bearing clearance 0.04～0.08
14
Clearance between valve tappet and tappet hole 0.006～0.035
15 Plane clearance between the piston top and the cylinder head
bottom
0.88～1.11
16
Plane values of piston top above the engine block
0.25～0.57
17
Valve clearance (cold
state)
Intake 0.2
Exhaust 0.3
18 Clearance between rocker arm and rocker arm shaft
0.016～0.052
19 Gear backlash between timing gear and the intermediate gear 0.07～0.24
20
Clearance between positive and negative electrodes of the spark
plug
0.35±0.05
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