WEICHAI & PSI SERVICE MANUALS AVAILABLE ONLINE AT FLYPARTSGUY.COM Weichai America Corp. 14 APPENDIX B Appendix B: Tolerance Clearance for Main Parts of Gas Engine (Reference value) Revision:
August 2019 79 GET YOUR WEICHAI & AFTERMARKET SERVICE PARTS AT FLYPARTSGUY.COM # 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