1971 Johnson 40HP outboards Service Manual, Page 8Get this manual
CLEARANCE CHART POWER HEAD Piston ring gap .017 Max- .007 MinPropeller shaft in front gear bushing .0020 Max- .0010 Min
Piston ring groove .0040 Max- .0015 Minclearance, lower Rear reverse gear .0020 Max- .0005 Minto rear bushing 0006 Max- .0001 Min Piston pin to pistonloose end Cylinder and piston
.0045 Max- .0030 Min.011 Max- .003 Min
Reverse gear bushing to propeller shaft Propeller on shaft at drive pin hole
.0015 Max- .0005 Min
Crankshaft end play LOWER UNIT Driveshaft upper
.007 Max- .003 Min
Roller Propeller on shaftabove the shoulder 0069 Max- .0034 Min
TORQUE CHART
POWER HEAD Flywheel nut Connecting rod screw Cylinder head screws 100105 Foot-pounds 348372 Inch-pounds (2931 Foot-pounds) 168192 Inch-pounds LOWER UNIT Side mounts upper and lower nuts Front mount upper nut Pilot shaft to steering bracket screws Pull at propeller shaft for tilt up lower units Pull at propeller shaft to overcome reverse lock STANDARD SCREWS When tightening two or more screws on the same part, DO NOT tighten screws completely, one at timeTo avoid distortion of the part, first tighten all screws together to one-third of specified torque, then to two-thirds of specified torque, then torque down completelyNOTE: Re-check torque on cylinder head screws and spark plugs after motor has been runhas reached operating temperatureand motor has cooled comfortable to touchStandard length lower unit40 1