2006 Johnson SD 30 HP 4 Stroke Outboards Service Manual, PN 5006592, Page 143Get this manual
POWERHEAD CYLINDER HEAD If the measurement exceeds the service limit, replace the rocker arm andor the shaft
Valve Stem and Valve Guide
Use micrometer to measure the outside diameter of the valve stems Be sure to take readings at more than one place along the length of each valve stem
Rocker Arm-to-Shaft Clearance 0.00050.0018 inStandard (0.0120.045 mm) Service Limit 0.0035 in(0.090 mm)
Valve Stem Outside Diameter 0.21520.2157 inIntake valve (5.4655.480 mm) 0.21460.2152 inExhaust valve (5.4505.465 mm)