2006 Johnson SD 30 HP 4 Stroke Outboards Service Manual, PN 5006592, Page 144Get this manual
POWERHEAD CYLINDER HEAD Subtract the valve stem outside diameter from the valve guide inside diameter to determine the valve guide-to-stem clearanceIf the measurement exceeds the service limit, replace the valve guide andor the valveValve Guide-to-Stem Clearance 0.00080.0019 inIN (0.0200.047 mm) Standard 0.00140.0024 inEX (0.0350.062 mm) IN 0.0028 in (0.070 mm) Service Limit 0.0035 in(0 .090 mm) EX If the valve guide inside diameter cannot be measured, use dial gauge to check the valve stem end deflection to determine whether the valve guide-to-stem clearance is adequate Install the valve into the valve guide Position the valve head approximately 0.2 in(5.0 mm) away from the valve seat Move the stem end back and forth and measure the deflectionIf the measurement exceeds the service limit, replace the valveIf the measurement still exceeds the service limit with new valve installed, replace the valve guideValve Stem End Deflection IN 0.006 in(0.14 mm) ervlce Iml EX 0.007 in(0.18 mm) Inspect the valve stem end face for pitting and wearThe valve stem end may be refaced Be careful not to wear down the chamfer too farUse vernier calipers to measure the valve stem end length If the measurement is less than the specification, the chamfer is too worn Replace the valveValve Stem End Length IN 0.276 in (7.00 mm) ervlce Iml EX 0.236 in (6.00 mm)