1999 Volvo Penta "WT" Models Workshop Manual, Page 243Get this manual
6Valve keys as follows: aCompress the valve spring using 8062 Valve Spring CompressorCompress the spring enough to clearly see the valve stem groovebApply small amount of grease to the valve keys to hold them in placeMake sure the keys are properly seated in the valve stem groovescRemove the compressor toolMake sure the valve keys stay in placedRepeat the procedure on the remaining valves m m
7Measure the installed height of each valve spring uSing the following procedure: aUse narrow, thin scaleA cut away scale may be helpfulbMeasure from the cylinder head spring seat to the top of the capIf this measurement exceeds the amount given under Specifications found in this manual, install the valve spring shims of sufficient thickness between the rotator and the cylinder head in order to give the desired measurementNever shim the spring so as to give an installed height under the specified amount