Because of the challenge involved and the kind of equipment needed to work on the valves, the valve seats, and the valve guides it is advisable to engage the services of a professional. Home mechanic can take off and unbolt the head, perform rudimentary thorough washing and examination of the head and then he/she can present it to a dealer service department, or to a professional automotive machine shop for the actual valve servicing. The service department or the machine shop will have to have to strip the valves and springs, recondition or replace according to the need, inspect and replace the valve springs as contained in the specification, also replace the retainers, rotators and keepers if need be, replace the valve seals, reassemble the part and finally correctly set the installed spring height. Further, Cylinder head gasket surface will be grind as well if it is warped. That is always the case after performing the valve job, and the head will be almost as good as new. It should be washed before being placed in the head on the engine so as to purge it of any metal chips and sand that may be left behind during the service or after resurfacing. Compressed air should be utilised, if available, to blow out all oil holes and passages.