It can be done, but it is classified under the engine overhaul reconditioning, which can be time consuming and expensive for an engine machinist to do. To do it yourself is not usually recommended.---
REMOVAL & INSTALLATION
A valve spring compressor is needed to remove the valves and springs; these are available at most auto parts and auto tool shops. A small magnet is very helpful for removing the keepers and spring seats.
Set the head on its side on the bench. Install the spring compressor so that the fixed side of the tool is flat against the valve head in the combustion chamber, and the screw side is against the retainer. Slowly turn the screw in towards the head, compressing the spring. As the spring compresses, the keepers will be revealed; pick them off of the valve stem with the magnet as they are easily fumbled and lost. When the keepers are removed, back the screw out and remove the retainers and springs. Remove the compressor and pull the valves out of the head from the other side. Remove the valve seals by hand and remove the spring seats with the magnet.
Fig. 1: After compressing the valve spring, be careful removing the keepers--they are easily fumbled
Fig. 2: Always install new valve stem seals
Fig. 3: Lightly tap each assembled valve stem to ensure correct fit of the keepers, retainer and seals
Fig. 4: Special tool to remove the valve spring--you also need tool to hold valve up
Fig. 5: Removing the keepers with a magnet
Fig. 6: Removing the valve spring
Fig. 7: Removing the valve seal
Fig. 8: Installing the valve seal
Since it is very important that each valve and its spring, retainer, spring seat and keepers is reassembled in its original location, you must keep these parts in order. The best way to do this to cut either eight (four cylinder) or twelve (six cylinder) holes in a piece of heavy cardboard or wood. Label each hole with the cylinder number and either IN
EXp>After lapping each valve into its seat (see Valve Lapping below), oil each valve stem, and install each valve into the head in the reverse order of removal, so that all parts except the keepers are assembled on the stem. Always use new valve stem seals. Install the spring compressor, and compress the retainer and spring until the keeper groove on the valve stem is fully revealed. Coat the groove with a wipe of grease (to hold the keepers until the retainer is released) and install both keepers, wide end up. Slowly back the screw of the compressor out until the spring retainer covers the keepers. Remove the tool. Lightly tap the end of each valve stem with a rubber hammer to ensure proper fit of the retainers and keepers.