valve seals

[Saphire]

Is the possible to change valve seals without removing Cylinder Head?

[A.P.V.]

in a M10, no.
in a M20, yes

[Corrado]

Not entirely true. Begin with the piston at bottom dead center, just before the compression stroke. Remove the spark plug and feed a length of rope down into the cylinder. Once you have loosely filled the cylinder with rope, begin to turn the crankshaft in the normal direction until resistance is felt. Now with your spring compressor, you can push down on your springs without worry that your valves will drop inside the engine.