How do you clean car engine valves?

I have tried wire brush on a drill press -high speed. This will remove crud. Make sure not to hit stem that enters valve guide.

BUT I would only recommend: Take them to a rebuilding shop for sandblasting. Any decent shop will throw in quick valve inspection and free advice.

Be sure to tag each valve with colored twist ties, tags, etc. Ink might be removed. The shop will have its own I.D. method.