If you have the proper equipment, and the valve material is good, you can machine finished valves from a valve blank.
Problems can arise from insufficient radii in critical stress areas, and insufficient cross sections in load areas. Also, if you have a valve that requires a hardened wear surface as in a rocker actuated valve, the correct application of the optimum hard weld material is important. Finally, you cannot feed to rapidly into a valve when cutting down the head diameter as the stem may flex away from the tool causing concentricity problems. This is especially a problem as you work on the smaller stem diameters.
If you have a head size and stem diameter that you want to work to we may have a valve blank that you can machine yourself. Or, if you can supply a sample or drawing we could make a valve to your specs.
Most of the time a finished custom valve with a hardweld tip goes out for about $46.00.
You can call and ask to speak to one of our techs at 650-359-4704.
Best Regards-
Mike Perry
Kibblewhite Precision Machining Inc.