Thanks for the suggestions, but...
I do not have that kind of scanner (called a blue-light scanner or white-light scanner). Hardly anyone does. Well, except the Chinese do have plenty of them... that's how they copy our stuff! I cannot make a CAD model without a 3D scanned model, or the data from a blueprint. I can manually measure an existing valve cover, it just isn't the easiest thing in the world to do. Fortunately I work in a machine shop that employs some very good layout inspectors that are willing to help.
