[asphaltgambler]

The valve/seat grinding work is performed (oddly enough) with a valve grinding machine. Very expensive so only most auto machine shops have them, not something the average home mechanic would have. Also the best machine is nothing w/o an experienced operator. I've seen some real messes even though the shop had very nice equipment.

Guide install /modification is with basic hand tools coupled with a simple tool that finds instant center for the guide. Depending on the type they also may use a small press and or heat to smoothly assist in removal or install.

Port/polishing has been done in the past with high-rpm small hand-held grinders with either carbide cutting bits or stones depending on the material and the amount removed. Very similar to a dentists' drill. Very labor intensive and time consuming. One mistake could ruin the part.


The newer method for porting /polishing is extrude-hone. Basically a machine forces a toothpaste-like metal compound with force through the opening to make it more uniform, larger and with a certain finish. Much faster and precise but it has limitations.

Dual plugging is usually performed on a mill. Basically a large, very precise low-speed drill press. Again these are very expensive so not every shop will have one.