What does Milled mean? What does decked mean? What does extruded mean?

 

A mill is a type of material removal machine. When you "mill" your heads, you remove material from the sealing surface to the block.

"Decking" is milling the block on the "deck" surface that seals to the head.

These operations are done to true up the flatness of the sealing surface, and to a lesser degree (but which is more commonly discussed) as a performance improvement for compression ratio or quench area changes (need "quench" defined?).

To extrude is to force through under pressure. You're probably referring to a process called "extrude honing" which forces an abrasive paste through passages to smooth them out.

 

Thanks alot five7kid! That helped alot. And yes what is "quench"?

 

quench is the area between the piston and chamber. it's a variable depending on piston design, gasket thickness, and chamber size, and a few other factors