The " How To" on putting a nice level, even finish to the cylinder head port, or intake port.
BASIC LEVELING
The next step is basic leveling and removal of waves, ripples, etc. There are many different tools to use for this, such as an abrasive stone, sanding drums, spiral rolls, slotted mandrel with emery cloth, abrasives, etc. You may want to use some or all of these. I like the slotted mandrel with emery cloth (very coarse) first. Try to hold as flat as you can, not following your former pattern, working at different angles. Don't turn too fast as sometimes heat will make the aluminum wash. When this is looking good and you are satisfied with the basic surfaces, go to the finer grit (approximately 180, if you desire a smoother finish). Run an opposite pattern, and in the final stages flap the surface with the edge of the emery cloth, tearing off the ends as they become frayed (go to the finer grit if desired). Always go in and out of ports with the tool stopped.