Workmonster Racing Engines     |   home                      Porting 011 Shot of bowl work. Notice the vane behind intake guide. It is now aligned with the bias of the port, much different than stock.     The guides are put in and honed to size. The port throat is then bored to the proper size. This is determined by valve size, and valve job angles and widths.    Intake: 30 degree top cut, as narrow as possible to maintain integrity of the 45degree cut, which is .040-.055 wide, depending on the head's use. O.D. is .005-.010 less than head size of valve. Bottom cut is a 60degree deal, .100 wide. After that, a 90deg cut is made, dropping straight into port for .100. This cut was actually made with the boring tool mentioned above.     Now the whole bowl is enlarged to match this new seat. The valve guide is narrowed and streamlined as shown, the bowl is raised and widened, and the short side is ground with smooth curve up to the existing high point in the floor. The high point is now pretty close to the turn, so the curve is fairly tight, but that's the way it has to be. Put a valve in to the guide upside down, then use inside dividers to make sure the turn actually starts at the bootom of the .100 wide 90degree cut, and no material is overhanging. No material should be closer to the valve stem than the 90dgree cut.