After this minor porting, Tom then cut the valve job on a Serdi valve grinding machine. The Serdi uses a floating cutting platform and a floating cutting head that makes fast and precise valve jobs a snap. A proper valve job is a key contributor to good flow so a proper valve job is a must. With the Serdi, Tom cut our 45 degree exhaust valve seating surface larger to accommodate the larger valve. Tom uses cutters to make a 70 degree or so throat cut up to the 45 seat and a 30 degree top cut to unshroud the 45 seat into the chamber.
|Tom then uses a burette to measure the amount of water that he can fill the combustion chamber to through a hole in the plexiglas plate.|
After cutting the valve seat angles, Tom then hand blends the 70 degree cut to the 45 seat and the port wall in a smooth radius. The 30 degree cut is blended from the seat to the chamber in a smooth sweep as well. This makes for an unhibited path for the incoming and outgoing intake and exhaust charges as the valve opens and closes.
|This operation is performed with care to get all of the air bubbles out. That’s the reason why clear Plexiglas is used.|
After the port work and valve job are done, Tom then hand finishes the combustion chamber, grinding back areas where the seat and the combustion chamber have steps and where the outer wall of the combustion chamber comes really close to the valves potentially shrouding them and blocking flow.
|If you didn’t take chemistry 101, when using a burette, use the bottom of the meniscus (the water will curve due to surface tension in the burette, the meniscus is the edge where the water climbs up the sides of the glass cylinder) to determine how much water has been added to the chamber.|