The Foden High and Low pressure valve covers were supplied as a one piece casting, so needed to be cut. There is very little room for error as the casting are already cast dimensionally under size. So a minimum clean up around the edge, could only be achieved. The castings were already 1/32" undersize before clean up, so minimum amount removed with cast witness marks left around edge. The castings should also be 3/16" thick but if this had been achieved the details would be lost on the casting. so opted to make 1/4" thick.
![](resources/Valve_chest_covers/Datum.jpg.opt650x654o0%2C0s650x654.jpg)
![](resources/Valve_chest_covers/Datum%202.jpg.opt650x866o0%2C0s650x866.jpg)
![](resources/Valve_chest_covers/Fly%20cutting%20LP%20cover.jpg.opt650x591o0%2C0s650x591.jpg)
![](resources/Valve_chest_covers/Spot%20drilling%20HP.jpg.opt650x866o0%2C0s650x866.jpg)
![](resources/Valve_chest_covers/Spot%20face%20HP%202.jpg.opt650x866o0%2C0s650x866.jpg)
![](resources/Valve_chest_covers/Spot%20drilled%20LP.jpg.opt650x866o0%2C0s650x866.jpg)
![](resources/Valve_chest_covers/Spot%20face%20LP%202.jpg.opt650x866o0%2C0s650x866.jpg)