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This is one of the Williams Brothers early steam engine designs from 1946. This was designated Model 1610 and was four cylinder opposed 3 ½ x 3 ¾”. It is a uniflow with poppet valves. Of interest is the means for changing the intake valve timing. It appears to be the same design as used on the Ford V-8 conversion, also made in 1946, Model 1648. This was a high speed engine.

The exhaust valves are poppet valves.  The intake valves are cam operated piston valves with very clever multi-port admission ports.  This allows the piston to move less than a quarter of an inch for full opening to closing.

It appears that the intake valves are cam operated piston valves.  The auxiliary exhaust valves are very small poppet valves. 

Photography by Derek Peters