Deusenburg walking beam engine

In the early development of gas engines the valve-in-block layout was a natural but the large surface area of the combustion chamber formed by sidevalve and T heads led some designers to expensive overhead valve and troublesome overhead cams.

 This was Deusenburg's mid-teens solution, the cylinder layout is vertical, but the valves were lined up horizontally into in a tall narrow combustion chamber. The cam was still located in the block, and large "walking beam" rockers actuated the valves. I assume the large reciprocating mass kept engine speeds low though the engine was known to work well. More here

Griffith Borgeson, The Golden Age of the American Racing Car, Bonanza Books 1966