Originally the engine was fitted with a hot tube on top of the valve chest. The Waldensians used to make a pine pitch fire around the hot tube. At some point a spark plug and buzz coil were retrofitted to the engine. In the outside face of the valve chest can be seen the original poppet cylinder and valve that moved out on the power stroke. Through the linkage a small pin was inserted into the skip mechanism, allowing the exhaust valve to be opened.
Photo by Curt Holland