One of my skills is repairing, rebuilding, and restoring knock engines. A knock engine engine is a laboratory test apparatus that rates the octane value of gasoline. Octane is the amount of anti-knock property of a fuel. This custom one cylinder engine has a cylinder head which can be raised and lowered at will thereby changing the compression ratio of the engine. It can then be precisely determined when a gasoline will spontaneously ignite resulting in a wavefront which collides with the wavefront of the spark ignited ignition. This collision is called knock and is the pinging sound you here when you run a vehicle on bad gas.

This gallery has pictures of the total apparatus and a crankcase in various stages of overhaul.