The L-head engine, also called flathead, is an internal combustion piston engine whose valve configuration resembles the letter 'L' upside down. This type of four-stroke machine had both inlet and exhaust valves located on one side of the engine block. These are driven by push-rods actuated by one single camshaft, which allows the opening and closing of the valves at the proper time.
The L-head engine was commonly used in cars in the 1930s, 1940s, and early 1950s. They were very popular with hot rodders and racers. Today, it is employed in lawnmower, generators, and other industrial engines. Although L-head engines are less expensive to built, they produce more smog because of the high amount of surface area exposed to unburned fuel. They are also limited in their compression ratio and valve lift. Increased valve lift needs more clearance in the combustion chamber, which lowers compression.
Below, the photo shows an L-head Studebaker engine, with the cylinder head removed. You can see where the valves are situated in the block and how they are arranged.
A schemtaic drawing, showing the valve and rod configuration of an L-head engine.
