An overhead valve engine, abbreviated and sometimes called a pushrod engine, is a piston engine whose valves are located in the cylinder head above the combustion chamber. This contrasts with flathead
1894 prototype overhead valve Diesel engine
1904 patent for Buick overhead valve engine
1918 Buick 242 engine, right side.
V8 engine (with intake manifold removed), showing the camshaft, pushrods, and rockers
A flathead engine, also known as a sidevalve engine or valve-in-block engine, is an internal combustion engine with its poppet valves contained within the engine block, instead of in the cylinder head
A crossflow T-head sidevalve engine
1915 Cadillac flathead engine block