Internal combustion engines

Claim 1

In an overhead valve internal combustion engine, including an engine block having at least one cylinder in which a piston is reciprocable along an upright axis between upper and lower positions, said engine also including a head connected to said block to overlie the upper end of said cylinder and to cooperate therewith to form a compression chamber, and intake and exhaust valves mounted on said head for reciprocation along respective axes, each of which is at the same acute angle to the axis of reciprocation of said piston, each of said valves having a flat head movable into said compression chamber when the valve is open, the improvement for increasing the compression ratio of said cylinder, comprising: a separate metal plate adapted to be attached to the upper face of said piston, said plate being of a peripheral size to lie within the confines of the piston periphery and of a thickness to extend upwardly from said piston face a predetermined amount, said plate having an inclined surface which, when said plate is attached to said piston, is disposed in confronting relation with said valve heads to provide adequate clearance for the latter during opening movement of respective valves.