FORMING CYLINDER BORES

摘要

Cold distortion of an engine cylinder bore (2) is caused by the tightening of bolts (4) which secure the cylinder head and/or the crankcase to the engine block (10). Hot distortion is caused by uneven heating of the bore when the engine heats up to its normal running temperature. A method of forming an engine cylinder bore (2a) which is circular (8) in cross section when the engine is running at its normal operating temperature comprises machining the bore (2a) at ambient temperature to have a non-circular cross section so that hot and cold distortion cause the bore (2a) to become more nearly perfectly circular in cross section.