An engine

A piston and connecting rod assembly for an internal combustion engine comprises a piston (31), a connecting rod (34), and a spring (39). The connecting rod (34) has a first end operatively associated with the piston (31) for movement therewith, and a second end connectible to a rotary output shaft. The spring (39)acts between the piston (31) and the connecting rod (34) to bias the connecting rod away from the crown (31a) of the piston.