A mounting assembly for a stern drive engine including a mounting base, an engine mounting foot or bracket for securing an engine to a watercraft, and a lock ring for securing the engine mounting bracket in a constant position relative to the mounting base. The mounting base includes a threaded mounting bolt to receive a first adjustment nut, the engine mounting bracket, the lock ring and a second nut. The bottom surface of the locking ring engages a top surface of the engine mounting bracket with a downwardly extending arm or arms of the lock ring extending through an aperture in the engine mounting bracket to engage the first adjustment nut. The threaded bolt of the mounting base extends through apertures of the engine mounting bracket platform and mounting ring, and a second nut engages the top surface of the lock ring, preventing rotation of the first adjustment nut, and ultimately limiting movement of the marine stern drive engine.