1985 OMC 65, 100 and 155 HP Models Commercial Service Manual, PN 507450-D, Page 52Get this manual
Motor Installation Do not overpower by using motor of horsepower (kW) range higher than that prescribed on the certification plate on the boatOverpowering boat can cause instability
Transom Height Proper transom height is essential to obtain maximum forward thrust from the motorIf transom is too high, propeller slippage (ventilation) may resultThis would affect general performance and proper cooling of the motor
Models 65
Transom Height 495-508 mm19-12" to 20") 495-508 mm (19-12" to 20") 622-635 mm (24-12" to 25")
100 and 155 Long Shaft
155 Extra Long Shaft
If transom is too low this will produce drag resulting in some loss of speed and undesirable sprayI nterference from the keel is frequently the cause of propeller ventilationBy merely tapering the keel this can be eliminatedUse special nuts, bolts and washers shipped with motorDo not switch with other parts wh ich may look the sameTighten nuts firmlyCurved Transom Curved transoms do not lend themselves to proper mounting of outboard motorsSuitable Shims Must Be Used to obtain flat surface for mounting of these motors to insure the proper engagement of the motor to the boat transomThis will insure that no part of the motor mounting assembly or the boat will be damaged or that the motor will not come loose from the transom when maximum power is applied_ Contact boat manufacturer for assistance if necessary