1985 OMC 65, 100 and 155 HP Models Commercial Service Manual, PN 507450-D, Page 49Get this manual
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Selecting Propeller Since propeller pitch and diameter determine motor rpm at given boat speed, the importance of propeller selection cannot be overemphasizedThe operation and performance of the motor depend on itA tachometer is required to check motor rpm propeller should allow the motor to run at the top limit of its full throttle operating range with the lightest load that boat will carry(See Specifications, Full Throttle Operating Range If such propeller is selected for this special application, rpm loss at full throttle will not, in most cases, drop below the limit of the operating rangeThere are instances where one propeller cannot cover the complete range of boat applications; for example, from water skiing to high speed performanceI such cases it may be necessary to change propellers to suit each particular situation(Light load, higher pitch propeller; heavy load, lower pitch propeller Remember, if the motor operates below the recommended full throttle rpm range, the motor is laboring and power and efficiency are being lostWhen the motor is equipped with rpm limiter power pack, operating the engine above the recommended fu II throttle rpm range will cause the engine to develope mis-fire conditionIn such case, install higher pitch propellerTo prevent accidental starting of motor, disconnect statorcharge coil assembly to power pack connectors and shift motor into neutral when replacing propeller