1990 Johnson Evinrude "ES" Colt/Junior thru 8 Service Manual, P/N 507870, Page 34Get this manual
Propeller Selecting the correct propeller for each engine and boat combination will ensure good engine service life and good boat performanceA propeller must be carefully selected to match the engine boat combination, the application, and the anticipated load in the boatSelection of the wrong propeller could reduce engine service life, affect boat performance, or cause serious damage to the powerheadOMC propellers available for these engines are listed in the Propeller and Steering Connector Guide and the OMC Parts and Accessories Dealer Catalog Procedure The propeller selection process is very important to the engine service life and to boat performanceProceed carefully and thoroughly while considering the following points: During the engine break-in period, only run the engine at wide-open throttle for brief periods of time to verify full-throttle RPM You must use an accurate tachometer to determine the engine's full-throttle RPM as you test various propellers Select propeller that suits the customer's application and allows the engine to run near the midpoint of the full throttle operating range when the boat has normal load in itRefer to Engine Specifications, this section To compensate for changes in boat loading, the engine's full throttle RPM must be verified periodically Occasionally, one propeller will not cover wide range of boat applicationswater skiing to high speed performance boatingIn such cases, it might be necessary to have propeller for each situationIf the propeller blades have too much pitch, the engine is operating below its normal range at full throttlepower is being lost, and powerhead damage could occurIf the propeller blades have too little pitch, the engine is operating above its normal range at full throttle and damage from overspeeding could occur