1985 OMC 65, 100 and 155 HP Models Commercial Service Manual, PN 507450-D, Page 53Get this manual
Adjustable Stern Brackets The adjustable stern brackets allow you to position the motor on the transom to obtain the best possible performanceProper height adjustment of the stern brackets can, depending upon boat size and weight, increase the top speed performanceIf it was necessary to use alternate location holes when mounting motor to transom, the stern brackets are no longer adjustableAPrimary Locations BAlternate Locations 1After the correct propeller has been selected, test run the boatIf no ventilation is evident, raise the stern bracket one position r;:;:;:] When changing position of stern brackets, it is only necessary to remove the upper bolts; the bottom bolts need only be loosenedSecure the brackets, and test for improved performance2Continue to raise the motor (one position at time) and check for improved performanceThis raising and checking should be continued until excessive ventilation occurs in turnsExcessive ventilation will result in loss of top speed and marked increase in motor speedThe final setting should be one position below the setting where the excessive ventilation occursAfter final setting is reached, check for interference between "boat mounted" remote steering system parts and outboard motor parts or any other items in the transom areaTilt the motor fully into the boat and turn the motor through its full rangeFailure to ensure no contact may result in steering system parts being broken or weakened should the motor strike an underwater object and tilt rapidly into the boatSudden steering control loss could occurIn most instances, the propeller selected earlier will still be correctHowever, on light boats different propeller may be necessaryA fu II throttle tachometer check wi II insure that the motor is still operating within the recommended limitsSee Propeller Selection3""