Mercury Mariner V-250 V-275 Outboard Service Shop Manual 1990, Page 307Get this manual
Securing Outboard to Boat Transom IMPORTANT: If boat has thru lilt tube steering, route sleering cable end thru tilt tube before bolting out board to transomRefer to "Steering Cable and Steering link Rod Installationfollowing
AWARNING
Before operating, outboard(s) MUST BE SECURED to boat transom with four 1 indiameter bolts and locknuts, as follows: bolts must be installed thru upper mounting holes and bolts thru lower mounting holesInstallation must be water-tight, and outboard should be checked for tightness on the transom during operationFailure to bolt outboard to transom (using bolts and locknuts, as shown) may result in damage to boat andl or loss of outboard and possible injury to occupants of boat
Temporarily fasten outboard to transom with two 4-112 in(114mm) long mounting bolts, flat washers and locknuts, using top holes in upper set of transom bracket mounting holesUsing top holes in lower set of transom bracket mounting holes as drill guidesdrill two 17 32 in (13.5mm) diameter holes perpendicu lar to and thru transomRefer to "Determining Recommended Outboard Molor Mounting Height", preceding and position outboard