Mercury Mariner Outboard 225 3 Litre Service Manual 1994, Page 66Get this manual
Timing Pointer Adjustment '
2Remove all spark plugs and install Dial Indicator (91-58222Al) into No1 cylinder (top cylinder, starboard bank)
Engine could start when turning flywheel to check timing pointer adjustmentRemove all spark plugs from engine to prevent engine from starting1Remove flywh eel cover by sliding back and lifting cov-
er in simultaneous motionRemove carburetor air attenuatar by releasing two latches at bottom of attentuator
a Dial Indicator Installed in No1 Cylinder
3Turn flywheel in clockwise direction until No.1 piston is at top dead center (TOC) Set dial indicator at "0" (zero) and tighten indicator set screw4Turn flywheel counterclockwise until dial indicator needle is approximately 14turn beyond .526", then turn flywheel clockwise so that dial indicator reads .526" (11 .7mm) exactlyReposition timing pointer (if necessary) so that timing pOinter is aligned with .526" mark on flywheelTorque pointer attaching screw to 105 lbin(11 .8Nm)