1963-1973 Mercruiser all Engines and Drives Service Manual Books 1 and 2, Page 39Get this manual
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IGNITION TIMING TIMING MAR LOCATION
Figure Timi Tab on V-S Engine
J Hark ing.s tabs arc in .rem nlswith rreates number of marl:in,!! all"s ide oJ "0"AI BTD set tlllgs fa ll 011 I,h"