1985 Mercury Outboard V-300 V-3.4L Shop Service Manual, Page 110Get this manual
M elturtng Pi,ton Roundnell Piston has barrel profi le shape and is not true diameter
IUsing micromete r, measure dimensionA" al locati on shownDimension "A" shou ld be as indicated in chart foll owing
DimensionA" et Piston Pin Right Angle0
Sta nd ard piston
Dimen sion "A"
3.732 .001