2001 Mercury Mariner 50-60HP Factory Service Manual, Page 199Get this manual
CYLINDER HEAD
Free Length "a" Tilt Limit "b"
1.491-1.569 in(37.85-39.85 mm) Less than 0.060 in(1.7 mm)
VALVE SPRING
Compressed Pressure (Installed) Intake Exhaust Tilt Limit (IntakeExhaust) Dirof Winding (IntakeExhaust) Warp Limit
19.822.0 lbs(9.010.0 kg) 19.822.0 lbs(9.010.0 kg) 0.043 in(1.1 mm) Left Hand 0.004 in(0.1 mm)