timing

[brucem101]

having never used a timing light i have to ask this---a 115 78' merc outboard, has timing numbers on the flywheel and a fixed set on the motor. if i want to set my timing at 21 degrees do i allign the 21 on the flywheel with the stationary -0-, or allign 21 degrees with the 21 degrees fixed position?

[boats.net]

There should be a timing pointer on block, you align the 21 deg. mark with pointer.