Mercury timing adjustments

[Carl]

I am attempting to check and adjust the timing (as needed) of my Mariner 150 with the help of a shop manual and the 1st item is to check and adjust the timing pointer. It describes getting #1 cylinder to TDC with the help of a dial indicator. Then rotating the flywheel ccw until the dial indicator needle is 1/4 turn beyond the 0.462" mark on the flywheel timing decal. Then rotate the flywheel CW until the dial indicator needle reads exactly 0.462" Then check the timing pointer alignment and the pointer groove should align with the 0.462" mark on the flywheel timing decal. If not, then adjust the pointer to correctly align with the .462 mark.

Now - maybe a stupid question, If #1 cylinder is TDC shouldn't the timing pointer be pointing to 0 degrees on the timing mark and the make this step much easier?

Please advise as to why such detail with a dial indicator. What is the significance of the 0.462" mark?

Thanks

Carl