Re: How Important is OMC Ignition Timing?

[legendre]

quote Phil B:

The timing tool, or “gapping the points” exist to adjust timing of the spark (the points opening) relative to the position of the coil & magnet.

And in all other instances I’ve ever encountered, the timing is set relative to crankshaft position – in terms of degrees BTDC.

quote :

Timing of the spark relative to TDC (advance) is controlled by the position of the magneto plate (which also controls the throttle via the magneto plate cam)

Again, this is a red herring. Ignore the fact that the timing follows the throttle lever position.. and answer this:

What determines the final timing advance figure, when the engine is running at full speed? Is it simply a matter of where the spark is strongest, or where the spark is most appropriate to the crankshaft position in terms of degrees BTDC (as with +every+ other design)?

And no one has answered the big question – Why does the OMC timing tool exist, when the "timing" is simply a matter of aligning the magnetic TDC with the coil’s pole shoe? Why would you need such a tool, when the relationship you desire can be set with a ruler, or with a set of factory-applied marks? Does the OMC timing tool index on the magnet position, or on the crankshaft position?

(Hint: It’s because the magnetic TDC isn’t what we’re after… it’s a particular crank position, as with every other timing spec.)