Re: How Important is OMC Ignition Timing?

[legendre]

quote Phil B:

Timing of the spark is only a range relative to TDC. (…) Timing of the spark relative to TDC at a given throttle position (& carb butterfly position) controlled by the “link and sync” adjustment cam.

Sure.. but what defines the upper & lower bounds?

Let’s just ignore the fact that the ignition timing changes with mag lever / throttle position.. and view the motor at full speed, max RPM and hence, max ignition advance.. just as with any motor, running at full speed and full advance.

What defines that final, high-RPM timing angle figure? Is it a certain, factory-specified number of degrees BTDC (as with every other engine), or just wherever it happens to end up, if ‘timing’ is set for the moment of max spark energy – on an OMC?

Are you saying that OMC timing theory is literally different from virtually every other engine out there? Every other engine I’ve encountered has ignition timing specified in degrees BTDC – but per you, and those who agree with you, that’s out the window. You’re claiming that the spark should fire at the moment of greatest energy, and the actual ignition event just falls where it may.

I don’t buy it. And again, ask yourselves: Why does the OMC timing tool exist?