Originally Posted by GearNut
Cruise, electricity travels at 186,282.397 miles per second. Changing the gap on the spark plug a few thousands of a inch will not affect the timing.
Perhaps you were thinking of changing the gap on the points of a traditional points/breaker style ignition? Changing the gap on that will definitely affect the ignition timing.
I note that it may be the case that a larger gap could cause the spark to wait fractionally for the voltage to climb higher to jump the gap - in fact, a too large gap may cause the spark to wait forever.
Also, this may affect the quality of the spark in terms of its ability to start a good burn.