The secondary firing voltage difference a .005" change in plug gap might- - - -if the alignment of the planets is just right, and you use the proper voodoo spells from Marie LeBeau on a moonless night down on the bayou- - - -maybe could be measured on the firing line of an accurate oscilloscope. Of course, a tiny bit of difference in the mixture swirl pattern around the spark plug tip would probably make the same amount of voltage difference with identical plug gaps!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!