The .060 (and .080) plug gaps were there in the vain hope that there just might be something flammable between the spark plug electrodes when the plug fired. Once catalytic converters came into general use, the fuel mixture could be richened up enough to get a more consistent cylinder burn without a plug gap the mechanic could throw his hat through. I owned a shop in California during the bad old days when the manufacturers were jumping through all the hoops that Uncle Sam and CARB were dreaming up- - - - -and trying to meet impossible fuel economy standards at the same time!

"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!