Tinkering with used spark plugs has a placebo effect- - - - -it makes you believe you're actually doing something. The places a possibly shorted plug would need to be cleaned can only be reached with a sandblaster, and even if that's done, I've seen perfectly-clean-looking plugs that wouldn't fire- - - - -the voltage was leaking down the surface of the insulator instead of jumping the gap. Now, one proviso here- - - -those situations were 40-something years ago, and the plugs had been flooded severely with lead-additive gasoline. Our therory after a new set of plugs made an engine start that we had been fighting with all day was that the flooding had deposited a layer of conductive lead compounds on the insulator that effectively shorted the porcelain insulated center electrode to ground. At any rate, a set of new plugs fixed the problem, even after the old ones had been thoroughly sandblasted.
Jerry
