Snap-on used to make a GO/NOGO feeler gauge set that was useful for running adjustments. The first 1/2" of the feeler was the correct thickness, and the rest of the blade was .002" thicker. Of course, the tool was very expensive, and most mechanics didn't bother buying it. Feeler gauge blades were sold individually by the parts truck guys, so when the more common ones got battered too badly to use they got replaced instead of buying a whole new set. Stopped engine adjustment after warm-up was much more accurate.
Jerry
