Do not go by the threads or the tip of the electrodes, go by about 1/4 way down the ceramic for a color guide. You want a nice tan color to them. Blacker is richer, whiter is leaner.
If you get a tan color but only on half the ceramic, (around the ceramic, not up and down it) try indexing your plugs. This is seating them, using a small washer sometimes for correction, so that the actual gap is pointed directly at the combustion chambers. Old moto-x trick, gives a more even burn from the plugs.
