duane 3, the correct way to read a plug is to run wot and immediately shut down. If it's still black, then and only then would I say it's running rich. You can also have a wideband O2 sensor put in the exhaust and monitor A/F ratio. The fact of the matter, running a bit rich is safe as is running a bit retarded. A lean condition can kill your motor as can having the timing advanced too far. Just saying.