thanks for the reply Jerry. We are priming the carb with unleaded gasoline, about a 2 second shot from an air assisted fuel sprayer. Then its right on the 94% nitromethane fuel as soon as it fires. And we are not changing the plugs for warm up. Unfortunately niether one of us has delt with nitro and its a huge learning experience for us. We know just about enough to get us in trouble (obviously).