Running rich possibly?

I have an 88 lude Si that I have just put about 1500-2000 bucks into. My car shoots carbon out of my exhaust at times. Along with this is the fact that it has new plugs and they are black at the tips after less than 500 or 800 miles. I'm wondering what would cause this to occur. I had the head re-done and replaced some other stuff on the car. Is timing the only thing that would cause this? or is there another culprit that it could be? please let me know if you know anything.

Drew

Try SeaFoam. and put in new spark plugs.
http://www.seafoamsales.com/motorTuneUp.htm

I have an 88 lude Si that I have just put about 1500-2000 bucks into. My car shoots carbon out of my exhaust at times. Along with this is the fact that it has new plugs and they are black at the tips after less than 500 or 800 miles. I'm wondering what would cause this to occur. I had the head re-done and replaced some other stuff on the car. Is timing the only thing that would cause this? or is there another culprit that it could be? please let me know if you know anything.

Drew
www.halmeter.com