Carb Adjustment

[timfboston@aol.com]

I set the mixture on my carbs (SU HS4) using the colortune.  The engine revs 
fine in neutral, but when I try to drive it hesitates with no power from 
2000-3500 RPM.  If the choke is pulled out (with the engine warmed up) the car 
runs great with lots of power.  This makes me think that I need a richer 
mixture, but the spark plugs are sooty black to make me think that it is too 
rich.  Any suggestions?
 
Thank you,
 
Tim
1971 MGB