missing

[j.honor@comcast.net]

74-tr6; ok installed rebuilt dizzy, set @ 12 degrees; with petronix; idling 
around 1000; idle is balanced between the 2; installed rebuilt carbs with mid 
point on mixture was quite rich-sooty balck; still getting to right color, 
still abit rich =plugs sooty-but improving; engine is missing around 2000-3500, 
thoughts? keep advancing +12 degrees?any other baseline steps to consider?also 
new fuel filter.