Seems that the general problem with carbs is running rich, my problem is running lean.
Engine runs fine and idles well (O-320 A2B) this only came to my attention when I pulled the plugs to do blow by`s. This is a new engine that was locally overhauled, and has around 35 hrs on it. On rear cylinders - 3&4 the plugs have a distinctive white residue, the forward cylinders 1&2 have a normal grayish/Brown residue .I have done the normal visual checks for intake leaks on Clamps , hose condition ect also tried Supercub MD suggestion with the grease on the intake joints but nothing obvious . there is no primer system fitted ,and have checked the blanks fitted for possible leaks , I have been running full rich in this condition ,Our field elevation is around 5000ft which also means that this engine should be more on the rich side . Carbs is the MA 4SPA but the pn is 10-3678-11 Seems it should be a -12 could this be my problem? Is there a reason for the rear cylinders running leaner than the forward cylinders?