Working on a 17058213bjb. 2237. I have completed many of the upgrades listed in the book. New bushings, throttle plate timing, choke removal, .040 idle tubes installed, notches in upper air flap, da secondary metering rods .0440 on F hanger. Down channel is.0490. 42 B primary metering rods measure .0260. 70 mains. Main air bleeds in air horn are.0490. Idle screw orifices are .085. Described unit was on fresh rebuild 4.040x 3.75 sbc. Afr 180 Al. heads, 260 cfm @.500 int, 210 cfm @.500 ex. Cam is HR with 221 int @ .050, 223 ex @ .050 with .510 int and .492 ex on 108 lobe centers. CR is 10.6 with tight quench. Pulled 13” hg.At idle.Carb ran well to my knowledge until removal of engine to perform inspections and discovered what I would consider excessive soot/ carbon buildup on plugs, combustion chambers, and pistons. Exhaust tips were very sooty as well. Described units reside in 3400 lb. Camaro with th400 backed to a gearvendor overdrive unit. 3.90 axel with 30” mickeys. 3000 stall. Cruises nicely at 2200rpm and 55mph. Upon further investigation and reading this carb was on p/u 350. No apt. On baseplate. Main air bleeds protrude into air horn,probably adversely affecting cfm flow. Comments in book state this carb can be hard to tune. I am inquiring as to what can be done to fix what I am suspecting as overly rich off idle conditions, or any other mods to start with. Car idled great and the secondaries come in like like a 12 gauge. Timing was 34 btdc. @ 3000 all in. Is it possible to install your APT mod in this unit.
