I have a 1967 chevy pickup,with a 350 v8 20,00 miles on engine. Had this problem from the day I bought the truck. just paid $700
for a Holly double pumper 4776 carburetor 650 cfm. Mechanic has left town. Carb replaced 1000 MILES AGO. At IDLE the engine is LOPING; Will stall at idle unless rpm are increased. CHANGED OUT VACUUM LINES; REAR PORTS IN CARB. ARE FLOWING FUEL AT IDLE; How can I adjust this fuel flow ? Black soot at tail pipe.
If engine rpm is increased black soot droplets are blown out. Engine rpm gauge fluctuates when truck is driven.

for a Holly double pumper 4776 carburetor 650 cfm. Mechanic has left town. Carb replaced 1000 MILES AGO. At IDLE the engine is LOPING; Will stall at idle unless rpm are increased. CHANGED OUT VACUUM LINES; REAR PORTS IN CARB. ARE FLOWING FUEL AT IDLE; How can I adjust this fuel flow ? Black soot at tail pipe.
If engine rpm is increased black soot droplets are blown out. Engine rpm gauge fluctuates when truck is driven.