2 barrel to 4 barrel

To answer the original question, changing only the carb from a 2 to 4bbl [ & a 4bbl intake ], I agree with the others about 15-20 hp. Very little if any benefit at the lower end. However, using a high signal carb that has annular pri boosters like the Edel 500 AVS2 would would probably add some low end tq as well.