Abstract: An internal combustion engine has a carburetor and cylinders, each cylinder having two fuel/air intake ports, and also provided is a first manifold runner system having a fuel/air intake end communicating with one barrel of the carburetor, and a fuel/air delivery end communicating with one of the fuel/air intake ports at certain cylinders, and a second manifold runner system having a fuel/air intake end communicating with another barrel of the carburetor, and a fuel/air delivery end communicating with the other of the fuel/air intake ports at engine cylinders.