Buick introduced a factory deuce two-barrel carburetor set-up in 1941. This lasted for 2 years-'41 and '42. It didn't return after WW II. In 1952, the Roadmaster, which had the larger 320 ci straight eight, received a four-barrel carburetor. At that time, the factory engineers determined that the bottom end couldn't keep up with the top end.
The straight eight, hooked to a manual transmission, could slow to well below 10 MPH in 3rd gear and accelerate without having to shift to a lower gear. Folks that bought Buicks loved that smooth, torquey engine. It just couldn't keep up with the horsepower race that was starting in the late '40s-early '50s.