The carburetor sitting on your vintage Mustang can be a finicky device. It has minute passages that air and fuel travel through to feed the engine the fuel it demands based on load, rpm, and so forth.

Holley came out with the first modular carburetor, the 4150, back in '57. Today, Holley still makes the 4150-heck it even makes hopped-up versions for everything from drag racing to rock crawling.

While the carburetor is generally acknowledged as the most important part of your engine, it is at the same time the most ignored and misunderstood. It usually just sits patiently atop the engine with ...