The 1971 Mustang was larger than its predecessor in almost every dimension. In 1971 the Mach 1 started with a base engine of the 302ci based Windsor motor, with a 2 barrel carburetor. The lineup of engines included four 351 Cleveland engines: The 2-V, 4-V, the C.J.(Cobra Jet) and H.O.(BOSS 351). The H.O was canceled after mid-year 1971, and shortly thereafter the low-compression 351 ‘Cobra Jet’ became available. The lineup topped out with two 429ci options, the CJ (Cobra Jet) & SCJ (Super Cobra Jet). Mach 1s, as well as all other Mustang models (except the BOSS 351) were optionally available with the CJ and SCJ motors. The SCJ came with a drag pack V or W code rear gears, oil cooler and a different rotating assembly. 429 Super Cobra Jet engines used a Holley 4-barrel carburetor, while the Cobra Jet engines made do with a GM-sourced Rochester Quadra-Jet 4-barrel carburetor.