The 1971 Ford Mustang Boss 351 is the center of attention in this edition of Muscle Car Milestones. The 1971 Ford Mustang Boss 351 was a one-hit wonder that inadvertently found itself the odd man out. With elimination of the Boss 302 and Boss 429 during the previous model year, the new Mustang Boss 351 had some big shoes to fill. However, this new Boss proved its merits and was one of the last great Mustangs created during the classic muscle car era. Let’s see what makes the 1971 Ford Mustang Boss 351 a muscle car milestone.

By 1971, the muscle car was on life support. Between Uncle Sam implementing rigorous emission standards and Big Insurance instigating lofty insurance premiums on muscle cars, it was only a matter of time before performance started to wane. The 1971 Ford Mustang Boss 351 was a last gasp effort by the Blue Oval to keep performance alive during this time of transition.

Ford debuted the 1971 Ford Mustang Boss 351 on November 21, 1970 at the Detroit Auto Show. Those at the show got to see a Mustang that put on a few hundred pounds, was 2.1 inches longer, and 2.8 inches wider. The Boss 351 also featured a wider track of 61.5 inches up front and 61.0 inches out back. Attendees also witnessed a new Mustang with a long, flat hood and a back window that was only 14 degrees from horizontal.

The 1971 Ford Mustang Boss 351 was based on the new SportsRoof design that debuted during the 1971 model year. Standard styling cues include a black chin spoiler, “Boss 351” badging on the front fenders and rear panel, and unique body striping. The Boss 351 also featured a honeycomb grille with fog lights, dual body-color mirrors, and Magnum 500 wheels with Goodyear Polyglas F60x15 tires.

Inside the cockpit, drivers are treated to high-back bucket seats, a center console, and instrumentation including an 8,000-rpm tachometer, oil temperature, ammeter, and water temperature gauges. Optional interior choices include the Deluxe interior with Comfort-Weave woven inserts and the coveted Mach 1 sports interior.

The heart of the Boss 351 is an R-code 351 cubic-inch Cleveland V8 rated at 330 horsepower and 370 lb.-ft. of torque. This engine features high-flowing cylinder heads, smoothly contoured ports, and a polyangular combustion chamber. This engine also features components such as a 750 cfm Autolite four-barrel carburetor, high-strength aluminum pistons, and magafluxed connecting rods with high strength nuts and bolts. And while several muscle cars suffered from lower compression in order to run on unleaded gas, the Boss 351’s engine had a surprising compression ratio of 11.7:1. The aforementioned polyangular combustion chamber and stroke measurements that were one-half inch greater than the 302 V8 are partly to blame. This powerplant was coupled to a Toploader four-speed manual transmission with T-handle Hurst shifter. Drivers could choose between close and wide ratios.

Speaking of performance equipment, the Boss 351 packed quite an arsenal. Highlights include competition suspension with staggered rear shocks, a dual ram induction package, and dual exhaust. A Traction-Lok nine-inch rear end with 3.91:1 gearing and power front disc brakes were also standard performance equipment.

How well did the 1971 Ford Mustang Boss 351 perform? Motor Trend put the Mustang Boss 351 to the test against the Mustang Mach 1 429 in the January 1971 issue. Even though the big block Mach 1 outgunned the Boss 351 by 40 horsepower and 80 lb.-ft. of torque, the Boss 351 gave the Mach 1 a major beatdown. The Boss 351 could sprint from 0 to 60 in 5.80 seconds, compared to the Mach 1’s time of 6.50 seconds. Adding insult to injury, the Boss 351 ran the quarter mile in 13.80 seconds at 104 mph beating the Mach 1’s time of 14.61 seconds at 96.80 mph.

Ford built a mere 1,806 Boss 351 Mustangs during the 1971 model year, making them instant collectibles. The 1971 Ford Mustang Boss 351 was also the first Mustang with a base price over $4,000. This base price even surpassed the 1971 Mach 1’s base price with the 429 Cobra Jet engine.

The 1971 Ford Mustang Boss 351 was one of the last performance-oriented Mustangs created before the death knell rang on the classic muscle car. Sadly, the Boss 351 wouldn’t continue into the 1972 model year. The good news is this one-hit wonder left its mark and is still sought out by Mustang collectors today.