Though less fiery than the Boss models it replaced, the Boss 351 fastback was the quickest, most roadable '71 in the Mustang stable.

The 1971 Ford Mustang Boss 351

The 1971 Ford Mustang Boss 351 listed at $4101 on its belated debut at the November 1970 Detroit Auto Show. Save model badging and a chrome front bumper, it looked much like the 1971 Ford Mustang Mach 1.

Indeed, it could have been badged "Mach 2," as many of its standard performance goodies were available for the more affordable Mach 1. For example, though both included the stiff competition suspension, the Boss came with F60-15 tires instead of E70-14s, plus power front-disc brakes ($70 otherwise), wide-ratio four-speed gearbox with Hurst linkage, 3.91:1 Traction-Lok axle ($48), functional hood scoops, dual exhausts, heavy-duty battery and cooling system, rear spoiler, electronic rev limiter, and gauge package.

The significant difference was the Boss 351's very special engine, an exclusive High-Output (HO) 351 Cleveland with four-barrel (4V) carb, soaring 11.0:1 compression and 330 horsepower.

A special High-Output 351 V-8 with premium internals delivered a solid 330 bhp through a four-speed manual gearbox with Hurst shifter.

Touted by Dearborn as "the best all-around performer in Ford production-car history," the new Boss was the fastest of the '71 breed -- and the most roadable right out of the box. Chuck Koch, who tested a trio of Mustangs for a January 1971 Motor Trend review, clocked the Boss at 5.8 seconds 0-60 mph, with a standing quarter-mile of 13.8 seconds at 104 mph. By contrast, a 429 Mach 1 took 6.5 seconds and did the quarter in 14.5 at 96.8 mph, though it might have been hampered a bit by its Cruise-O-Matic.

Car and Driver had lots of good things to say about the Boss 351 in a February 1971 road test. For starters, the "HO engine performs admirably…. It produces a generous quantity of power for its size and yet is remarkably tractable and docile." C/D explained this by waxing poetic about premium internal features like Boss 302-type "staggered valves the size of manhole covers and ports like laundry chutes. It makes the [Camaro's] Z-28 look like a gas-mileage motor.... [C]amshaft lobes lift the Boss' valves to rare heights for a street engine. In fact, only registered extremists like the L88 and aluminum-block ZL-1 Chevys have more valve lift than the Boss 351 engine." Topping it off was "a 750-cubic-feet-per-minute Autolite carburetor the size of an electric typewriter."

C/D judged the variable-ratio power steering as "not particularly quick on center" but "remarkably precise -- certainly as good as the best from Detroit -- and small steering corrections can be easily and accurately made."

Alas, hot-car demand was waning fast, and Ford fired this Boss at midseason after building only 1806.

But the editors had "serious doubts about the suspension. The car just doesn't handle well enough to be worth the punishing ride. It feels like all of the suspending was done by short lengths of oak two-by-fours…. [S]tylists should share part of the blame…. They demanded a low car, which means the engineers had very little room for suspension travel. Consequently, the spring rates had to be very stiff to avoid bottoming out. The Boss has what feels like cement springs, but it still bottoms readily--a situation that deals your hind end a healthy whack."

On the other hand, "it doesn't roll much and it will generate high cornering forces in situations where you can use plenty of power to keep the tail out. Without power it understeers fiercely.… [And if] the space available is really tight, [the driver] dare not apply power suddenly because the car will understeer even more. We prefer something with more nearly neutral-steer characteristics like the Firebird Trans-Am."

Critics had even more unkind things to say about the overall Mustang lineup. Read some of their comments on the next page.

For even more on the Ford Mustang, check out the following links.
  • Saddle up for the complete story of America's best-loved sporty car. How the Ford Mustang Works chronicles the legend from its inception in the early 1960s to today's all-new Mustang.
  • Mustang had it all for 1969 -- except buyers. Sales were lower still in 1970. In 1969-1970 Ford Mustang, you'll find out how a new president infused the brand with more performance.
  • With Lee Iacocca back in the saddle, Ford's ponycar revsited its roots. 1974-1978 Ford Mustang tells the story of the Mustang II with its smaller, lighter design and return to rationality.
  • The 1971 Ford Mustang Boss 351 was Ford's final high-performance Mustang of the classic muscle car era. Here's a profile, photos, and specifications.