The 1971 Ford Mustang Mach 1 was not what it was in 1970 guise. First, base price went up a sizable $200 to $3268, and that bought only a standard 302-cubic-inch V-8, not a 351. Worse, retuning for this year's stricter emissions standards robbed the 302 of 10 horses, leaving it at 210 horsepower on unchanged 9.0:1 compression.
Yes, 351s were still available for the Mach 1 and other versions of the 1971 Ford Mustang: a 240-horsepower two-barrel ($45) and a 275-horsepower four-barrel ($93). With vehicle weights up so much, the base 200-cubic-inch six was sensibly scratched, leaving the torquier 250, though it, too, lost 10 horses, dwindling to 145.
At the top end of Mach 1 performance was again Mustang's big-block V-8. That engine was now a 429 -- which raised a few eyebrows -- but it wasn't the exotic semi-hemi of 1969-70. While this new Cobra Jet mill did have the same cylinder dimensions as the semi-hemi, it was essentially a short-stroke version of the Thunderbird/Lincoln 460-cubic-inch V-8, with wedge-type combustion chambers and conventional construction.
The 429 began the model year in regular (CJ) and ram-air (CJ-R) versions. Both had four-barrel carburetors, hydraulic lifters, and a nominal 370 horsepower, though most observers thought the cold-air ducting put the CJ-R at 380-385 horsepower. A solid-lifter Super Cobra Jet (SCJ) arrived a few weeks later at 375 horsepower, again with or without ram-air.
All 429s could be ordered with 3.91 and 4.11:1 rear axles, but the SCJ required those ratios and the optional Drag Pack with locking differential. None of these brutes was inexpensive at $372-$493, which likely explains why initial orders were so weak -- and why Ford decided to drop all three by midseason. Most probably went into Mach 1s, though they were technically available for any '71 Mustang.
According to Mustang chief program engineer Howard Freers, the 429 with its canted-valve heads "was a much wider engine than the 428, and that's why the car got wider" -- ironic in view of the engine's short tenure. "It took a [wider track] to get those monsters in there." But engineers took advantage of that to optimize handling for all models, which was "a major problem objective," Freers recalled. "I think we it…on the base model as well as the big-engine jobs." A key decision was fitting staggered rear shocks with any 351 or 429 engine.
The chassis wizards also recalibrated the base suspension to suit the bigger, heavier '71 package, revamped front-end geometry, and redesigned the steering gear. Cars with the comp suspension got variable-ratio power steering, allegedly borrowed from GM. Its chief advantage was needing fewer turns lock-to-lock, appreciated on fast, twisty roads.
A 429 Mach 1 was among the 1971 Mustangs that Chuck Koch tested for a January 1971 Motor Trend review. It did 6.5 seconds 0-60 mph, 13.8 at 104 in the quarter mile, topped out at nearly 114 mph and averaged just 9-10 mpg on premium gas.
By comparison, Motor Trend's test 1971 Mustang 302 hardtop posted 9.9 seconds 0-60 mph and 17.5 seconds at 78 mph in the quarter-mile. Top speed was 86 mph with the standard 2.79:1 axle. Fuel economy was 15.2-17.1 mpg on regular fuel.
The Boss 351 made most of the Mach 1 package standard -- and then added some options of its own. The next page tells you what this model had under the hood.
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.