While maintaining a basic resemblance to previous Mustangs, the 1971 Mustangs were the largest and heaviest yet. Every dimension increased including wheel base, to 109". Ford still built the Mustang in three configurations: hardtop, convertible and SportsRoof. On the SportsRoof, the rear window angle was only fourteen degrees from horizontal- this resulted in a cleaner aerodynamic look, but it was harder to see out.
The interior was redesigned as well. The dash used a three pod arrangement, and for the first time, power windows were optional. There were two interior options, the Decor Group and the Mach 1 Sports Interior, which was optional on any SportsRoof Mustang.
Base engine on all models was the 250 c.i. six cylinder, except the Mach 1 which came with the 210 hp 302 V-8. The 302 V-8 didn't provide much punch for a heavier Mustang. Optional V-8s were the 210 hp 302, 240 hp 351, 285 hp 351, 370 hp 429, 375 hp 429. All 351 V-8s were Clevelands. In May 1971, a low compression 280hp 351, called the 351CJ, replaced the 285 hp 351 V-8 that was available at the beginning of the model year. Both of these 351s had the same engine code, M.
The 428CJ was replaced by the 429CJ as the top Mustang engine. The 429 belonged to the Ford 385 Engine Series and as such, no parts were interchangeable with the older 428. Wider, larger, and heavier, the 429 would not readily fit into the 1970 Mustang engine compartment, which is one of the reasons why the 1971 Mustang got bigger. The cylinder block was a variation of the 429/460 block, of which the Boss 429 was also based on; the cylinder heads were similar to the 351 Cleveland in design. You could describe the 429 as a large Boss 302. As equipped in the Mustang, the 429CJ came with four-bolt mains, forged rods and pistons, 11.3:1 compression ratio, a hydraulic cam, (similar to the Boss 429's) very large ports and valves, and all 429CJs came with aluminum valve covers. The 429CJ came with a Rochester Quadrajet four-barrel carburetor, and some early units had adjustable valve trains.
The 429CJ became a 429SCJ if the Drag Pack option was ordered. It consisted of a 3.91 or 4.30 rear axle ratio with Traction Lock or a 4.11 ratio with a Detroit Locker rear. Both of these engines have the engine code C. Some Mustangs with the Drag Pack also included an external engine oil cooler, though of a different design than previously used. The SCJ engine came with a Holley 780 cfm carburetor rather than the Rochester Quadrajet, a mechanical lifter camshaft and adjustable rocker arms.
Although the 429s were available on any Mustang body style, the big engine was most often seen in the Mach 1, which was still the main Mustang performance model.
The Boss 302 and Boss 429 were no longer available , but in keeping with the Boss concept, there was the new Boss 351 for 1971.
1971 saw more of the performance options becoming available on regular Mustangs.
The Dual Ram Induction option, on 351 and larger engines, consisted of a
hood with two functional NASA type hood scoops, twist type hood locks, a
Tu-Tone paint treatment, and black or argent and Ram Air decals. It made any Mustang look better but really didn't do much as far performance goes.
Further watering down the overall performance image of the Mach 1 and Boss 351 Mustangs was the availability of the Sports Hardtop option late in the model year. Based on the hardtop body, it used he Mach 1s honeycomb grille and color keyed bumper, the standard Mach 1 hub cap/trim rings, the non-functional NASA hood and the Boss 351's side stripes.
1972
The 1972 Mustangs were externally similar to the '71s. You could tell them apart by the Mustang lettering on the rear deck lid. 1971 Mustangs had Mustang lettering that ran the full width of the deck lid. 1972 Mustangs got Mustang lettering, in script, only above the right taillight.
1972 stands out more for what you couldn't get anymore, namely horsepower. The 429 engines were dropped as was the Boss 351 and the remaining engines were all detuned to reduce emissions. This also meant reduced power. The base Mustang engine was the 98hp 250 c.i. inline six. The Mach 1 got the 302 c.i. V-8 rated at 140hp with two 351s, the two barrel rated at 177hp and the 351CJ rated at 266hp. Both 351s were of the Cleveland family.
There was the one last gasp at 1960s style high performance- the rare 351 HO engine option. This was basically a low compression version of the 1971 Boss 351 engine, rated at 275hp. About 1000 of these were made in all three Mustang body styles. Mandatory options with the 351 HO included the four-speed manual transmission. 3.91:1 rear axle ratio, the Competition Suspension, dual exhausts and the 15x7" chrome Magnum 500 wheels.
Well, if you couldn't go fast any more, you could at least look the part. All you had to do is order the Exterior Decor Group on the hardtop and convertible. It included the Mach 1 honeycomb grille and sportslamps, the color-keyed front bumper, hood and fender moldings, the lower bodyside paint treatment and the Mach 1 trim ring/hubcap combo. To round out the Mach 1 look, the Mach 1 tape side stripes could also be ordered.
Coinciding with similar Pinto and Maverick packages, was the Sprint package available on the Mustang SportsRoof and hardtops (fifty convertibles were also made). The Sprint combined the Exterior Decor Group with a special paint treatment. All Sprints were white with dual blue and red hood stripes, blue and red lower body treatment and a red rear taillight panel. A USA shield was located on the rear fenders while the white vinyl interior got white seats with blue Lambeth cloth. This was called the Sprint Package A. Sprint Package B was identical, but added the Competition Suspension with the chrome 15x7" Magnum 500 wheels with F60x15 tires.
