The History of the American Muscle Car Era - 1971

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1971 American Muscle Cars

1971

American Muscle Cars of 1971

Country:
USA
1971 Chevelle SS
The year of instantaneous decline is how many performance car fans perceived 1971. For, in one fell swoop, many of the hot machines were emasculated, with lowered compression ratios and the increased use of horse-power-robbing pollution devices, while some performance options were dropped altogether. And the insurance companies took full aim at the performance market by charging rates that were unaffordable for many. Though grim as it was, the party wasn't over quite yet. Change on all fronts continued to alter the country at a startling pace. People were fed up with the state of things and began to yearn for the past like never before. Nostalgia and relics of earlier days were suddenly in vogue, a trend that is still with us today.

It was General Motors that took the big step first, reducing compression ratios across the board for the 1971 model year. This was simply early preparation for the unleaded gas they knew would be necessary for use with catalytic converters. As it turned out, it was another four years before the converters came along, but that drop of two or three points in compression on all 1971 GM cars cost 20 to 30 hp right off the top. Casualties included the W31 Olds, Pontiac's Ram Air IV and the 375-horse .396, just to name a few.

Over at Buick, they had introduced their 455-cube Stage 1 option package the prior year. For 1971, they continued it unchanged with the exception of the drop in compression, but that slowed the car about a full second in the quarter, making its performance more like its 1969 400-cube equivalents. The LS6 engine in the Chevelle was a wilder combination than the Stage I Buick, with big-port heads, big 780-cfm Holley carb, solid-lifter cam and valve springs that permitted up to 6500 rpm if the driver was brave. But with only 9:1 compression, the old neck-snapping response wasn't there. Chevy engineers cut their gross power rating from 450 to 425. But factory documents showed the actual net power of the 1971 LS6 Chevelle to be about 325 hp at 5400 rpm. As a result, quarter miles were in the mid-14s at 95 to 97 mph with the 4000-pound weight.

The 1971 Camaro Z/28s still has a fighting chance with the low compression because of their modest weight. Their published net power was off to 275 hp at 5600 rpm. It should be mentioned that Chevrolet withdrew the 401-cube "Turbo Jet 396" L78 option from Camaros and Novas after compression dropped. Only the 454 LS6 and 350 LTl were retained as all-out performance options. Corvette was the only glimmer of hope at Chevrolet. A total of five engine options were listed—two small-blocks and three big-blocks—though the ZR2, ZR1, LS6 and LT1 were sold in limited quantities. The ZR2 was a $1747 option and was installed in just 12 Corvettes, making it highly collectible today. Like the LS7, which was never installed in production Corvettes, the LS6 454 featured aluminum heads, and just 188 were produced. These heads saved about 70 pounds. Of course, it was unlikely that a stoplight drag race would see such rare and expensive machines, but the ground would shake when these powerhouses were fired up.

1971 Pontiac Firebird
1971 Pontiac Firebird
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429 Cobra Jet V8
Pontiac's 455 HO was arguably the best engine from 1971. With only 8.4:1 compression ratio, it gave 300 net horses and 415 lb. ft. torque. Extrordinary.

1971 AMC Hornet SC/360
1971 AMC Hornet SC/360.

Chrysler decided to wait a year to cut compression. And since you could still get 100-plus octane fuel at the corner filling station, the hot Mopars got going while the going was good. For instance '71 was the last year for the famous Street Hemi, and Chrysler offered it in all its intermediate-sized cars with either 4-speed or automatic transmissions, and with the original high compression and a strong hydrautic camshaft.

The company put a net rating on it of 350 hp at 500 rpm, but that hardly told the story. Motor Trend strip tested a '71 Dodge with the Street Hemi and 4.10 gears. It turned a 13.73 ET at 104 mph. Admittedly, the insurance premiums on the Street Hemis were skyrocketing that year, and sales were falling off fast. But if you could afford to run one, you had just about a sure winner in the stoplight grand prix.

Chrysler officials also decided to keep their 440 Six-Pack engine option on the books for 1971, without major changes from '70. This combination had a net rating of 330 hp at 4700 rpm and was only a tick behind the Street Hemi in acceleration times, when in similar cars. You could figure on low 14s at 100 mph in a Plymouth Road Runner or Dodge Challenger. At an option price of under $500, it was one of the better performance bargains of the day. Especially as the 440 Wedge didn't attract high insurance premiums.

Even better off in the insurance scheme was Chrysler's excellent 340 small-block performance engine, netting 240 hp at 5000 rpm with a single crossflow muffler. This made a great combination in the light Darts and Barracudas of the day, but by the early' 70s, the intermediate Chrysler models had gotten too heavy for the small-block engine.

Ford, like Chrysler, waited until 1972 to drop compression ratios. This gave the Ford fans a leg up on the GM groupies. And since this was a year when the stagger-valve Cleveland and Lima V8s were being perfected, Ford fans has the machinery to play hardball. Unfortunately, the popular Mustang got the short end of the performance stick.

Not only were the wild Boss 302 and Boss 429 engine options dropped (they were no longer needed for Trans-Am and NASCAR racing eligibility), but it so happened that 1971 was the year when Ford upgraded the Mustang with another big dose of size, weight and luxury. Those all-new 1971s were 9 inches longer and 500 pounds heavier than the Mustangs of the mid-'60s. And this hurt performance.

Surprisingly, the 351 Cobra Jet could take a big-block 429. Both engines were similarly equipped, with big-port heads, 750-cfm Autolite carbs, hi-riser manifolds, hot cams and streamlined exhaust manifolds. The 351 was rated at 330 hp, while the 429 peaked at 370. And usually the small-block had a half second edge in the quarter mile. A super-rare option was the 375-horse 429 Super Cobra Jet, which had a stouter mechanical cam and rear axle ratios of either 4:11 or 4:56:1. The 429 Super Cobra Jet was also the top performance option for the Ford Torino, though the car was heavier. Admittedly, Ford never really did much with the engine, as it was just coming on when the muscle-cars were winding down.

Pontiac 455 HO



Olds and Pontiac hadn't completely given up. It was Pontiac that had carried the torch for so long with the GTO and hot street machinery of all kinds. Their big news for 1971 was essentially a scrambling of existing off-the-shelf parts that had been well-proven on previous Pontiac Ram Air engines. Despite the forced drop in compression in all GM cars, Pontiac's new 455 HO combination for 1971 GTOs and Firebirds proved to be one of their sweetest and most responsive street engines ever.

It was a worthy successor to the famous 400-cube Ram Air IV of 1969 to 1970. Pontiac engineers took the big-port heads, hi-rise aluminium manifold and split-flow exhaust manifold from the RAIV and combined them with the new 455-cube, four-bolt main block and the old 288-degree HO hydraulic cam from the '60s. The resulting combination had a beautifully flat torque curve over a broad rpm range, with quick, smooth response at all speeds.

Olds still had the excellent W30 option package for 4-4-2s, which featured one of the best street camshafts in the industry, plus one of the more efficient hood air scoop designs to get cool air to the engine for optimum breathing. Olds engineers put a conservative net rating of 300 hp at 4700 rpm on that 1971 W30 engine. But the torque was awesome, and throttle response seemed to lose little from the drop in compression.

But all told, it was a rough year for tradition. Even Rolls Royce went into receivership. And muscle-cars were fast becoming extinct. In motorsports, Richard Petty's Plymouth took the Daytona 500, and A1 Unser won Indy in a PJ Colt-powered by Ford. Jackie Stewart won his second World Championship, while Joe Leonard took the USAC title. It was a good year for racing.
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