Impala SS (61 – 96)
1961 saw the introduction of the first real muscle car, the Chevrolet Impala SS. This year also saw the introduction of Chevrolet’s 409 cubic inch V8, the engine that catapulted the Big Three automakers into a horsepower war that would endure far into the 1970s. The 409 was really developed in response to Ford’s new 390 CID engine, which outperformed Chevy on the drag strip. Although it produced “only” 360 horsepower, compared to Ford’s peak 375 bhp, the additional 19 cid earned it street respect and immortality (“She’s very fine, my 409”).
Chevrolet debuted the Super Sport (SS) option package, which was available as an option on the 348 and standard on the 409 and would characterize Chevrolet performance for the next several years. At $53.80, the Super Sport package included unique body and interior trim, power steering, power brakes with sintered metallic linings, full wheel covers with a three-blade spinner, a passenger grab bar, a console for the floor shift, and a steering column-mounted tachometer. The 409 engine was available exclusively with a four-speed manual transmission and a single factory axle ratio. Lower axle ratios were available through the dealer, and owners were able to achieve 1/4-mile times in the upper 15s, which was quite amazing in 1961. Unfortunately, the 409 came equipped with 11.25 compression and a four-barrel carburetor, and because of the wedge-shaped combustion chambers, additional performance improvement was difficult. However, this is irrelevant. Although only 142 Impala SS 409s were constructed in 1961 (the majority of which were sold to loyal customers who would race them at local drag strips), the legend was established, and the horsepower race began.
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Chevrolet increased production of the 409 and made it available in all full-size Chevrolets, including the Biscayne, Bel Air, and Impala. This year’s Impalas were slightly less aerodynamic, prompting several competitors to opt for the lighter, slicker Bel Air coupe. The 409 was enhanced by installing new cylinder heads and modifying the camshaft. The 409 developed 380 horsepower when equipped with the standard four-barrel carburetor. However, the big news was the revised top-of-the-line 409, which gained a pair of Carter AFB four-barrel carburetors and a lighter valve train, producing an astounding 409 horsepower, or a remarkable 1 bhp per/cid. The 409 legends increased in stature.
The Impala SS continued to improve in performance and appeal in 1963. After the Bel Air coupe was discontinued, consumers returned to Impala SS coupes and convertibles. The 409’s drive ability was further enhanced, and a detuned version with 340 horsepower was added as an option with a Powerglide automatic transmission. Chevrolet produced a 409 with solid lifters and a single four-barrel carb capable of 400 bhp, as well as a 409 with two four-barrel carbs capable of a whopping 425 horsepower. As if that weren’t enough, Chevrolet debuted a new engine in mid-1963, the Z-11. This was a 427 cubic inch V8 engine that was built roughly on the existing 409 but had a smaller bore and a longer stroke. It was dubbed the “porcupine head motor” because to its tilted valves. Although it was officially rated at 430 horsepower, it easily exceeded 500 horsepower and was an instant hit on the drag strip. Regrettably, it was only available to factory-approved Chevrolet customers via the RPO (Regular Production Option). It was frequently paired with the factory-installed lightweight front end – aluminum panels and bumper – as an option. Additionally, Chevrolet was developing a new 427 V8, dubbed the Daytona “Mystery Motor,” for use in the 1963 Daytona 500. Chevrolet, on the other hand, withdrew officially from racing competition, effectively ending development of the “Mystery Motor” and after only 55 Z-11 Impalas were constructed. The 427 would not emerge for another three years, but it would be a direct descendant of Chevrolet’s 1963 “Mystery Motor.”
The Impala SS became its own series in 1964 and retained its distinctive external ornamentation and opulent interior. The SS was only available as a convertible or Sport Coupe and featured the same engines as the 1963 model, including the top-of-the-line 409. However, the Pontiac GTO would steal the Impala SS’s thunder as purchasers began to gravitate toward smaller, lighter automobiles that offered comparable performance at a lower price point than the full-size car.
In 1965, the Impala was totally redesigned, adopting a more streamlined appearance rather than the boxy appearance of previous years. The formidable 409 was phased out in February and replaced with the Mark IV 396 CID V8, which would power Chevrolets for the remainder of the 1960s. The new 396 may be paired with a new automatic transmission called the Turbo Hydra-Matic 350. The 396 was descended directly from the “Daytona Mystery Engine.” The 409 and 396 engines were offered in all Impala models, including four-door sedans and station wagons, although the Impala SS remained a separate series. 1965 also saw the introduction of the Impala’s Caprice option, which came standard with a V8 engine.
Chevrolet discontinued the SS option on all full-size cars saves the Impala SS 427 due to weak sales. The 1969 Impala SS introduced redesigned pontoon-bulge fender lines and a “full door glass” design that omitted vent windows. The 427 engines from the previous year was retained. Only 2,455 Impala SS 427s were sold, ensuring that this would be the final year for the legendary Impala SS. The Impala line would continue, with the new 454 cubic inch V8 engine debuting in 1970 and lasting until the late 1970s. However, the Impala never regained its performance reputation and evolved into a premium full-size sedan. However, in retrospect, an amazing 918,000 Impala SS were produced, demonstrating the car’s significance.
Impala SS sales continued to decline as purchasers shifted away from full-size performance. The SS came to resemble the normal Impala more and more, with the exception of a black-accented lower body sill and brilliant fender moldings. The engine options were reduced to a 396 with 325 horsepower or a 427 with 385 horsepower. Additionally, the Impala introduced a slew of new safety and convenience features, including a dual master cylinder brake system, an energy-absorbing steering column, and an ignition switch lighted by the first application of fiber optics technology in a Chevrolet.
The Impala SS reverted to an option for 1968, with only 38,210 of 710,900 Impalas purchased. The SS option was now offered on three models: convertibles, sport coupes, and custom coupes. Despite persistent declines in sales, both the 396 and 427 engines were retained.
Chevrolet discontinued the SS option on all full-size cars saves the Impala SS 427 due to weak sales. The 1969 Impala SS introduced redesigned pontoon-bulge fender lines and a “full door glass” design that omitted vent windows. The 427 engine from the previous year was retained. Only 2,455 Impala SS 427s were sold, ensuring that this would be the final year for the legendary Impala SS. The Impala line would continue, with the new 454 cubic inch V8 engine debuting in 1970 and lasting until the late 1970s. However, the Impala never regained its performance reputation and evolved into a premium full-size sedan. However, in retrospect, an amazing 918,000 Impala SS’s were produced, demonstrating the car’s significance.
Chevrolet brought back the Impala SS in 1994, 25 years after the last one went off the assembly lines in 1969, to add some flair to the full-size Caprice. The Impala SS was genuinely a modern muscle vehicle, equipped with a high-performance V8 and rear-wheel drive and covered in bodywork that matched its performance aspirations. Though it was only available for three model years, it quickly became a cult classic and a fitting tribute to the 1960s’ legendary Impalas.
The Impala SS made its début in 1994 as a high-performance vehicle based on the Caprice full-size chassis. Although it was the first four-door sedan to bear the renowned “Impala SS” moniker, Chevrolet made certain it lived up to its pedigree.
As such, it featured rear-wheel drive and commanded attention on the road. The Impala SS was available only in black and featured a body-colored grille, body-colored front, and rear fascias, rocker moldings, door handles and key locks, taillamp moldings, raised Impala SS logos along with the rear fenders, a unique rear deck-lid spoiler, and Impala emblems on the sail panels and rear deck lid. Gray leather upholstery with highly curved front bucket seats and a black satin finish on the instrument panel and door trim panels comprised the interior. However, the engine is the heart of a muscle automobile, and Chevrolet did not disappoint. The Caprice’s 180 horsepower V8 was replaced by a new 5.7-liter LT1 V8 with Sequential Fuel Injection derived from the Corvette, tuned to provide 260 bhp at 5,000 rpm and 330 lb.-ft. of torque at 2,400 rpm. The engine was mated to a standard GM electronically controlled 4L60-E four-speed automatic transmission with a final drive ratio of 3.08:1 and a restricted slip differential. Additionally, Chevrolet equipped the Caprices with a specific ride and handling suspension developed from the Chevrolet law enforcement package, as well as a quick-ratio power steering unit (12.7:1 vs. the standard 15.3:1 ratio). Stabilizer bars tuned front and rear and de Carbon gas-pressure shocks helped the Impala maintain its composure in the twisties, while big 17′′ x 8.5′′ five-spoke cast-alloy wheels wrapped in massive P255/50ZR17 tires kept the Impala SS linked to the road. Standard four-wheel ventilated disc brakes with a 12′′ diameter and a four-wheel anti-lock braking system brought the car to a halt in the event of an accident.
1995 saw just minimal changes. Whereas the preceding year’s window had a little plastic insert slightly forward of the C-pillar, this curvature was stamped into the body panels in 1995. Impalas are now available in two new metallic colors: Dark Cherry (a dark purple) and Dark Green-Gray Metallic. Additionally, the mirrors were moved from the door to the window frame and could now fold away.
1996, the Impala SS’s final year, changes were minimal. The shifter had been relocated to the console, and the dash now included an analog instrument cluster. The fuel pressure and voltage gauges have been removed in favor of a tachometer and analog speedometer. Although production of the Impala SS ended on December 13, 1996 (far into the 1997 model year), all Impala SS vehicles made were designated as 1996 models.
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