History of the Chevelle SS 1964-1972

Chevelle SS
The Chevelle SS represented Chevrolet's entry into the muscle car battle. Early 1964 and 1965 Chevelles had a Malibu SS badge on the rear quarter panel (part of the Z16 option priced at US$1,501 in 1965,[1] had the emblem on the front fender, as well as distinct in-house style numbers, 737 for the hardtop, 767 for the convertible;[2] 201 Malibu SS396s were produced); after 1965, the Malibu SS badging disappeared except for those sold in Canada. The Chevelle SS, which became a regular series of its own in 1966 called the SS396 (style numbers 817 and 867 that year),[3] was the high performance version and had its own line of engines and performance equipment. The performance engines available included 396 CID V8s – rated at 325 hp (242 kW), 350 hp (260 kW), and 375 hp (280 kW) respectively (the mid horsepower 396 was rated at 360 hp (270 kW) for 1966 only and 350 hp (260 kW) thereafter). The SS396 series only lasted three years from 1966 through 1968 before being relegated to an option package, just like air conditioning or a radio. The 1966 and 1967 model years also saw the limited run of the 'strut back' two-door sport coupe with its own syle number, 17.[3]

Two prototype Z16 Chevelles were built at the Baltimore plant and all regular production Z16 Chevelles were built at the Kansas City plant. Whether these two prototypes and the one reported convertible are included in this 201 figure isn't known. The one convertible was reportedly special built for Chevy General Manager Semon "Bunkie" Knudsen but is commonly called the 201st Z16 Chevelle and is commonly understood to have been destroyed. The original Z16 convertible supposedly surfaced in Art Astor's famous auto collection; it has been proven to be a fake.

The Z16 option included a convertible boxed frame, a narrowed rear axle and brake assemblies from the contemporary Impala, heavy-duty suspension, plus virtually all Chevelle comfort and convenience options. The Z16 standard big-block 396 Turbo-Jet V8 came only with the Muncie wide-ratio four-speed manual transmission. The rear of the Z16 had a unique black and chrome trim panel which framed untrimmed Chevelle 300-style taillights (Malibu and Malibu SS models had bright metal trim attached to the lenses).

1966 saw a complete restyle of the Chevelle on the old frame. The new body reflected the "Coke bottle" body shape that became the fad for American cars in the mid-1960s. Bulging rear fender lines and a "flying buttress" roofline (where the rear window was recessed into the "C" pillar) were highlights of the '66 hardtops, shared with other GM "A" body models. The SS396 became a separate model, and the only Super Sport available. It was produced as a regular production model, and quite a few were sold. 1967 saw a slight restyle of the '66 body, but an entire host of new safety equipment became standard that year,[citation needed] making the '67 a much safer car to be in the event of a collision. The SS396 continued as the only Super Sport model, in both Sport Coupe and Convertible body styles.

For 1968, a new body style (though still under the 817 and 817 internal designations)[4] emphasized the "Coke bottle" look even more, and a semi-fastback roofline for hardtop coupes became extremely popular. New Federal safety-mandated equipment included side marker lights on each fender, as well as shoulder belts for outboard front seat occupants on cars built after December 1, 1967. This explains why some '68s had shoulder belts, and some early-production cars did not. All '68s had anchors for the belts, however. Manaul transmission cars got GM's "Air Injection Reactor (A.I.R)" smog pump, which added complexity under the hood.

For the 1969 model year, the SS396 series was dropped and the Super Sport became a performance option. In 1969 the SS option could be ordered on the 300 Deluxe 2-door Sport Coupe (style number 13337)[5] and 2-door sedan (13327)[5] as well as the Malibu 2-door Sport Coupe (13537)[5] and convertible (13567),[5] as well as the El Camino (13580). All '69 Chevelles also got a new locking steering column, one year ahead of the Federal requirement. Headrests, required for all cars sold in the U.S. after January 1, 1969, were installed on all '69 GM cars, but on cars sold before the law went to effect had the option of deleting them. In 1970 the SS option was limited to the Malibu series (2-door Sport Coupe, convertible, and El Camino). In both 1969 and 1970 the SS option included the 396/402 as the base engine keeping the option alive as a performance-oriented choice. This changed in 1971 when the SS option could be ordered with any optional V8 and became more of a dress-up option than a performance option.

Prior to 1970, GM had a restriction stating no mid-size car could have an engine with a displacement over 400 cu in (6.6 L). Don Yenko, a Chevy dealer outside Pittsburgh, Pennsylvania, discovered a way to get around that edict. Don used the Central Office Production Order system, which normally filled special-equipment fleet orders, to create a special COPO that included the L72 427 cubic inch 425 425 hp (317 kW) engine and the needed drive train upgrades. A few other dealers ordered the package Yenko created and sold them as their own supercars. (Berger, Sunico, etc)

In 1970, GM dropped the displacement rule, and bigger engines became available as regular production options, resulting in the addition of an SS454 option to the existing SS396. The 454 cu in (7.4 L) LS5 V8 was rated at 360 hp (270 kW) (390 hp (290 kW) in Corvettes) and the LS6 at 450 hp (340 kW). The LS6, with 450 hp (340 kW) and 500 ft·lbf (680 N·m) of torque, would provide 1⁄4 mi (400 m) strip performances in the low to mid-13 second range at 105–108 mph (169–174 km/h). In fact, the stock 450 hp (340 kW) LS6 tied the 1966 Corvette early production 427/450 hp as the highest horsepower engines offered by any manufacturer during the muscle car era. There were more powerful engines offered by GM during those years but they were underrated to keep the less savvy buyers from ordering them for street use. The ZL1 and L88 427s both were rated at 430 hp (320 kW), but actually produced well over 500 hp (373 kW) in stock configurations. They were "race only" engines and very very few were ever installed in production cars. Most were ordered by racers who had factory connections or sold over the counter parts.

For 1971, GM mandated all divisions design their engines to run on lower-octane regular, low-lead or unleaded gasoline due to tightening emission requirements and in anticipation of the catalytic converter that would be used on 1975 and later models, necessitating the use of unleaded fuel. To permit usage of the lower-octane fuels, all engines featured low compression ratios (9:1 and lower; well below the 10.25-11.25:1 range on high-performance engines of 1970 and earlier). This move reduced horsepower ratings on the big-block engines to 300 for the 402 cubic-inch V8 but surprisingly, the LS-5 454 option got an "advertised" five-horsepower increase to 365. The LS-6 454 option, which was originally announced as a regular production option on the Chevelle SS for 1971, was dropped early in the model year and no official records indicate that any 1971 Chevelles were assembled with the LS-6 engine.

In the face of declining musclecar sales following the "insurance surcharge" wrath of 1970, the Chevelle SS – at least in base form – changed from a specific performance car to a trim package, much like the original Chevelle SS models that pre-dated the introduction of the SS396 in 1966. For 1971, the base Chevelle SS engine was a two-barrel 350-cubic-inch V8 rated at 245 gross (165 net) horsepower and optionally available was a four-barrel carbureted version of the 350 V8 rated at 275 gross (200 net) horsepower. The big block engines of previous years were now extra-cost options including the 402 V8 rated at 300 gross (270 net) horsepower; and LS-5 454 V8 with 365 gross and 285 net horsepower. Chevrolet specifications for 1971 included both "gross" and "net" horsepower figures for all engines to ease the transition to 1972 and later years, when Chevy and other manufacturers only listed the "net" horsepower ratings.

The 1972 Chevelle SS had a top engine rated at 270 net hp (201 kW) conforming with GM's decree that all engines were to be rated at their net engine ratings. Despite the lower rating there was no evidence that power had actually changed on production cars of that year. All other engines on the SS roster were unchanged from 1971.

In mid-1971 and continued through 1972, the base Chevelle Sport Coupe was offered as the "Heavy Chevy" model featuring special striping and other appearance items. The "Heavy Chevy" was available with any V8 engine offered in the Chevelle roster ranging from the 307 two-barrel to the 402 four-barrel. However, the 454 big-block was only offered with the "SS" package and not available with the "Heavy Chevy" option.

The Yenko Chevelles
Retired race car driver Don Yenko, (at the time making a living as a Chevrolet dealer), developed his own line of signature Chevelles, along with his own models of Camaros and Novas, which became the Yenko Super Cars. At the time, the largest engine being installed in Chevelle SS's was the 396 cid V8. Yenko decided to equip his acquired models with the Chevrolet 427 cid V8. While being an extremely limited edition of Chevelles, they nonetheless proved very popular among Chevy lovers across the country. Today at auction, the Yenko Super Cars can bring as much as $2.2 million.