1970 Chevrolet Chevelle RPO Z15 Super Sport 454 V8 Convertible

The intermediate-size Chevelle was introduced by Chevrolet in 1964. The public was impressed and sales were strong; in 1970, over 440,000 examples were sold. Chevrolet's ads for the Chevelle stated 'performance starts as soon as you're seated.'

The Chevelle in SS 454 guise was a very special vehicle, powered by the LS6 Turbo-Jet 454 V-8 option and produced an advertised 450 horsepower at 5,600 RPM and 500 foot-pounds of torque at 3,600 RPM, which were the highest performance numbers of the muscle car era. This was a factory option that could be purchased by anybody and cost just an extra $263.30 on the window sticker. In total, around 4,475 buyers made that choice and along with the high performance, also received higher insurance premiums. The car was capable of running quarter mile times in 13.44 seconds at a speed of 108 mph, utilizing 8.4 mpg of premium fuel.

The LS6 engines were assembled at Chevrolet's engine production facility in Tonawanda, New York. Workers began with a four-bolt block that featured pre-tapped holes for a track-ready external oiling setup. The block housed an alloy steel crankshaft that was cross-drilled to maximize oiling capabilities. Tied to the crank by 7/16-inch rod bolts were eight forged steel connecting rods (magnafluxed for added rigidity). Eight TRW forged aluminum pistons squeezed the fuel/air mixture to an 11.25:1 compression ratio. Heavy-duty 3/8-inch pushrods transferred cam timing to the valves through 16 sets of beefy dual valve springs. The engines were given a Holley four-barrel carburetor on an aluminum dual-plane intake. Deep-groove pulleys and a modified distributor were fitted, and a large air cleaner to take air from the RPO Code ZL2 cowl induction hood was also included. With the engine, mandatory options included the M22 Muncie four-speed transmission and a heavy-duty battery.

In 1970, Chevrolet produced 53,599 examples of the Chevelle Super Sport (SS). Of those, just 8,773 were SS 44s and just 4,475 included the LS6 option, with the majority built as two-door coupes. The exact production figure for 1970 LS6 Convertibles is not known, but is estimated to range from 20 to 80.

This LS6 Chevelle Convertible was previously part of the Milton Robson collection. He acquired the car in March of 1991 from another well-known muscle car collector, Carl Dwiggins, who restored the Chevelle from the ground-up.

The current owner acquired the car in November of 2010 and has properly stored this 50,000-mile car. It is painted a Medium Turquoise Metallic (Code 34), with a white convertible top and parchment interior that features optional Strato-bucket seats. It rides on the appropriate white letter Goodyear Polyglas tires ride on Magnum 500 wheels, and the car is fitted with an AM radio, a clock, and full instrumentation. The car has an additional two unique features which include the stripe delete and the cowl-induction delete.

By Daniel Vaughan | Jan 2015