1963 Chevrolet Impala SS: Fifty Aluminum-Nosed Z11s and a Racing Door About to Close

On August 21, 1962, Vince Piggins, head of Chevrolet's Economy, Safety and Performance department, sent a memo to eight colleagues, among them H. F. Barr, E. J. Premo and Zora Arkus-Duntov. As NHRA reproduces it, the memo called for two things. Ten Mark II 427-cubic-inch engines were to be prepared for Daytona Beach in February 1963. And 50 special 1963 Impala SS sport coupes were to be built with aluminum front-end sheet metal, hood, fenders, bumper and the rest, to carry Mark I 427s under a light-weight vehicle option coded RPO Z-11. Read today, it describes a Chevrolet planning to race harder in 1963, not less.¹

The two engines had different jobs. NHRA explains that when NASCAR confirmed it would allow 427-cubic-inch engines for 1963, both programs got a stroked crankshaft, 3.650 inches. The Mark I was the drag-strip engine, built from the existing W-series 409 and badged in Chevrolet's paperwork as the 430 hp Turbo-Fire 427. The Mark II, the 427 hp Turbo-Fire 427, was the engine meant for Daytona. The memo also records that Duntov would keep developing a hood that fed cold air to the carburetors. The Z11 was the drag-strip half of a two-engine program.¹

The package that reached the drag strip matched the plan. NHRA's history of the 409 lists the Z-11 as a $1,237 option and says the cars appeared at the 1963 Winternationals with aluminum front ends and 430 hp ratings. Chevy Hardcore's feature on a surviving car adds the details: dual Carter AFB four-barrels on an aluminum intake, 13.5:1 compression, cowl induction, and more than twenty weight-saving aluminum pieces including the hood, fenders and bumpers. Wikipedia's third-generation Impala article places the option on the Impala sport coupe. The 430 hp figure is an advertised SAE gross rating.^2,3,4

How many were built is not settled. The Piggins memo planned 50. Wikipedia says 50 Z11 cars were produced at the Flint plant. The Classic Industries chart lists 57, and Chevy Hardcore says many sources put production at 57, with fewer than 60 built. The memo's 50 is a plan, not a count; the chart says its figures have not been verified by the factory; and Wikipedia does not show the record behind its 50. Both figures stand until a Chevrolet build record settles the question. Either way, set against 153,271 Super Sports, the Z11 was roughly one car in every 2,700 to 3,100.^1,4,5,3

The ordinary Super Sport, meanwhile, was having its best year yet. The Classic Industries chart counts 153,271 Impala SSs for 1963, now under RPO Z03, against 99,311 in 1962. Measured against the chart's 832,600 Impalas, nearly one Impala in five was a Super Sport. Wikipedia describes the year's rectilinear styling with an engine-turned aluminum rear panel, and the Impala SS Registry lists the SS's own engine-turned exterior trim, SS badging and wheel covers, with 7.00 x 14 tires on the sport coupe and 7.50 x 14 on the convertible. V-8s dominated: the chart gives 735,900 V-8 Impalas against 96,700 sixes.^5,6,4

The street 409 was still the engine most buyers meant when they said 409. NHRA's history says it came in three versions for 1963, rated from 340 to 425 hp, all SAE gross. The chart counts 16,920 409 engines across the full-size line, up from 15,019. That row covers every full-size Chevrolet, not only Super Sports. Even if every one of those 409s had gone into a Super Sport, it would have been in no more than about 11 percent of the cars wearing the badge; by 1963 most SS buyers were choosing trim and comfort, not the big engine.^2,5

Then the door began to close. At 3:45 p.m. on January 24, 1963, a Pontiac bulletin told zone distributors that new orders for 389 and 421 Super Duty engines were cancelled that day. That bulletin is a Pontiac document, not a Chevrolet one, and it does not state the corporate reasoning. General Motors' broader position is on the record in chairman Frederic Donner's 1965 congressional testimony: the Automobile Manufacturers Association had adopted a June 1957 resolution against racing participation and speed advertising, and GM said it had made those provisions its own policy and continued to follow their spirit. Chevy Hardcore's feature says the ban effectively ended the Z11's competition career.^7,8,3

What the policy stopped, and what it left alone, is visible on Pontiac's side of the corporation. Over-Drive's 1963 Pontiac fact sheet lists three Super Duty 421 ratings, 390, 405 and 410 hp, marked available only until February 1, 1963, while the January bulletin kept the 421 HO on sale. For ordinary buyers Pontiac still catalogued the 421 in 353 hp four-barrel and 370 hp Tri-Power form. Chevrolet's catalogue kept its street 409s in the same way. The factory-built drag and stock-car specials ended; the big engines a buyer could order from a dealer stayed.^9,7,2

The cars that had been built went racing anyway, in private hands. Chevy Hardcore reports that Frank Sanders, the original owner of the car it profiles, won 19 of 20 races with it in 1963 and took a class title at the NHRA Winternationals; those claims come from the car's history and have not been checked against NHRA's own results. Pontiac's cars kept winning briefly too: on February 16, 1963, according to the Motorsports Hall of Fame of America, Paul Goldsmith won the American Challenge Cup in a Ray Nichels Super Duty Tempest. The Hall's display car is a recreation; the original, it reports, is believed to have been scrapped.^3,10

What followed shows how far the Super Sport had drifted from the drag strip. For 1964 the Classic Industries chart counts 185,325 Super Sports, now a series of their own, while 409 engines across the full-size line fell to 8,684, about half the 1963 figure. The 1963 Impala SS therefore sits at a crossing point. It was the biggest Super Sport year yet at 153,271 cars, and it carried the most extreme factory drag package Chevrolet had offered, a $1,237 option on 50 or 57 cars, planned in a memo in August 1962 and overtaken by corporate policy within months.^5,2,1,4