In the 1970s Chevy hired British engineering firm Cosworth to design a high-performance version of the modest Vega—and succeeded
When Chevrolet's new compact, the Vega, came to the market for 1971, it was intended to compete with imports landing on both U.S. coasts.
Shortly before the car's introduction, then Chevrolet General Manager John Z. DeLorean directed his staff to develop a high-performance "halo car" variant.
One of the leads he suggested was Keith Duckworth of England's Cosworth Engineering, to see if they could develop a hot version of the Vega's newly developed aluminum four-cylinder motor. John Z thought the motor would form a good basis for a full race version, and in 1970, both Chevrolet and Cosworth started development work.
THE VEGA LAID AN EGG
Meanwhile, the production Vega was turned loose on the marketplace and laid an egg. Economy cars weren't trendy, let alone one with an all-aluminum engine (GM should've figured that one out from the Corvair).
On top of that, the "sporty" Vega GT was tanking, since it was nothing more than trim and decals, and those didn't count for much when sitting next to a Chevelle SS 454 on the dealer's lot. Good news was needed for the Vega line, so upper management put the heat on their engineering department and Cosworth to come up with a wonder motor.
However, at Cosworth, they were discovering what millions of Vega owners would eventually find out: the all-aluminum block was prone to failure. Developed by GM engineers with the assistance of Reynolds Aluminum, it was the world's first (and so far only) all-aluminum block, including the cylinder bores.
In lieu of steel sleeves, the block was cast from a high-silicon-content alloy, which initially seemed to wear at the same rate as steel. In reality, most engines started to wear out of tolerance within 40,000 to 50,000 miles. What Cosworth was also finding was that while they could develop gobs of power with their twin-overhead cam cylinder head (up to 290 hp at 9, 000 rpm); the blocks would break, especially at the bottom. Discouraged, and lacking the capacity for volume production, Cosworth licensed the head design to Chevrolet for further development.
Despite this news, GM gave the Vega TC (its code-name internally) the green light. Sales were still sluggish, and the "race on Sunday, sell on Monday" mantra was deemed the Vega's best hope. In this case, racing was SCCA Production B sedan class, Chevy's target from nearly day one, due to what was happening both here and in European 2-liter class sports car racing.
Based upon computer models, the Vega TC was expected to be competitive, if not have a slight edge (being in a lighter body) than both the BMW 2002 and the Alfa Romeo GTA. Chevy's plan was to have at least 1,000 examples of the hot motor available in the Vega to homologate it for the series. Several forms of induction were considered. The best setup, with Weber sidedraft carburetors, was not in the cards, as the DCOEs could not be smogged (as BMW found out with the 1600ti, thusly creating the famous 2002).
The only carbureted variant considered for production used the Weber-designed, Holley-built DGAV-type progressive downdraft two-barrel. Fuel injection appeared the best bet, but GM's Rochester Products division was only interested in developing a complete integrated system (to include a sealed fuel system and catalytic converters).
Externally, systems from both Lucas and Bendix were considered, with the latter getting the nod for production. The engineers continued to improve the durability of the engine blocks, and the whole twin-cam program was targeted for the 1974 model year. Press releases, sales material, color and trim selections, and even a test by Car & Driver magazine were slated.
MOTORS DETUNED FURTHER
Increased emission regulations meant the motor needed to be detuned further. This was no easy task, as the package was originally designed for a 12:1 compression ratio and struggled at 8.5:1 and 110 hp--a far cry from 290. But what caused the missed production date was that the motor failed its EPA certification test, due to burned valves from an overly lean fuel mixture and advanced timing.
During the year, one of several changes made was the color combination. Originally intended to be a silver car with black trim, John DeLorean changed his mind and production cars were black with gold trim. From the first car out of the Lordstown, Ohio, plant until the last scheduled 1975 model, all Cosworth Vegas were black and gold. Black was unavailable on any other Vega that year.
The Cosworth package made the Vega the second most expensive car in the Chevy line, at $5,916. This was nearly twice the price of a standard Vega, a fact that Chevy's ad agency used in several ads for the car when it finally hit the street.
What a Cosworth buyer got for the money was more than just a fancy cylinder head with electronic fuel injection on a stock aluminum engine block in a black and gold package. The car also featured a four-speed manual transmission, firmer springs, sway bars front and rear, unique alloy wheels shod with radial tires, full instrumentation with a gold-toned, engine-turned dashboard, and a dash plaque with a series number on it.
NOT JUST BLACK IN '76
For 1976, the overall Vega line saw a couple of cosmetic changes, mostly characterized by the parking/turn signal lamps hiding behind a three-slat grille (like an early Fedders air conditioner) that extended entirely between the headlights, plus larger taillights.
These changes spilled over to the Cosworths, which were now offered in seven additional paint colors (Antique White, Dark Blue Metallic, Firethorn Metallic, Mahogany Metallic, Dark Green Metallic, Buckskin, Medium Orange, and Medium Saddle Metallic) with additional interior color and material combinations. Also, the brakes were improved slightly and a 5-speed manual transmission was made optional.
The $6,000 price tag and less than spectacular power output guaranteed that Chevy was not going to exceed the forecast limited production of 5,000 units. In fact, 2,061 cars built in 1975 and another 1,447 the following year meant there were some left-over engines. Most sources estimate that 5,000 engines were hand-assembled. While a few engines were used for warranty replacement, none were actively marketed for off-highway performance, so they stayed in inventory until the early 1980s, when around 500 were disassembled for parts and the remainder scrapped for a tax write-off.
For the final year of the Vega in 1977, the Cosworth was gone, but one could get close with a Pontiac "Iron Duke" steel-block four-banger, the five-speed tranny, the Cosworth's F41 suspension package, and it even came in black.
Today, it is not at all difficult to find a well-cared-for, low-mileage Cos-Veg, as they were something of an "instant collectible" in their day. They also attracted an immediate cult following of an ardent (albeit small in number) cadre of enthusiasts. The best example to buy would be from one of these club members.
As good quality examples are still generally available (including the occasional minimal mileage new examples at a dealer), don't buy a restoration project. The hopeless rust-out issues and problematic engine block owned by someone who didn't religiously maintain it make the restoration of any Vega just silly. The unique twin-cam pieces are just icing on the cake.
ONE FOR THE PRICE OF TEN
Rough cars are best used as powertrain donors for others. Although the Bendix fuel injection was a compromise, and tuned so closely that all components were numbered as a set, it is generally best to leave it as stock. However, if you enjoy turning up your nose at 1975 EPA regulations and don't live in California, ditch an uncooperative setup and go with a pair of Weber DCOEs, as Cosworth had intended.
Examples in worthwhile condition have generally stayed within $2,000 of their original MSRP for over the last decade. However, better examples are starting to get noticed and there have been some slight market adjustments upward. The Cosworth-Vega might have been a Vega for the price of two when it was new--now it's about the price of ten.
Years Produced: 1975-76
Number Produced: 3,508
SCM Valuation: $5,000-$7,500 (at time of print)
Tune-up Cost: $400
Distributor Caps: $10
Chassis # Location: Driver's side of the dashboard, driver's side cowl near the plenum chamber, the engine bell housing flange adjacent to starter
Engine # Location: Engine bell housing flange adjacent to starter
Club Info: Cosworth Vega Owner's Association (COVA), P.O. Box 5864 Pittsburgh, PA 15209
Web Site: http://www.cosworthvega.com
Alternatives: 1974–76 BMW 2002tii, Alfa Romeo GTV, 1970–77 Mercury Capri
Investment Grade: C-