A bead of sweat trickled from under my helmet as I eased up to the starting line, the race-bred four-valve dual-overhead cam engine rasping through stainless steel headers at a steady 1,200 RPM. Narrowing my steely blue eyes, I blipped the throttle – resulting in a huge burp as a slug of gas from dual Weber 42 DCOE carbs loaded up the engine! Raw gas dribbled out the twin-tipped exhaust as I once again debated the wisdom of subjecting a 43 year-old car and its senior discount-eligible driver to the rigors of the track. With authoritative purpose, the starter pointed to me; “You’re up.” My lips curved into a grin and, throwing caution to the wind, I wound it up a few thou, dumped the clutch and – well, maybe I need to back up a bit first…
Author’s Note: After much teasing from Chevrolet Public Relations, Vega launched on September 10, 1970 – exactly 50 years ago today. I had planned a piece on its Golden Jubilee, but this oft-delayed and lengthy account of my Cosworth Vega and its history simply ate up too much time. It will have to suffice as my hat tip to a significant milestone for what should have been a much-more-significant automobile.
You see, my first car was a base 1971 Vega 4-speed notchback purchased used by my Dad in 1972 – he had to rebuild the engine at about 40K miles, and I remember grinding the valves under his supervision in his tiny garage workshop. It got passed on to me in 1979 for my last year of High School, at which point it had clocked around 80K miles and was again consuming a gallon of 10W-30 every other week (“Check the gas and fill up the oil”). I bought spark plug anti-foul adapters by the gross! Christmas Holiday was spent swapping in a freshly-rebuilt sleeved GT engine wearing an aftermarket header and Cherry Bomb shorty; it sounded far faster than it was, but proved to be reliable and returned nearly 30 MPG on the highway. I repowered the car with a Buick 3.8l V6 and THM350 over the summer of 1985, and would own it a total of eight years, with over 220K showing on the odometer when I used it as a trade on a new 1986 Suzuki Samurai. Being my first car, it played a significant role in my formative years and force-marched me through a Masters-level auto mechanics course in those early years of ownership. It will always be my favorite…
Chevrolet’s Vega was of course winner of Motor Trend’s 1971 Car of the Year Award, but corporate and labor infighting, plus substantial quality issues that quickly reared their head, earned it a blistering chapter in On a Clear Day You Can See General Motors, a “Deadly Sin” award on these pages, and a reputation that far outlived Vega’s numerous early problems. Anecdotes of blown head gaskets and furious rusting aside, the car’s worst issues had been mostly rectified by the mid-1970s (by mid-1970s expectations, mind you); the H-body platform would itself soldier on for ten years with over 3.5 million units produced (~2MM of which were Vega/Astres), evidence it perhaps wasn’t quite the abject failure the Interwebs make it out to be. One thing’s for sure, however: GM will never resurrect the Vega nameplate.
But to understand the genesis of the Cosworth Vega, we need to roll the clock back quite a bit farther – all the way to 1956, in fact, when John DeLorean joined General Motors’ Pontiac Division, reporting to Chief Engineer Pete Estes who was under recently-appointed Division Head, Bunkie Knudsen. DeLorean was a key player in the rapid turnaround of Pontiac, with input on the 1959 ‘wide tracks’ as well as the innovative 1961–63 Tempest.
Seeking to borrow from the performance cachet of high-revving European OHC racing engines, he oversaw the creation and introduction of the Pontiac Overhead Cam Six (OHC-6) engine. The OHC-6 was offered in a state of (de)tune that ensured reliability on American highways, but also utilized advanced features such as a deep-skirt engine block design (bottom edge of the block extends well below the crankshaft centerline for stiffness), aluminum cam-carrier and a fiberglass-reinforced, neoprene-impregnated nylon fabric belt – three features that would be reprised in the Cosworth Vega engine.
The OHC-6 would not enter production until 1966, and in the meantime, DeLorean continued repositioning Pontiac as GM’s ‘performance’ division. Despite a ban on factory-sponsored racing and a corporate policy limiting the upcoming A-body’s engine size, the 1964 Pontiac Le Mans debuted with a “GTO” option package powered by a 389 c.i.d. (6.4 L) V8 engine rated at 325 or 348 HP in ‘Tri-Power’ form. Bucking initial sales forecasts, over 32,000 GTOs sold the first year, kicking off “The Great Muscle Car Epoch.”
The following year, Ed Cole would direct DeLorean – now head of Pontiac Division – to create a Pontiac version of the recently-introduced Camaro. Re-running his successful ‘drop in a bigger engine’ play, the Firebird would initially be offered with everything from an OHC 6 up to a 400 c.i.d. (6.6 L) V8, “detuned” (with an easily-removed tab on the carburetor) to 325 gross hp.
DeLorean would tap into the “no replacement for displacement” play for his last time at Pontiac with the 1969 Grand Prix. Essentially a ‘long nosed GTO,’ it was available with up to 390 HP in SJ H.O. trim, and first year sales of the car jumped by almost 400%.
Elsewhere in GM, work had been ongoing to develop a ‘small car’ successor to the Corvair to compete with the VW Beetle (as a point of reference, US sales of the Beetle peaked in 1968 with 399,674 units sold). A number of conceptual directions were explored, some that utilized radical powertrains such as a rear-mounted radial engine. The ‘prime path’ was nailed down in 1967 when what would become Project XP-887 – developed by GM corporate engineering and design staffs – was selected for production over proposals originating from within Chevrolet (the XP-813 shown above) and Pontiac Divisions. The Vega would be the first GM vehicle developed with one person in charge, Development Engineer James (Jim) Musser, Jr., who managed a team of around 50. It is of interest to our story that, during an early review of Project XP-887, Ed Cole requested that, in addition to a full line of body styles including a two-passenger coupe, the car have provisions for a V8 engine option.
In October, 1968, GM Chairman James Roche announced that GM would introduce a new small car in the US within two years. Early the next year, DeLorean was tapped as General Manager of faltering Chevrolet Division, with marching orders to “turn the division around.” Project XP-887 was at this point still in early stages of planning and development, and DeLorean later recounted that, “[The Vega] produced a hostile relationship between the corporate staffs, which essentially designed and engineered the car, and Chevrolet Division, which was to sell it… General Motors was basing its image and reputation on the car, and there was practically no interest in it in the division. We were to start building the car in about a year and nobody wanted anything to do with it.” Yet, even as DeLorean set about getting the program on track, he was already thinking about how to create yet another successful halo car based on the Vega. But instead of throwing cubic inches under the hood, he would use something more along the lines of the OHC-6 approach.
Now it’s fairly well-documented in Vega canon that Chevrolet Division had been working on its own new 4-cylinder engine design, utilizing a cast-iron block and aluminum cross-flow OHC head; it’s even mentioned in this December 1968 blurb in Popular Science. But upcoming emissions requirements (the Clean Air Act of 1970) were proving to be a stumbling block for that engine. Ed Cole instead decided to pursue a new silicone-impregnated pressure-cast sleeveless aluminum block in conjunction with Reynolds Metals. The block by itself was actually a good design in street applications, but other issues would quickly neuter any benefits it brought to the table. The GM 2300 engine would also be Chevrolet’s first OHC, but was purposefully designed for low-RPM torque (to feel like a V8) as opposed to making its horsepower at high-RPMs like European engines.
The Corporate 2300 engine may have had initial potential, but quickly became a cascading failure – emissions compliance and cost pressures dictated switching from the Chevrolet-developed aluminum cross-flow head to a hastily-redesigned cast-iron lump, which in turn led to higher NVH (noise, vibration, harshness) because the engine was now top-heavy (which amplified inherent roughness due to the engine’s long-stroke design). This was “solved” by using softer engine mounts that in turn led to carburetor mounting screws backing out on their own from excessive vibration – this caused backfires and poor mileage from the resulting vacuum leaks. Additionally, Ed Cole initially pushed for air cooling, believing the aluminum block would radiate sufficient heat on its own. It only took one seized test engine to disabuse him of this idea, and a traditional radiator and water pump were hastily added – yet another failure cascade in the making, as no provision was made for an overflow tank; the base engine radiator was not much bigger than a sheet of letter-size paper, and the coolant level in the radiator was below the highest coolant cavities in the engine which could lead to air pockets and hot spots. Add to that early problems with failing head gaskets and overheating was the result. Valve stem seals that dried out and cracked caused excessive oil consumption on top of all that. Needless to say, while the block itself may have been well thought out, the rest of the engine design was a pigs breakfast, and it would take GM until 1976 to finally revise the engine to the point it was reliable by standards of the day.
But that was all in the future at this point…
In August 1969, only six months after inheriting Project XP-887 and with early 2300 prototype engines racking up miles, DeLorean directed Jim Musser to contact London-based Cosworth Engineering to determine interest in developing a racing engine based on the 2300’s aluminum block.
Cosworth had been founded in 1958 by Mike Costin and Keith Duckworth (both former employees of Lotus Engineering Ltd.) and initially focused on tuning, primarily of the Ford 105E Anglia engine. By 1962, they were producing modified Ford 109E engines for installation in the Lotus 7.
In 1967, Duckworth signed the Ford-Cosworth agreement that launched the DFV (Double Four Valve) engine that would go on to become one of the most successful Formula One engines of all time. Driver Jim Clark observed about the DFV engine, “When the power comes in at 6,500 rpm, it does so with such a bang that the car is almost uncontrollable … you either have power or you haven’t.” Despite the binary power output, Clark would cross the finish 27 seconds ahead of the second place car in his first outing with the DVF – the first of 176 wins over 18 seasons for the engine.
In 1969, Cosworth launched the DOHC 16-valve BDA (Belt Drive, Series A) – their first mass-produced road engine that powered the Ford Escort. It would quickly be modified for Rallye use, where it enjoyed great success in Junior categories such as Formula Atlantic and Formula 2. But Cosworth were beginning to realize they were at the limit of developing the cast iron BDA further. In fact, Duckworth had been contemplating a new 2-liter aluminium race engine, and warmly received the invitation from Musser to review the GM 2300 engine. A trip was made to Detroit in late 1969 and Duckworth was impressed with the engine’s materials technology and deep-skirt design – it was just the type of block he felt he could design a competitive engine around, and an agreement was signed with GM soon thereafter.
Chevrolet Design Engineer C.E. “Cal” Wade, who had been involved in Chevy racing efforts for 25 years, subsequently traveled to England in early 1970 to begin collaborative work on the racing variant engine, which Cosworth designated “EAA” (also sometimes referred to as “EA”). The street variant of the engine was referred to as the “Vega TC” (Twin Cam). When I bought Cosworth Vega #2196, I was delighted to find a Xerox copy of this report in the documentation that came with the car, generated by Wade in 1971 – it provides interesting detail I’d not seen before on the development of the program.
Bare 2300 blocks began to arrive at Cosworth in the Autumn of 1970, just as Vega was being launched in the US, with a prototype EAA engine generating horsepower for the first time in March, 1971.
The Chevy-Cosworth EAA engine made about 270HP @ 9,000 RPM, which was competitive for the intended Formula 2 application. The race engine was destroked to 2 liters (1,995cc) to comply with Formula 2 requirements, and utilized a crossflow DOHC 4-valve head with pent roof combustion chambers, forged pistons, 11.5:1 compression ratio, dual Weber carbs, dry sump and Lucas fuel injection and ignition systems. Early GM computer models predicted 190 HP (gross) @ 7,600 RPM for the detuned Vega TC street engine, with 0–60 MPH times in the low-mid 8-second range and quarter-mile times in the low-16-second range with an approximate 125 MPH terminal speed. It’s important to note that the street engine was developed from the race engine and utilized virtually the same head and cams – it truly was a race-bred engine!
DeLorean’s strategy presumed the lightweight Cosworth EAA engine would dominate racing results, subsequently creating a halo effect for Chevrolet.
At DeLorean’s request, a feasibility study for the Vega TC street version was done that indicated a potential market of around 30,000 cars – certainly high enough to justify creation of the street variant, but keep in mind this was done during Vega’s first year on the market and before its initial quality issues were widely known. DeLorean subsequently authorized Wade to build a prototype Cosworth Vega engine. A meager budget, and resistance from managers between Wade and DeLorean meant low priority for the project and relatively slow progress.
Wade’s report provides some detail on the different carb and fuel injection systems that were considered. Also of interest is the notation about a new exhaust manifold and addition of an A.I.R. pump to meet Federal emissions regulations.
This early stock photo from GM was used in several car magazine articles and clearly shows a cast-iron exhaust manifold. Production street engines were instead fitted with a tubular stainless steel header – the most expensive exhaust component in GM’s parts books during the Cosworth Vega’s run.
The Bendix system would be the first use of electronic fuel injection (EFI) on a Chevrolet and became the critical path in the Vega TC’s production schedule.
Had things come together as planned, the Vega Twin Cam would have been introduced in late 1972 for the 1973 model year. The first prototype Vega Twin Cam cars were built in June, 1971, about the same time Chevrolet added the Vega GT option to the price list. The prototype street engines used dual Weber-Holley two-barrel carburetors and made about 170 HP (gross).