Rumor has it that Chevrolet lost money on every Corvette it made until 1963, but General Motors is pretty cagey about its finances so nothing is known for sure. Whatever the case, when the new 265 V-8 was fitted into the '55 models, the car began to be potentially competitive. However, it wasn't until 1957 that the Corvette became a force to be reckoned with on the track. I got a chance to take a ride in one of these cars recently, and was duly impressed.
Unlike in many sports cars of the period, there was plenty of room for my 6'2" frame. My knees were bent at a comfortable angle, and I could move around in the seat. Visibility through the wraparound windshield was superb. After a couple of adjustments to the mirrors, I was ready to roll. I gave the gas pedal a tap, turned the key, and the engine lit up on queue. At first, as it warmed up, it ran a little rich, and then settled into that inimitable American V-8 throb. It took a minute to familiarize myself with the standard three-speed again, but the clutch was firm, and the car leapt away from a standing start even with modest throttle.
With the optional 4:11 rearend, the close ratio gearbox, and a two four-barrel-equipped 283 V-8, I was able to reach the California speed limit in a hurry in second gear without drama. Of course, everybody on the freeway wanted a better look at the car; some grinned and waved, or gave me the thumbs-up. Handling the car was two-fisted and masculine, especially when you are on the edge with those 6:70x15-inch bias-ply Firestones. But cornering was flat and sure with just a bit of understeer, somewhat like a dirt track sprinter, but the ride was not unduly harsh. No matter how much throttle I gave the car, the torque of the Chevy small-block just seemed to keep on pulling. I backed off before the boys in blue decided to make inquiries.
The optional Borg Warner T-10 four-speed would provide a little more latitude for gearing down, but the close ratio three-speed our car was equipped with shifted comfortably and cleanly. Breaking the rear tires loose was easy with the 283 and two four-barrels pulling us around, but then this was an era of four-wheel drifts and machines that could easily be overdriven if you didn't know what you were doing.
Corvette's first major restyle came in 1956, so there was not much impetus to change the look again in 1957. The new design for 1956 included an all-new body, outside door handles, roll-up windows, and an optional removable hardtop for the first time. Many people consider the '56 -'57 roadsters to be the most beautiful Corvettes up to that time, with their clean lines and Lebaron sweep, scooped-out front fenders. Others would say it was the most beautiful Corvette ever built with its clean form-follows-function bodywork.
From all outward appearances the '57 Corvette is indistinguishable from the '56 model. In fact, the only easy way to tell from the outside without opening the hood is by examining the inside rearview mirror. On the '56 model, it adjusts with a thumbscrew; on the 1957, adjustment requires a wrench to loosen the locknut. The truly dramatic changes in the '57 Corvette were the improvements in its running gear.
Chevrolet's 265 V-8, which made its debut in 1955, was bored out in 1957 to give it a 283ci displacement, though the stroke remained the same. The engine could be equipped with a single four-barrel, two four-barrels, or at midyear, the new Rochester fuel injection that allowed the engine to produce the fabled one horsepower per cubic inch-a domain that until that time was reserved for the likes of Indianapolis race cars.
By 1957, competition among the big three was hot, and all of them had new V-8 engines. So to get the racer's edge, management at Chevrolet knew they had to go one better. Supercharging was considered, but the heat and internal stresses that would place on the engine were obviously a big downside. On the other hand, hot rodders in the United States had been playing around with fuel injection for years, but it had never been considered for production cars up until that time.
With no time to lose if they wanted it for the '57 lineup, the GM engineering team of John Dolza and Zora Arkus Duntov, with help from GM's Rochester carburetor division, went to work on a continuous-flow fuel-injection system in early 1956. adding to the design problems was the fact that Duntov had lost control of a hardtop Corvette he had taken around the GM proving grounds for tests and wound up in a ditch. Seatbelts were not part of the safety equipment back then, and, as a result, Duntov slammed into the top of the car when it flipped and broke a vertebra in his back. This meant for the next six months Duntov had to work standing up, trapped in a full body cast, in order for the system to be debuted on the '57 models. In an astoundingly short time, the engineers came up with a system that was relatively inexpensive to make, but promised significantly more power over conventional carburetors.
At first, when the prototype injected engine was dynoed, it didn't produce any more horsepower than the dual-carbureted model. But much more was at stake in developing the fuel-injection system than the Corvette. Chevrolet's larger, more popular cars were to get fuel injection too. And there were many popular stock car races to be won. "Win on Sunday, sell on Monday" was a truism in the industry at the time, and in the late '50s competition was fierce.
Ultimately, the designers and GM's Rochester Division crafted its Ramjet system, which raised engine top end horsepower, and also helped produce more power and torque in the low- and mid-range. Modifications were made to the "fuelie" engine, such as solid lifters instead of hydraulics that could be prone to valve float, and longer reach spark plugs with metal deflection shields to protect from manifold heat.
The tops of the blocks were reinforced to prevent cylinder wall distortion problems due to over-tightening of head bolts, and a new distributor was added with its breaker points positioned immediately above its shaft bearing to prevent wobble fluctuations in the point's gap. Fuel port runners and the ram's horn exhaust manifolds were modified to take advantage of the scavenging effects of the high overlap cam.
When all was said and done, a '57 Corvette equipped with fuel injection, the Borg Warner T10 all-synchromesh transmission, and 4:11 gears in the rear could do 0-60 mph in 5.7 seconds and 0-100 in 16.8 seconds, with a top speed of 132 mph. Impressive indeed for the time.
This performance combined with the RPO 684 competition performance package that included heavier springs, shocks and anti-sway bars, 16.3:1 quick ratio steering, Posi-traction limited-slip differential, special brake cooling, and ceramic brake linings made for a formidable opponent to go up against the much more expensive European cars, such as the Mercedes 300 SL, the D jaguars, and even the Ferraris of the era.
Corvette had finally hit on the winning combination. Of course, only 240 out of the 6,339 Corvettes produced in 1957 came with fuel injection, and relatively few had the four-speed T10 transmission introduced in midyear. However the car was equipped, it was a fun car to drive, with performance enough to scare all but the most resolute and committed. Our test car had neither feature, but was still a real brawler on the road.
Unfortunately, racing had become progressively more dangerous, and the '55 crash of Pierre Levegh into the crowd at Le Mans that killed over 80 spectators had put a damper on factory racing to the point where the AMA (Automobile Manufacturer's Association) banned all factory sponsorship in 1957, just when Corvette was poised to make a real name for itself. Of course, Corvettes were raced privately, and Duntov continued his efforts out the back door at GM, but it wouldn't be until 1963 that General Motors would get into officially racing again.
But that was then and this is now, and if anything, our red '57 Corvette roadster is a bigger hit today than it was in its own time. Sporting around town in this stunning classic, nimbly out performing most of the modern iron is just as big a thrill as it was 49 years ago. The sound, smell, and feel of an open roadster with all the horsepower you can use is hard to beat. The '57 Corvettes weren't cheap when they were new, and they are not cheap now, but they were worth every penny of the sales price then and still are at today's prices.
This exceptional '57 belongs to Ray Najjar of Thousand Oaks, California. He is only the third owner of this immaculate example. Ray purchased the numbers-matching car five years ago as a show car project, but discovered that it was just too good to be restored. oddly enough, this rare, original, dual-quad car with a three-speed standard tranny and a 4:11 rearend was sold with heater and radio deletes instead of these common accessories.
Ray says he loves driving the car, but his wife prefers his '06 model because of its creature comforts and amenities. "It's a handful to drive with its solid axle and drum brakes all around, but it is certainly exciting, and everywhere we go people have to stop and look at the car. Its original bias-ply tires don't grip the road the way modern radials do either. But one thing I really like is, I can still tinker with this car because it's all right out there where you can get at it in the engine compartment. With my 2006, I had to buy the six-year maintenance contract. I'll never sell the '57. It'll go to my son, and perhaps grandsons."
'57 Corvette by the Numbers
Engine: 283 ci
Transmission: Three-Speed Saginaw
Engine Code suffix: EG
Casting No.: 3731548
Casting No.: 3740997 (Cast Iron)
Intake/Exhaust Valve Size: 1.72/1.50
Combustion Chamber: 55.6685
Intake Manifold (Aluminum)
Casting No.: 3739653
2x4 Carter WCFB
Casting (Left Hand) No.: 3733975
Casting (Right Hand) No.: 3733976
Stamping No.: 1110891
Engine/HP/Application: 283/270 HP
Housing: Cast Iron Bowl Distributor
Notes: No Vacuum Advance, Standpipe Oiler
1102043 30 Amp Std., Tach Drive
Three-Speed Saginaw (Close Ratio)
Maincase: Cast Iron
Tailhousing: Cast Iron
Maincase No.: 3845122 All
Tailhousing No.: 3737450
Sidecover No.: 3731911
Special Information: This tailhousing transmission is different on Passenger and Corvette. The Corvette tailhousing has three tapped holes cast into the housing to accept the Corvette-only floor shifter. All Passenger models used the column shifter. Early 1957 No. 3737450 tailhousings do not have casting dated codes. Later tailhousings are dated in the same way as are the maincases. Very early '57 Corvette three-speed transmissions carried the No. 3722946 tailhousing, which was a non-vented, non-dated tailhousing. The No. 3730450 was initially vented, but not dated until mid-April of 1957 when dates were added to the left side of the casting.
1957 Rear Axles
All '57 Corvette rear axles are stamped with an alpha-numeric code, which identifies the build source, axle ratio, and date of manufacture.
The axle code is located on the front right or passenger side of the differential carrier at the same height as the axle tube. The axle code will read from left to right or bottom to top. The prefix or two-letter code designates the gear ratio and any other specific information about that rear differential. This code also refers to the manufacturer or source which built the rearend.
The numbers following the letter prefix designate the calendar month and day that axle was produced. From the 1955 through 1962 model years the calendar month was designated by a one-number code from January (1) through September (9). The October through December codes were designated as 10-12 respectively. Beginning with the '63 model year, all month designations begin with a "0" so the January date code would show "01" instead of "1" as in previous years.
|Month Code Designations |
|1 ||January |
|2 ||February |
|3 ||March |
|4 ||April |
|5 ||May |
|6 ||June |
|7 ||July |
|8 ||August |
|9 ||September |
|10 ||October |
|11 ||November |
|12 ||December |
|Plant Codes |
|G = ||Detroit Gear & Axle |
|Example: ||AE-409 |
|AE = ||3.36:1 Axle assembly for Powerglide Corvette built at Detroit Gear and Axle |
|4 = ||Month: April |
|09 = ||Day: 9th day |
|1957 Corvette Rear Axle Codes |
|Series: 2934 |
|Ratio ||Descrip. ||Code ||Source |
|3.36:1 ||Powerglide ||AE ||G |
|3.70:1 ||Manual ||AH ||G |
|3.70:1 Posi ||Manual ||AN ||G |
|4.11:1 Posi ||Manual ||AP ||G |
|4.56:1 Posi ||Manual ||AQ ||G |
|3.70:1 Posi ||Manual ||AS* ||G |
|4.11:1 Posi ||Manual ||AT* ||G |
|4.56:1 Posi ||Manual ||AU* ||G |
These rear axles were part of number 684 option code released approximately 3/1/57, which included heavy-duty brakes and suspensions.
From Corvette by the Numbers by Alan Colvin, used with permission of Robert Bentley Publishers.