Vintage SCI Dual Road Test: 1957 Corvettes, Dual Quad Carbs and Fuel Injected – Fast and…Fast

posted at the Cohort by LeSabretoothTiger

Our survey of 1957 sports cars and GT cars wouldn’t be complete without the Corvette, especially since that year was a big one for America’s plastic fantastic guided missile. The new larger 283 cubic inch V8 was the big news to start with, but then Chevy upped the ante by making it available with fuel injection. Rated at 283 hp at a very zippy 6,200 rpm, it instantly made the Corvette the fastest regular production car in the world, at least in a straight line. But there was a cheaper to fly in 1957 too, with the 270 hp dual quad (two four barrel carburetors) version.

SCI took both of them to task, wringing them out to find out just what this new-fangled fuel injection brought to the pavement, other than burnt rubber.

Given the modest production numbers, it would have been extremely unlikely to find two Corvettes that were similarly equipped except for the engines. The FI version had a couple of advantages, other than its induction system: it was lighter (at 2840 lbs) due to only having a hardtop, and it had a slightly steeper rear axle ratio of 3.70 whereas the carburated car had a soft top and a 3.55 axle ratio. And both had the standard close-ratio Saginaw three speed manual transmission, as the new Borg-Warner T-10 four speed did not arrive until later in the model year (April) (CC’s history on early Corvette transmissions here).

The base price of the Corvette was $3176 ($29k adjusted). The 270 hp dual quad option cost $182.95 ($1685 adjusted), and the 283 hp FI option cost $484 ($4456 adjusted), although apparently that price jumped quite a bit later in the year. The 13 extra horses for the FI were pricey ones, $23 each ($212 adjusted), so presumably it was more than just the additional power and bragging rights from the Fuel Injection emblems on all four sides of the car.

The article starts off with an interesting historical tidbit: That Chevrolet madly rushed the Rochester FI to market for the 1957 model year because it was naturally concerned about the collective impact of Plymouth and Ford’s all-new cars on its passenger car line sales. “The decision to bring out the fuel injection was made very, very late in 1956—virtually on the introduction deadline. At that time it was still what engineers call a ‘breadboard layout’—a combination of of units that work together but aren’t fully developed…

That would also apply equally to the electronically-controlled Bendix “Electrojector” fuel injection system that was also touted by Chrysler and Rambler in 1957, and which quickly had to be withdrawn due to being seriously underdevelopment. GM obviously made the right choice by going with a fully mechanical system, as electronic components were not yet reliable under the hood in 1957.


The dual quad car started readily, although flooding could be an issue on a hot start. It idled low enough, but very lumpily, due to the competition cam. That would be the “Duntov cam”, named after the Corvette’s god father, although he didn’t actually design it, just prodded the engineers to do so.

But the downsides of the carbs soon became apparent: after a fast run, idle “was extremely bad, and after each stop in the braking test, the carbs would stall the engine dead”.

The FI car started instantly when cold. Idle was quite high, at 1200rpm even after warmup. But it was easy enough to adjust it, and SCI could get theirs to idle at the same 500 rpm as the carb car, although they decided to leave it at a higher 950 rpm, as these engines produce very little torque at low speeds due to the cam.

The throttle linkage on both cars came in for heavy criticism, which made the carb car particularly difficult to modulate, as throttle response was inconsistent and unpredictable. This is where the FI really shone: despite the limitations of the throttle linkage, throttle response was instantaneous. “It’s as though there’s a system of levers between the throttle pedal and your back. press the throttle a little bit, and your back is pressed, NOW, to the same extent. Slam the throttle down, and your back is slammed, NOW, to the same extent, even in high gear.

Although the dual quad car’s performance was generally similar, the experience of the instantaneous response put the FI car in a different league. Zero flat spots. A take off in top gear resulted in a perfectly smooth run, and in a mere 13.8 seconds, as good or better than many sporty cars of the time. And none of the gasping for fuel in hard corners, a typically common problem with carbs and their fuel bowls.

Let’s get to the meat: their respective acceleration performance. I’ve cropped the key table here, for your faster viewing pleasure. The FI version has lead, in just about every metric except for the dash to 100, and speed through the 1/4 mile traps. It’s hard to say just why, given the intrinsic variables even between even two identical engines off the assembly line. The FI is very fast indeed, but the dual quad is right there too. Clearly the injected version went about its business in a more crisp and concise manner.

And also more efficient, at least in hard driving, yielding a whopping 12.0 mpg compared to 10.5. Given that the FI car had a lower rear axle, that is a meaningful difference. Average driving yielded a closer 13.6 to 13.8 mpg difference. Fuel efficient these cars were not, with their low axles gearing and no overdrive.

Here’s a snippet from GM’s Heritage Archive that shows both gross and net power ratings for all of the ’57 Corvette engines. Of course that doesn’t necessarily mean it’s all 100% accurate; for instance the 283 hp FI engine is widely considered to actually have made about 290 gross hp, which is what it was rated at for 1958-1961, without any apparent changes. And some claim that the 270 hp dual quad was sandbagged too. An interesting anomaly is that the dual quad engine’s peak net hp comes in at 6,000 rpm, the same as its gross, whereas the FI’s net is arrived at 5,600 rpm. I’m quite sure I’ve never seen an engine’s net rating be at the same rpm as the gross, since the gross rating was derived with open headers, among other things.

What this chart does point out is that the 250 hp FI 283 made more torque than the others, and at a more usable speed for typical driving. It would be the one to have gotten for a daily driver, except for bragging rights or competition, red light or track. I’ve seen some performance numbers attributed to the 250 hp version that were quite close to the 270/283 hp units.



Of course all that additional power did the Corvette’s simple Hotchkiss rear suspension no favors. Full power starts were were accompanied with axle bounce and shake: “It took a delicate balance between engine revs and deliberate clutch slippage to provide a smooth yet catapulting get-away. The rear end is also the main weak point in the Corvette’s handling…all that’s needed to bust that rear wheel loose is a little more roll, a little tighter corner, a bit more speed or a bumpy surface.”

The Corvette’s steering was not a strong suit either: “is just quick enough to get out of most troubles, but the strong caster action means you have to work to do it. This is responsiveness to muscle, not will.”  And the close-to-the-chest steering wheel position made rapid steering corrections difficult. The seating position in the C1 was never ideal, one of the number of limitations of its less than stellar birth.

And unsurprisingly, the brakes weren’t any too hot either, except for when they got too hot and faded. “...brakes, which are an omnipresent menace in this otherwise capable road car”. It should be pointed out that in 1957, when Chevrolet got serious about the Corvette’s track chops, numerous HD components were options, including sintered metallic brake linings, which were a huge improvement, once they got up to operating temperature. One could even specify a race-ready (EN Code) version of the Corvette, with all the critical components and without a heater.

The article ends with wishful thinking that did not come to be: “We hope that some of the research going into the Sebring SSR project will be diverted into production channels…the chassis is just at the end of its string., while the engine and injection have a great future ahead of them. The 1957 Corvette may be the link between two eras”.

That was Zora Arkus Duntov’s great hope too, for a truly new Corvette with a world class chassis to live up to its world class drive train. And it was in the works in 1957 for 1960, the Corvette Q concept, with a super light space frame, rear transaxle and fully independent suspension. It would have been the most advanced and superlative sports car in the world, but the recession of 1958 but the kibbosh on that ambitious undertaking. Instead, the venerable C1 soldiered on through 1962, and the C2 that replaced was still not as advanced and light as what the Q would have been.

The ’57 fuel injected Corvette became collectible from day, thanks to its superior power, limited production (1,040 were built), and the significantly cleaner styling compared to the overwrought ’58, universally accepted as the least desirable of the C1s. It was a superlative drive train looking for a better chassis, but even with its limitations, it sent a strong signal to the sports car world that America was going to play too, and with gusto.


Related reading:

1957 Fuel Injected 283 V8: Ahead Of Its Time and the Competition

Vintage R&T Review: 1954 Corvette

From Powerglide to Four Speed – The History of Transmissions On Early Corvettes