Originally published in Sports Cars Illustrated magazine in June 1957.
Chevrolet’s injection is a premature baby, but it’s still alive and kicking. It was prematured by a sudden jolt from the collective Plymouth and Ford styling departments, and without a major body change Chev needed a potent sales weapon. The decision to bring out 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 units that work properly, but aren’t fully developed and integrated into one mechanism. It’s still very much that way. Moreover, the Rochester engineers are very competent carburetor designers, but didn’t have nearly enough time to adapt their techniques to the wholly different problems of injection. In spite of the fact that the new arrival had long been expected, its arrival was not without complications.
The above are facts, but in spite of them the Chevy “Ramjet” constant-flow injector works very well indeed. The big question, of course, is: How does it stack up against carbs? To find out, we set up a full transcontinental ’57 Corvette road test, involving our entire testing staff. On the West Coast an injected machine was obtained from the factory representatives, while on the East Coast a dual-quad version was provided by Alvin Schwartz Chevrolet and Shelly Spindel, of Brooklyn.
As a result we have a lot of the answers, but not all, the doubt being due to slight variations between the cars tested, the injected car, with the hardtop alone, weighed 120 pounds less than the carbed machine, which was toting the more complex soft top mechanism. Also, rear end ratios were 3.70 with the injector and 3.55 with the carbs. Advantage is taken of the better fuel distribution of FI by upping the compression ratio to 10.5/1, while the standard car had 9.5/1. This is a logical follow-up step, and does not “favor” the injection so far as our tests are concerned. The same can’t be said of the weight and rear end discrepancies, which would tend to help the FI car at the bottom end, though very slightly.
Starting the dual-quad car was easy, by twisting the ignition switch, though some care was needed to avoid flooding on hot starts. Once warmed up, the idle was low enough at 500 rpm, but it was full of lumps and shook the car bodily. This can be handed to the competition cam, which was installed in both cars and checks out as seen in the sidebar.
The power from this cam comes on strongly at about 2700 rpm and stays that way until about 5300, after which it falls off rapidly, apparently due to valve gear. At the end of a fast run, the idle was extremely bad, and after each stop in the braking test the carbs would stall the engine dead. The dual-quad setup is by now a familiar one, so rigged that the rear carb runs all the time and the front one cuts in only at about 2/3 throttle.
The engine was cold when we first twisted the switch on the Ramjet Corvette, but the engine caught on the first spin, bursting into a wholesome clatter of solid tappets jingling at a warmup idle at 1400 rpm. We raised the hood and studied the injection system. It looked purposeful but very different from the racing-type setups we know best…at present. A tiny copper tube, about the diameter of a pencil lead, runs from the pump to each of the nozzles which are located on the manifold at each of the intake ports. The tubes look fragile. We looked with distrust on solenoids, diaphragms, flex-cable drive, and complex linkages each of which might be a point of failure.
The single throttle body and venturi are not in accord with American ideas on racing injection, but resemble both carburetor practice and overseas applications. It’s no handicap, as long as the orifice is big enough, and as long as ram intake tubes can be accommodated, and it gives very good metering for a wide operating range.
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