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SPORTS CAR ILLUSTRATED (CAR AND DRIVER) 12/60 No one knows Corvettes like Zora Arkus-Duntov, the highly practical driver-designer who's project engineer for the Chevrolet's sports car. His views on the development of the latest Corvettes are of great import: "Originally, our plan was to develop the car along separate touring and racing lines, as Jaguar did with the XK series on one hand and the C-Type and D-Type on the other. With this in mind we first introduced racing options, then the SR2, finally the SS, which was intended to be our `prototype' competition car. When this project was cut off, we realized we had to approach the Corvette in some other way. Since we could no longer build two kinds of Corvettes with different characteristics, we decided to give the Corvette buyer as much of both worlds as we could - to use our racing experience to combine in one automobile the comfort of a tourer and the ability of a racer. A big order, yes, but an interesting and worthwhile one. The 1960 Corvette was the first to reflect this thinking; the 1961 car is very similar." Before talking to Mr. Duntov about the 1961 Corvette, SCI had formed this strong general impression of it; one of the most remarkable marriages of touring comfort and violent performance we have ever enjoyed, especially at the price. That our impression matched Chevy's intention so exactly is a tribute to the job done by Duntov and his crew. We had ample time to sample the latest Corvette and get to know its virtues and vices, yet could complete the rigorous R.R.R. routine in time to publish this report scant weeks after its introduction. Unique dispensation by Chevrolet made this possible. In mid-August, well before official release, we picked up production Corvette number three in Detroit, drove it to New York for testing at Lime Rock Park and our other test areas, and returned it to the Motor City. Altogether SCI drove this automobile almost 1900 miles. Since this red and cream machine was equipped with the hottest engine on the long list of Corvette options, it's no surprise that we were stunned - as in earlier Corvette tests - by its terrific performance. It was equipped with the Duntov cam and Rochester fuel injection, the latter always being accompanied by special cylinder heads. Therein lies a tale. As is well known, last year Chevrolet introduced aluminum cylinder heads for the fuel-injected engines. In addition to the change in material, there were important design alterations which accounted for the gain of 25 bhp over the previous 290 bhp rating. For better breathing the intake valve head size was increased from 1.72 inches to 1.94 inches, which was helpful but which couldn't boost power unless matching improvements were made in the intake port. It couldn't be enlarged all the way through because the pushrods pass close to the ports near their outer ends, so the port was necked down to a venturi shape adjacent to the pushrod holes, then allowed to expand smoothly on its way to the combustion chamber. It works very well. The alloy used for these 1960 heads contained a high percentage of silicon, an amount not specified by GM but certainly in the 16 to 20 percent bracket - sufficient, anyway, to make inserted valve seats unnecessary. The casting method used was the same low-pressure system now used for the Corvair heads and other parts in which the molten alloy flows up into the mold from below, under moderate pressure. The casting is an intricate one, and the high-silicon alloys tend to be difficult to handle, with the unfortunate result in Chevy's case that there were frequent faults in the castings and consequently a high rate of rejection. It did happen that and occasional head managed to conceal a flaw through all the inspections and smuggle it aboard a Corvette; this was one of the two prime causes of the field failures that gave these heads a poor reputation. The other cause was overheating. If for some reason a Corvette's cooling system failed or lost water, the aluminum heads, with their lower melting point, were much more likely to be damaged than were iron heads. If you had a set of sound aluminum heads, then, and kept your cooling system in good order, you had absolutely nothing to worry about. Many Corvette owners racing with aluminum heads today will bear this out. But that high rejection rate, plus the frequency of field failure, led Chevy to decide to stop supplying the heads in 1961, and to replace them with cast iron heads that incorporate the same refinements to the intake tracts. These iron heads were given their baptism on the Cunningham Corvetttes at Le Mans last June, and are now supplied on the 1961 fuel injection engines. To get those added horses at the top end, this engine obviously has to breathe more air, which could be supplied by increasing the area of the intake venturi. Doing this, however, would weaken the metering signal at low and medium speeds, much the way a large carb venturi brings on low-speed metering problems. Duntov says that the extra air was needed for short periods only at very high engine speeds so Chevy built in a reserve supply by increasing the height of the "dog house" of the fuel injection unit. The fins were trimmed off the top, which was raised almost an inch to increase the volume of the plenum chamber inside. (The cross-section on page 46 shows the 1957 engine with the finned manifold, drawings of later engines being unavailable.) The ram pipes keep their original 12-inch length in the course of this change, which was made in 1960. Another important change in the engine department is the use on all 1961 Corvettes of the Harrison aluminum radiator fitted only with the Duntov-cam engine last year. Once you know how, starting the fuel-injected Chevy engine is a snap either cold or warm. In the former case you leave your foot off the gas; in the latter you press the pedal to the floor. A fast-idle setting is in effect when the engine's cold, and, like any good injected engine, it runs smoothly and regularly right from the start. As smoothly and regularly as it ever will, in this case, for the warmed-up 850-rpm idle is definitely rough. With solid tappets and 66 degrees of overlap this is hardly surprising, and Duntov points out that the post-1960 increase in intake valve size had the effect of aggravating the slight roughness that existed earlier. It also makes the unit a little easier to stall if you don't apply enough gas. Throttle response is excellent - instant, proportional to pedal position, and cutting off power effectively on the over-run. Above we're talking about response in terms of control. Response in terms of a kick in the back is sudden and convincing. The broad range of power offered by this remarkable V8 is extremely impressive; credit must be given the big valving at the top end and the injection over the rest of the range. No matter what gear you're in or what speed you're going, you can step down hard and get the same surging lunge forward. As the Engine Flexibility graph shows, the powerplant pulls smoothly and strongly from idle right on out to the redline, which is marked on the tach at 6500. We used 6500 for our acceleration runs, through Duntov feels you get equally good results by shifting at 6000. So well are these special-cam engines assembled and balanced that you can, if necessary, look at 7000 or even 7500, something we didn't try and Chevrolet didn't encourage. Appropriately for a sports car, this engine is exciting to listen to. Along with the new back end shape, the twin tail pipes have been redirected so they angle outward just behind the rear wheels. They rumble with a truly musical motorboat tone and beat a tattoo on the sides of the cars you (frequently) pass. As the revs rise, the tone ranges up through several octaves to a musical moan that emanates more from the engine than from the exhaust. In short: a hard, solid, machine-like sound that inspires confidence. At or near idle speed, especially with the top up, a vibration period materialized on our test Corvette that set up a "thrumming" within the cockpit. The new, more forward location of the exhaust outlets also seemed to make the exhaust more audible in the cockpit than on earlier versions, something that makes you think the engine is revving faster than if should at cruising speeds. The sound can become as tiring on a long trip as t is fun on a short one. By any standard at all, the Corvette we tested is a sensational performer. Right up to 60 mph, in fact, its curve traces an arc much like that of the 250/GT Ferrari (The Corvette took 6.7 seconds against the Ferrari's 6.6). Unlike the Ferrari, the Corvette goes all the way to 60 in first gear, then after the shift to second the curves begin to diverge as the Ferrari's lighter weight and superior aerodynamics make their effect felt. Yet the Ferrari had a vibrant, restless air about it that was constantly urging you to put your right foot down and go. Not so the Corvette, which is just as happy pottering along byways at more sedate velocities. On this car, there were four speeds available but it never seemed to matter which one we were in . Our trips back and forth to Detroit could have been made all in first gear or all in fourth gear, for example, still keeping up with the traffic. Just for amusement, we took some rough acceleration times to sixty in each of the gears, using one gear only each time. In second it took about 8 second, in third about 10, and in fourth gear only a little less than 15! It is certainly not the intent of Chevrolet that you should not shift this transmission, however. It's one of the quickest, slickest shifts available today on any automobile. Its short, plastic-knobbed lever is spring-loaded to the right side of its very narrow gate, and the movement of lever and linkage is light and easy. If you're really forcing shifts through in a hurry, though, you'll find that you'll be hung up for just an instant as the very positive synchromesh does its job. This is in contrast to Porsche-type synchro, for example, which allows you to push your way past the synchronizing mechanism to save fractions of a second in competition. The ratios are high and close, as the step percentages show, and all the indirect gears emit the same, just-audible gear whine. An excellent feature is the T-handled lockout for reverse gear. A major gearbox improvement for 1961 is the use, finally, of the aluminum case for the four-speed unit that was first tried on the SS back in 1957. The new case pares off 15 pounds, and is bolted up against the aluminum bell housing that is now supplied with all manual-shift Corvettes. Within the housing is a clutch that performed smoothly and reliably through all our testing. Its pedal travel is long and light, and its engagement was always clean and solid. It's reassuring to know that a clutch redesign program back in early 1957 produced a unit that's safe up to 10,000 rpm - in emergencies. During our acceleration runs the optional Positraction differential proved its worth by leaving twin black streaks of equal length on Lime Rock's asphalt. It also greatly aids control by power when cornering. This Corvette was equipped as a hot "boulevard" machine, having the most potent engine but with standard brakes and tubeless whitewall tires. Bringing the car to a halt after a few of those scalding 0-100 runs quickly induced fade that was marked enough to cause alarm. Fortunately, the brakes recovered very quickly, with no grabbing, pulling or other signs of damage. But they are definitely not nearly up to the car's performance. To get suitable brakes, you'd select Regular Production Option 686, which combines sintered iron linings with the standard drums. RPO 687 goes all the way with a finned, fan-equipped drum and scoops in the backing plates, still using the sintered iron linings. The grabby, unpredictable ceramic-metallic linings are now a thing of the past, having served their purpose as a stopgap until Moraine could design sufficient life and consistency into the sintered iron type. Finally, at the end of its development life, the original Corvette has been endowed with handling that allows its ample power to be used for control, in both street and race track trim. How? By making street and race chassis trim identical! This policy began in the 1960 model year, when the optional stiff suspension kits were discontinued, and the standard suspension was stiffened in roll by removing the original kink in the 13/16-inch front anti-roll bar and fitting a 5/8-inch anti-roll bar at the rear. This trim is unchanged for `61. The only suspension change that Duntov would recommend for a competition Corvette is exceedingly subtle; take out the stock rubber bushings in the front anti-roll bar mountings and linkage, and insert bushings of harder rubber. This will reduce lost motion in the anti-roll bar's action, effectively increasing the front-end roll resistance and biasing the Corvette's handling toward harder, faster cornering. The result of this basic change is a real improvement in Corvette handling. It sits flatter, making entering and leaving corners a less tricky maneuver than before. As the steering Behavior graph shows, the Corvette understeers, requiring more and more steering lock as speed increases, but it's by no means as gross an understeerer as earlier version, which (in street trim) would simply plow right off the road as power was applied. Now power can be used to bring the tail end out when cornering fast, reflecting a much better balance between front and rear suspensions. When either end of the Corvette does swing out in a corner, it swings pretty quickly and without much warning, so some vigilance is required. Properly set up on the right line, the `61 Corvette can get through a corner with impressive speed. The kicker is "properly". If you select a conventional line, applying power in the usual way, you'll find that the car will plow out very wide at the exit and you'll be wondering if you have strength enough to haul it into line. Under these conditions it can be a real handful. To get through easily, it's necessary to set up for the corner earlier, steer hard into the bend earlier - much as if the bend were tighter that is actually is, and apply power sooner. Done right, this will bring the Corvette out fast and clean, with much less effort. This willingness to work well on one line but not so well on others means that choices of position, in or near a corner. He's either on the proper line or very slow or in trouble. The suspension changes have made the car much more susceptible to power control, giving the driver another dimension in which to operate, but this new realm is still very strictly bounded. During our handling tests, we found that the steering now transmits a small but useful amount of information to the driver regarding the adhesion at the front wheels, and has a minimum of lost motion. Without a doubt, the slightly faster steering ratio, supplied with RPO 687, would be just right for fast cornering. The stock ratio is slow for sporting driving but fine for touring. It's a basically better car to drive now, also, because Chevrolet has steadily improved the driving position over the years. No longer must the steering wheel be placed right under the chin. Progressive improvements in seat design and travel have given the driver a lot more room, if not a continental arm's-length position. Trimly upholstered with a new narrow ribbing, the Corvette seats are easy to get into and out of, over a wide door sill, but offer (as a corollary) very little lateral support to the occupants. We felt that the seats were placed more "flat" than they might be for maximum thigh and back support, but we realize that any more rearward angle would cause interference between thighs and steering wheel. The arm rests on the elaborately-trimmed doors are placed so they don't interfere with the driver's movements; in general there's a lot more room where it counts than in early Corvettes. Far too decorative in design, the dashboard still manages to convey some useful information. The big 160-mph speedometer carries no resettable trip odometer, surprisingly for a car that's so popular for rallies, and suffers from a needle that wavers uncertainly and lags substantially under hard acceleration. The fuel gauge, and functions connected with it, annoyed us considerably. To begin with, the Corvette's standard tank holds only 16.4 gallons. You can get a 24-gallon fiberglass tank, but it fills up the top well and makes a hardtop mandatory. At a cruising mileage of 16 miles per gallon, the stock tank would allow a range of 260 miles-none too generous. The fuel gauge indicates "empty" with about 4 gallons remaining, though, which makes the brow break out with sweat after only 200 miles. Speaking practically, we found we filled up about every 160 miles during our test, and inconveniently short interval for a car designed for long-distance fast touring. In addition, the fuel tank is not easy to fill, and near the top the gauge isn't proportional in its readings, causing the needle to drop to a 3/4 reading after you drive around the block from the gas station. We're not upset about the mileage, which is as good as one can expect from a car of this performance. It's just that the car does everything it can to keep your thoughts on gasoline at least 50 percent of the time. This includes a gas tank vent that percolated in hot weather and wafted fumes into the nearby cockpit. On a car as fast as this one, or even a machine approaching its speed, nothing is more important to safety and stability than controls that work smoothly and effectively. For this reason we took a dim view when the accelerator pedal started doing tricks - namely staying about 3/4 on when we backed off. Investigation showed that the pedal is held to the floor by two rounded studs which snap into holes in its rubber surface, these studs doing double-duty as guides and hinge points. On this car one of these studs would snap out when we tromped down hard, as when starting a warm engine, leaving a flopping pedal which would stick "on". When it worked properly, the accelerator gave smooth and proportional control, but this kind of sloppy assembly of such an important component was inexcusable. Long - legged drivers will appreciate the extra inch of seat travel that can be supplied on order. Our Corvette had only the soft top, which folds so neatly into its covered compartment behind the seats. When putting the top up, we found it works best to clamp the two front latches first, then the two on the back deck. The latter engage with surprisingly fragile loops from the rear top rail, which doesn't exactly mate tightly with the rear deck. We weren't able to check the top's rain-resistance, but there were a few stray breezes with the windows rolled up tight. Vision with the top up is blocked off in a big way in the two rear quarter areas, and the plastic rear window has the usual ripples. Draft-free ventilation is practically impossible to arrange since there are no quarter-windows next to the "old-fashioned" wraparound windshield. The cowl vent lets in lots of air, which beats down on the shins at speed in a way that can become tiring. Fitted with a two-speed fan, the heating and defrosting system has more than enough power for this small interior. The only major styling change for 1961 is the new tail, which most observers approved heartily. Its tucked-in lines mate well with the original shape, and even seem to increase the usable luggage volume. Comparing the 1961 Corvette with a 1957-vintage car, one is surprised at how complete a change has been effected over the years. When the dual headlight treatment arrived, for example, the width of the hood opening was radically reduced, making work on the engine - especially spark plug changing - much more difficult. Buried down on the right side, the battery is hard to reach too. Generally, Chevy is happy with the way the fiberglass construction has worked out, one important advantage being the absolute absence of rust and the resulting high value of a used Corvette. Studies have also confirmed that integral construction (the only alternative now being considered by our industry) isn't as effective for an open car as the present frame and body layout, especially on a weight basis. So it appears that future Corvettes will stay with the present method of construction. Like most General Motors cars, the Corvette boasts remarkably good detail finish, and approach that can be an asset to a sports machine. Control handles like the hand brake and hood release have handsome lettering with an impressive burnished chrome finish; other details are dealt with just as deftly. But the styling, in spite of the renovated tail, dates from an era when design effort was concentrated on the simulation of devices and effects that were mechanical in appearance but not necessarily automotive or operational: phony louvers, scoops, jet pods here and there, dashboards that sought to confuse rather than clarify. Aerodynamics are important, certainly on a car this fast, but we realize more and more that in the automotive speed ranges there's ample room for styling with in an aerodynamic area. We're glad to observe a general trend in our industry toward styling idioms that are automotive, once again, and relatively restrained in nature. The Valiant and Corvair are two excellent examples of this trend away from airplane and rocket ship orientation. Now that Chevrolet has completed its family of Corvairs, we expect the next project will be a new Corvette. With the experience they've gained with this car, and in view of the trend toward sensible styling and sensational engineering, the next Corvette should be a hum-dinger. All they have to do is put the same emphasis on doing things that they have in the past on seeming to do things. Since this 1961 Corvette already does more than most drivers can handle, that's an exciting prospect. - SCI
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TOP Owners of 1960 Corvettes who may be thinking of buying new models of this versatile Detroit sportscar will find the `61 little changed. The front and rear styling facelifts constitute the visual changes, while mechanically, except for some new special-interest options, the car is much as it was. Styling changes on the fiberglass-bodied convertible concern themselves with a moderately altered grille and a sharp horizontal line that breaks across the rear deck. Some will like it and others won't, but it is an application of elements from "dream Corvette" prototypes. The Corvette engine, which has become a staple for hot rodders and special sportscar builders, is offered once again with a wide variety of options. Standard on the 283-cubic-inch V-8 powerplant is a single four-barrel carburetor and 9.5-to-1 compression. The demanding customer can match components to suit his taste, whether it be stoplight racing, touring, roadracing or the drags. A manifold with two four-barrel carbs, fuel injection and the special Duntov cam are only a few of the power and speed options. Of less general interest but vital to racing fans are the fluid-drive limited-rpm cooling fan and a cross-flow aluminum radiator. The radiator option is important for cooling the special-cam engine. Bearing inserts rated as heavy-duty are included with the most powerful engine, along with outside air ducting to the engine compartment. Transmission options are the same as offered in 1960. Standard is the three-speed manual; the remarkably smooth and sturdy four-speed all-synchro is available as is a two-speed Powerglide. A large variety of differential ratios may be ordered with either the conventional or limited-slip rear end. Suspension will be as good as ever, with the 1960 improvements retained. A heavy front stabilizer bar is standard, and quick steering is optional, to be used primarily for road racing. Rear suspension consists of leaf springs and radius rods to take the high torque loads put out by the engine. A link-type stabilizer gives lateral stability, while shocks have a nitrogen filled envelope within the liquid reservoir to prevent hydraulic fluid aeration during rapid shock travel. The brakes, which have always been excellent, will be of molded asbestos; an optional competition package utilizes sintered iron linings which offer high heat dissipation for racing. Unlike the earlier racing linings, these require no warm-up before becoming effective, and they stop in a straight line. Amazingly enough, the sintered linings have 57 square inches less lining material than the asbestos, yet do a superior job under adverse conditions. For just plain fun motoring, the use to which most Corvettes are put, the luxury options once again include the popular removable hard top, radio, heater and power windows. The list of Corvette fans will continue to grow in 1961.
FULL RANGE ROAD TEST The only mass-produced sports car manufactured in the U.S. is the distinction still retained by the Corvette. In all of its many forms it definitely possesses the characteristics and personality necessary to bear the sports car label. It matters not whether someone wants a two-seater merely for transportation, or an all-out racing machine - there is a Corvette to fit his desires, no matter how extreme. In order to sample at least a couple of Corvette variations, we tested two automobiles that were identical except for color and engine option. The more conservative of the two, ironically, was painted a bright red both inside and out - even the carpeting and upholstering matched the paint. Specifically, all that made it more conservative was the installation of the mild, 230-hp engine which is the lowest-powered unit available. The more sedate-appearing white test car displayed an identical interior except for one important instrument panel feature, a tachometer red-lined at 6500 rpm instead of 5300. Even before the key is turned to start the engine, this sliver of red is a dead giveaway that a 315-hp fuel-injection engine lies ahead of the four-speed gearbox. This power and drive train package, though similar to previous years, received some important alterations in the 1961 version. Intake valves and ports were both enlarged to improve breathing and help raise the output from the previous maximum of 290 hp. The superb four-speed gearbox, fitted to both cars, now has a completely aluminum case instead of just using the light metal in the tail-shaft housing An under-hood view reveals one other important area in which aluminum is now being used - the radiator and top tank. The tank is divorced from the radiator and is bracketed to the engine, allowing a more graceful hood slope. In this case the use of aluminum cut the radiator weight in half. Seated in the cockpit, a 1961 underbody contour change becomes apparent - the transmission hump has been narrowed to that the driver's right leg and throttle foot don't appear to be as cramped. The instrument panel is still one of the very few that contain a full complement of instruments. The only warning light that appear are for the hand brake and high beam of the headlights. The brake light is a new addition for 1961; both lights spell out their purposes luminously, so that even an unfamiliar driver will understand their purposes. The centrally-located tachometer is in a very practical position, just ahead of the steering wheel hub. Forward and higher, the speedometer dominates the center of the panel proper. In certain types of competition events it would be nice if the tach and speedo could trade places, so that the rev counter could be bigger. Driving both corvettes definitely demonstrated that their character is very much the sports variety, even though they are very plush vehicles. Tufted carpeting and considerable use of chrome trim, including pattern chromed teardrop-shaped panels attached to the doors and kick pads, create an air of luxury. When you grasp the steering wheel and negotiate a turn at high speed, and when you shift the four-speed gearbox, you completely lose sight of your luxurious environment and realize that you are driving a true sports car. Both test cars were not fitted with power steering, so they inspired a feeling of confidence when cornering. The fast steering ratio, which required a little better than 3.5 turns of the steering wheel from lock-to-lock, might be too stiff for some of the more delicate members of the fair sex, but any driver that appreciates the security of having maximum feel of the car will be very happy with it. For those that don't wish to flex their muscles, power steering is available. No matter what you pay for a sports car, whether it be in the four-figure or five-figure bracket, there is none that shifts more easily and more consistently than the Corvette four-speed box. Being synchromesh in all forward speeds, all gears can be selected in any sequence of up- or down-shifting without gear clash. The best feature of all is the reverse gear lockout, which is controlled by lifting a couple of prongs on the side of the shift lever about two inches below the knob. It is impossible to shift into reverse unless these prongs are raised, so one need never fear hitting reverse when shifting into first. Without the lockout, many drivers have a tendency to move the lever too far to the right in their avoidance of reverse, with the net result that the lever gets hung up between first and third, so we can't offer enough praise for this device. The Corvette's cornering ability is definitely in the superior category, and for many reasons. The car has a fairly low center of gravity, moderately stiff suspension and a stiff front stabilizer bar. Engineering wisely sacrificed softness of ride for safety in this machine. The body appears to lean a minimum amount during fast cornering, probably because of the heavy torsional stabilizer bar and lighter unit of the same type on the rear suspension. Though this rear bar doubtless contributes to a flat cornering, it has a detrimental effect on rear wheel adhesion. In a hard corner it has a tendency to take weight off the inside rear wheel, causing the outside rear wheel to be called upon to offer the majority of the resistance to side thrust. This is not good racing practice for power-on cornering. In actual driving, though the back end wasn't uncontrollable, it did start drifting earlier than the other characteristics of the car would indicate. One of the pleasantest things about cornering a Corvette with the 315-hp engine is the behavior of the fuel-injection system. Since it is not dependent on its float bowl level for fuel metering as in a four-barrel carburetor, it acts completely insensitive to motion. In maneuvers that would cause a four-barrel-equipped engine to lose power or die completely, the fuel-injected engine purrs like nothing was happening. Due to the fact that injector nozzles spray the fuel into the sports, much larger throttle openings can be tolerated at low rpm than with carburetion. One simple butterfly is all that is necessary to control the system instead of a complex of progressive linkage and many throttles. Port distribution also eliminates the necessity for a heat riser, thereby improving volumetric efficiency by allowing a cooler, more dense charge to enter the cylinder. When comparing the performance of the two engine options tested, we should not lose sight of the fact that the difference goes far beyond the single area of carburetion. Though all Corvette engines have a displacement of 283 cubic inches, there is much that is done in the way of altering breathing ability to produce variations in output. The mildest engine is fitted with a hydraulic-lifter cam that limits rpm to the passenger car range and provides only 250 degrees of valve-opening duration on both the intake and exhaust valves. An overlap duration of 28 degrees in conjunction with the use of a four barrel carburetor makes the 230-hp engine behave like the best-mannered passenger car. The 315-hp engine absolutely won't idle under 700 rpm and is most consistent in the 800-to-900-rpm range because of the combined effects of 66 degrees of valve overlap and the inability of the fuel-injection system to maintain pressure within its lines at low rpm. The overall duration of the engine's cam provides both valves with 287 degrees of opening. Due to the 72-degree late closing of intake valves in the hotter engine, plus more accurate fuel distribution from the injection system, an 11-to-1 compression ratio requires no special concessions whatsoever. The short timing and carburetion system of the mildest engine limits its compression to a 9.5-to-1 ratio. A good comparison of the performance potential of the two cars cannot be gained by merely comparing their low-speed and mid-range performance figures, because there really isn't a large numerical difference. However, a time of 8.3 seconds 0-to-60 mpg for the mild engine as compared to 7.4 seconds for the hot version will impress those that have experience in the field of acceleration testing. A quarter-mile run would show a very large difference between the two. In all ranges of acceleration, both cars would make more impressive showings if they had special tires and rear end gears more favorable than 3.70-to-1. This is actually the smallest ratio available in a Corvette, equipped as the test cars were, with a four-speed transmission and limited-slip differential combination. Though our road test dealt only with the mildest and hottest engines available, there are three other optional powerplant choices possible: a 245-hp, 270-hp and a 275-hp. The most conservative of the three is the same as the 230-hp engine, except that it is fitted with dual-four-barrel carburetion. The 270-hp engine follows the same trend, but in addition to the carburetion a longer-duration mechanical-lifter cam replaces the hydraulic assembly of the two milder engines. At the other end of the list, the 275-hp option is the same as the hottest fuel-injection job. It shares the same 11-to-1 compression but uses a mild hydraulic-lifter cam. Three transmissions are available with the two mildest engines: a three-speed, four-speed and Powerglide. The three hottest engines can be ordered only with the three-speed or four-speed boxes because of their fast idle speeds. Mechanical options aren't the only ones available, nor have we listed all of them - convenience items like power assists, convertible tops and removable hard tops make it possible to order a Corvette to fit any individual preference. Motor Trend/September 1961
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TOP Once upon a time, just a few years ago, owners of America's only sports car were on the receiving which held that the only thing the beast had to offer was drag strip performance. It would go like the wind (in a straight line, they said), but it wouldn't corner, it wouldn't stop, it had a boulevard ride, and a glass body. And it took 265 cu in. (4.5 liters) to get that performance. Well, these derogatory remarks probably were true at one time. At least, some of them were. But Chevrolet engineers have now achieved an excellent package, combining acceleration, stopping power, a good ride and handling characteristics whose adequacy is indicated by the car's race-winning ways. In our January 1959 test report of the 1959 Corvette we said that 1960 would be the year for big changes in the Corvette. We were wrong. The 1960 model wasn't too much different from, or too much better than, the 1959 version. Lacking any great changes in 1960, we might logically have predicted a major change in 1961, but luckily we didn't. However, the few changes which have been made are for the better. Continual refinements since 1954 have made the Corvette into a sports car for which no owner need make excuses. It goes, it stops, and it corners. The major change in the appearance is the rear end treatment, which was derived from the Sting Ray, GM racing Corvette, owned by Bill Mitchell. The stubbier lok achieves a more crisp and a fleeter appearance than that of previous models, which looked "soft." The front end remains basically unchanged. New bumpers fore and aft blend nicely into the body design, and the exhaust tips are now under the body instead of through the bumper tips. This was a good move; there's no mistaking the Corvette for any other make and it is a better looking car now. The finish of the fiberglass body is generally excellent, although we did find a few minor flaws on our test car, mostly in obscure places. Panel fit and fairing from one panel to another were good and showed Chevrolet's geat attention to the Corvette molds. Interior trim and design are similar to past models and well done, but have a little of the Motorama touch. The seats are excellently designed and are very comfortable. Our longest single excursion was of some 200 miles, but no sign of driver fatigue was evident and we honestly feel a day behind the wheel of a Corvette could be put in without undue strain. The instruments are easy to read and include a speedometer, tach (reading to 7000 rpm - red-lined at 6200), gas gauge, temperature gauge, oil pressure gauge and ammeter. Indicator lights are used for the turn signals, highg headlight beam and parking brake. The parking brake light on the panel lights up when the key is turned on (if, of course, the parking brake is on) and when the engine is started the light blinks its warning to the driver. The only fixture in the Corvette interior that's had to use is the radio, which is mounted in a console deep under the instrument panel. This console also carries the clock, which is difficult to see and should be looked at only when the car is stopped. The seats have 3 in. of fore and aft movement, which gave everyone on our staff adequate leg room, but the body panel between the seats interferes with the driver's elbow (when shifting) when the weat is at its rearmost position. Vision in the Corvette is excellent when the car is equipped with the hardtop. Slim pillars and lots of glass area are responsible. We used two test cars, one white and one metallic blue. Reflections from the white rear deck into the rear window of the white car caused a hazy view when we looked out of the back window or used the rear view mirror. The darker colored car did not give us this trouble. Even in the white Corvette no haze was noticeable in the windshield, because the cowl was covered with red material to match the upholstery. We noticed a considerable amount of wind noise with the windows rolled down, and if the windows are rolled up they have to be all the way up or the driver feels a bad draft. Some engine and wind noise was evident even with both windows up. The car started with a flick of the key on cool mornings but, oddly, it was difficult to start on several occasions after the car had been thoroughly warmed up. This is unusual and could most likely be cured by further tuning. [note: the Car and Driver article explained that a warm car is started by pressing the accelerator to the floor.] The clutch operation proved extremely smooth, whether we were plugging along in slow-moving traffic or getting off the line for a standing start acceleration run. We tried a stop and start on a hill of approximately 30% grade and found that by dextrous manipulation of the clutch and throttle it could be surmounted with ease and smoothness. We hadn't been worried about a lack of horsepower, but we had wondered about the flexibility of the engine until we tried the hill. Once more we found the injector to be extremely flexible. The engine is able to pull smoothly from under 15 mph to top speed with no bucking or hesitation. In our test car, which had 4.11:1 rear axle gears, it was much easier, of course, than it would have been with the top ratio available. Flexibility, rather than acturl increased power, is the main justification for the injectors and in road racing use they allow full power to be maintained under all conditions. Carburetors will almost invariably starve when the car turns one way and flood when it corners in the opposite direction; and quite often they will flood under extreme deceleration, making it difficult for the driveer to accelerate properly out of the turn. Options for 1961 include five horsepower ratings: 230 (standard), with a single 4-barrel carburetor; 245, with twin 4-barrels; 270, with twin 4-barrels; 275, with fuel injection; and 315, with fuel injection. Three transmission options are available: 3-speed synchromesh; 4-speed synchromesh, and Powerglide. Five rear axle ratios are available: 4.56:1, 4.11:1, 3.70:1, 3.55:1 and 3.36:1. Obviously, any buyer should find a combination to suit his needs. Performance of this Corvette was little different from the one we tested two years ago and only improved at the upper end. A similar car, owned by Alan Lockwood, race tuned, timed 107 mph at the end of a quarter mile at the LADS drag strip, Long Beach, Calif. We've said many times that we think the Corvette 4-speed transmission is one of the best in the world and we have no reason to change our minds. In all, five different people on our staff drove the car and none was able to fault the synchromesh. The ratios are excellently spaced and, with synchromesh on all four gears, the driver always has the proper ratio at his disposal by a mere movement of the lever. We were greatly impressed by the combination of a very good ride coupled with little roll on corners. Most cars with riding qualities approaching those of the Corvette can't match its sticking ability on curves. And those that match or beat its handling usually ride like the proverbial truck. The Corvette is absolutely unmatched for performance per dollar in terms of transportation machinery (some of the newer Formula Junior cars will beat it for performance per dollar, but are, of course, single purpose cars). The steering is accuate, though a little slower than we would like in a car with this much power and speed. The brakes proved up to every test we put them to and a sudden panic stop to avoid a day-dreaming motorist increased our admiration for the refinements and improvements made by Chevrolet engineers in the Corvette since its introduction. Once again we want to thank Harry Mann Chevrolet for furnishing the test car. The following weekend the Corvette was used as the pace car at the Riverside Sports Car GP. |
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