The third generation was patterned after the "Mako Shark II" concept car. The C3 was introduced for the 1968 model year and lasted through 1982, and at 15 years was the longest running Corvette generation. It came out on top of the performance era of the 60's, sold in record numbers through the EPA rules and gas crunch of the 70's, and stood its ground against its competition into the early 80's.
It saw monikers now revived such as LT-1, ZR-1, and Collector Edition. It became the first Indy 500 pace car and celebrated Corvette's 25th anniversary with a limited edition Indy Pace Car replica and a two-tone Silver Anniversary Edition.
The "Sting Ray" nameplate was not used on the 1968 model, however Chevrolet still referred to the Corvette as a Sting Ray, and 1969 models had "Stingray" fender nameplates. The 350 cu in (5.7 L) engine replaced the 327 cu in (5.4 L) engine in 1969, and it was the only year for a C3 side exhaust option. (right) 1969 was also the only year the all-aluminum ZL-1 427 cu in (7 L) was available.
The special big-block engine was reported to produce 550 horsepower and only 2 cars so-equipped were produced. In 1970 small-block power peaked with the optional high compression, high revving LT-1 producing 370 hp (276 kW). The 1971 and 1972 LT-1 was rated at 330 hp (246 kW). 1971 was the 454 big block's peak in power with the 425 hp (317 kW) LS6 rating.
An even more powerful LS7 454 CID engine rated at 465 hp (347 kW) was planned and even included in early GM assembly manuals, but was never installed in any production cars. The ZR1 special engine package was an option available exclusively with the LT-1 engine option. It included the solid-lifter small-block engine, heavy-duty four-speed transmission, power brakes, aluminum radiator, and a revised suspension with special springs, shocks, stabilizer bar, and spindle-strut shafts.
Only 53 1970-1972 ZR1's were built the 427 big block was enlarged to 454 cu in (7.4 L). The ZR2 special engine package was a (1-year only) option released in 1971. It included equipment for the big-block LS-6 engine. Only 12 were built.
In 1972, GM moved to the SAE Net measurement for power (away from the previous SAE Gross standard), a more realistic rating which included installing all the power consuming accessories (alt. fan, water pump) and mufflers on the engine during testing which resulted in lower HP values . Along with lowered compression ratios from 1971 in anticipation of unleaded fuel, emission controls, and catalytic converters in 1975, power continued to decline and bottomed out in 1975 — the base ZQ3 engine produced just 165 hp (123 kW), and the optional L82 engine produced 205 hp (153 kW).
1973 Corvette Stingray Coupe
By 1973 the Corvette had been around for an amazing 20 years. During those 20 years it remained very much a sports car, although it did get a little softer as the years passed by. And it also became a little more raw than most sports cars at the same time. The Corvette has always been bigger than it needed to be, and by 1972 it had grown externally once again with no gain in useful inside space or access.
There was no more racing, not even under the various guises of the past. The ultra-performance engines were gone. Most important, the '73 Corvette was not the exciting new Corvette, not the mid-engine car GM had
promised. But it wasn't all bad news. The 1973 iteration hadn't grown much from the 1972. Its nose was extended to accommodate a deformable covering for a sturdier bumper that was displaced rearward in a 5-mph impact with a barrier, but that added only 2.2 in. to total length - not much for a bumper. The '73 Corvette was only 35 lb heavier than a comparable 1970 model with the same equipment (air conditioning, power-assisted steering, etc).
The major change for 1973 was in the tires. For several years Corvettes came with Corvette-only tires, built to specifications drawn up by Corvette engineers. These were of conventional bias construction at first, then bias-belted when other sports cars had changed over to radials. For 1973 the Corvette finally had radial tires, from either Goodyear or Firestone. The change was not altogether desired by the Corvette people, but tiremakers showed a lack of interest in continuing to build a specialized tire for the Corvette and there was no problem getting steel-belt radials of the right size. So it was done, with some gains and some losses. Cornering power was reduced, braking distances increased and the tires used were rated for a lower cruising speed, down from 140 to 120 mph. This last item was probably academic for all but a handful of buyers, but for all it was bad for the image. Tire life was better, the car was more stable at speed, and wet-weather grip was improved.
American Racing Equipment Alloy Wheels
A new option for 1973 was a set of American Racing Equipment alloy wheels in 15x8 size. They were attractive and did reduce unsprung weight, but their chief attraction was that they reduced total weight by 8 lb per wheel and 40 lb per set. The 1973 car had guard beams in the doors and added insulation all over, along with the heavier bumpers, so to be strictly accurate the car gained 75 lb and these wheels allow it to lose 40. There were three choices of engine this year; the standard 190-bhp 350 V-8, the giant 454 V-8 with 275 bhp and more weight, and the high-performance 350 with somewhat higher compression ratio, different camshaft and 250 bhp. Our test car had the latter engine, mated to the close-ratio 4-speed manual transmission and the highest numerical final-drive ratio in the catalog, all the better for maximum acceleration.
This engine and transmission worked well together. The L82 (that was the option number for the engine) made the Corvette competitively quick - not so quick as the former race-based versions but more than quick enough to be up with other high-priced sports and GT cars. This engine could be bought with air conditioning, which the old racy engines could not have. And the 1973 engine did well in terms of drivability. No stumbles, no surge, thanks largely to the use of an air pump to controlled emissions instead of relying entirely on lean carburetion and retarded ignition.
The close gearing was perfect for this engine, with an overall ratio in 1st low enough to make comfortable starts from rest and intermediate ratios that kept the engine close to peak power during acceleration. There was a choice here, because the engine had a wide range of torque and would pull strongly from 1500 to 5600 rpm. You could leap from 1st to 4th, zoom around town in 2nd or 3rd, putter along in 4th at low speed, or whatever you wish. And the gearshift was uniquely light for the size of the gears it shifted. The controls were also light, adding up to a car that was easy to drive quickly and smoothly.
But not quietly; the Corvette's noise level was still that of a sports car, to be sure. The 1973, when compared with a 1971 LT-1 Corvette (last of the mechanical-lifter engines and the line equivalent of the current L82) was actually louder at idle, booming 73 dBA compared to 60, and the 1973 peaked at a thunderous 100 dBA in 1st gear because of strong induction and exhaust noise. The 1971 car peaked at 94 dBA. At steady speeds, however, when noise level was more critical, the 1973 car was quieter: 74 vs 76 dBA at 30 mph, 73 vs 78 at 50 and 78 vs 81 at 70. What seemed strange to many road testers was that Chevrolet had an objection to the previously noisier tires - but then went and made their car a whole lot more noisy.
The radial tires were intimately involved with the new car's ride and handling. There wasn't much body roll and only a little under-steer. The Corvette was a satisfying drive on a winding road, and in the wet they new tires showed a marked improvement over the old, particularly in the steering which was more responsive. The suspension was tuned to the tires and the ride was less harsh - still perhaps not enough suspension travel, but better than on any previous Corvette. Braking distances were also adversely affected; they increased from average to not-quite-average (for the era). This was not such a good thing for a car with so much speed.
Inside the 1973 Corvette
The Corvette interior been changed very little for 1973. Some of the holdovers were poor - the location of the wiper-washer switch, the limited access to the limited luggage space and the typically clumsy GM buckle for the separate lap and shoulder belts. The fiber-optics light monitors were gone (not much loss) and it was nice, looking out across the hood, to realize that the silly hatch cover for the wipers were gone. Generally, the driver was well accommodated. Most of the controls and switches were within easy reach, there were enough instruments and the tidy little vinyl-rim steering wheel didn't block view of them. Still no adjustment for the seatback, but there was plenty of legroom and with the optional adjustable steering column the wheel could be moved up and down and back and forth.
Having only two seats allowed the shoulder strap (which was on an inertia reel) to be threaded through a slot in the seatback, just above the shoulder - a nice arrangement. In all, the Corvette was a reasonably comfortable place to sit for hours. For all its age, size and compromises, if the Corvette was equipped with the right options it was a pleasant and rewarding car to drive, and the 1973 model was one of the best Corvettes ever.
1974 Corvette Stingray Coupe
Styling changed subtly over the generation and minor trim changes occurred through the 1972 model. An aluminum wheel option (left) was seen on '73 and '74 pilot cars but was withheld for quality issues and wouldn't be available until the 1976 model year. In 1973, due to government regulations, the Corvette's chrome front bumper was changed to a 5-mile-per-hour (8 km/h) bumper system with a urethane cover. The rear chrome bumpers remained unchanged. In 1974, a 5-mile-per-hour (8 km/h) rear bumper system replaced the chrome bumpers and matched last year's front system with a 2-piece urethane cover with recessed tailights. 1975 saw the last year for the convertible, which did not return until 1986.
In 1977, Dave McLellan succeeded Zora Duntov as the Corvette's Chief Engineer. In that year, the word Stingray was no longer used, ending the 13 year run where the names Corvette, Sting Ray and Stingray were synonymous. 1978 saw a 25th "Silver Anniversary" edition, the first Corvette Indy Pace Car, the introduction of a "fast back" glass rear window, and a new interior and dashboard.
The highest production year was 1979, and would last up to the C5 model. In 1980, the Corvette received an integrated aerodynamic redesign that resulted in a significant reduction in drag. In 1982, an opening rear hatch was offered for the first time exclusively on the Collectors Edition. A new engine featuring cross fire injection, a fuel injection carburetor hybrid, was also introduced that year as the L83. It was the only engine available in 1982, and was not offered with a manual transmission.
Power in 1982 was the 200 hp (149 kW) L83 engine. Early model years came standard with an innovative Fiber-Optic light monitoring system. Strands of fiber optic wire went from the center console to the headlights, turn signals, tail lights and license plate light monitoring a total of nine lights. It was discontinued after the 1971 model year.