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1968-1972 Chevrolet Corvette

1970 Chevrolet Corvette

Chevrolet issued another evolutionary Stingray for 1970. A United Automobile Workers strike forced a two-month extension of '69 production, which gave Chevy the time it needed to make the 1970 Chevrolet Corvette a better-built car, and was doubtless a factor in 1969's record volume. But the strike also delayed the '70s from reaching dealer showrooms until February, which pushed Corvette output to its lowest model year total since 1962 -- just 17,316 units.

Cosmetic changes were slight. The extreme bodyside tuck-under was found to be susceptible to stone damage, so Chevy flared the aft portions of each wheel opening, which helped somewhat. The grille went from horizontal bars to a fine eggcrate pattern. (The real radiator air intakes, Duntov's original slots, remained on the car's underside.) The eggcrate look also appeared on the front fenders in place of the previous four "gills." Front parking lamps switched from small, round units to rectangular fixtures with clear lenses and amber bulbs. The dual exhaust outlets also shifted from round to rectangular.

The 1970 Chevrolet Corvette was the last of the big-power Corvette models.
The 1970 Chevrolet Corvette was the last of the
big-power Corvette models.

Inside, seats were reshaped for better lateral support, more headroom, and easier access to the trunk. Shoulder belts, still separate from the lap belts, got inertia storage reels, thus ending some cockpit clutter. A Deluxe Interior package was added to the options list, comprising leather seats, full cut-pile carpeting, and ersatz wood trim on console and doors. Some people liked it, but purists sneered that the fake wood made the Corvette seem too much like the new Monte Carlo personal luxury hardtop coupe.

Engines were again the main Corvette news for 1970. The 300- and 350-bhp small-blocks returned unchanged, but they had a new companion, the solid-lifter LT1. Although listed for '69, the $447.60 option wasn't available until 1970, owing to development and manufacturing problems. It was right in line with Duntov's longtime goal of minimizing weight in a performance car growing ever heavier with more creature comforts. Unlike tamer 350-cube engines, the LT1 had more radical cam timing with more generous valve overlap, used the big-block mill's fat 2.5-inch-diameter exhaust system, breathed through the same 850-cfm Holley carb fitted to the L88/ZL1, and came with transistorized ignition.

When originally announced, the LT1 was listed at a sedate 330 bhp at 6000 rpm and torque at 380 pound/feet at 4000 rpm. But when 1970 Corvette catalogs reached print, it was rated at 370 bhp. The typical example could streak through the standing quarter-mile in 14.2 seconds at 102 mph, comparable to big-block performance of just a few years before. Visual identification was subtle -- just a special domed hood with perimeter striping and discreet "LT1" lettering -- but there was no mistaking the rap-rap exhaust or the distinct tapping of mechanical lifters.

Meanwhile, big-block buyers got a 427 stroked out to a full 4.00 inches and 454 cid. Two versions were listed, one real, the other not. The former -- RPO LS5 -- offered hydraulic lifters, 10.25:1 compression, a single four-barrel carb, a fairly modest 390 bhp at 4800 rpm, and a massive 500 pound/feet of torque. Listed but never installed in production 'Vettes was RPO LS7, with an aluminum block and heads, mechanical lifters, 11.25:1 compression, higher-lift cam, and transistorized ignition. Depending on your source, output was either 460 or 465 bhp.

Like the previous year's enlarged small-block, the bigger big-block for 1970 was a response to the increasing stranglehold of emissions tuning. Also like the 350, the 454 produced less power per cubic inch than its predecessor, but a lower peak power speed made it some-what torquier and thus more flexible at low rpm.

The only test report of an LS7 'Vette seems to be that of Paul Van Valkenburgh, who drove the first one built from Los Angeles to Detroit in December 1969 for Sports Car Graphic. Reporting a standing quarter-mile of 13.8 seconds at 108 mph, he enthused that 'this car gives the impression that it could do anything you demanded... Never have we tested a car with such a secure speed potential." It was hardly refined -- "like taxiing a DC3 at full throttle up and down a freshly plowed runway." Maybe it was just as well that Chevy didn't run off many copies, because the LS5 version was smoother, vet almost as thrilling. Road & Track tried one with the automatic and obtained 7.0 seconds for the 0-60-mph run, a 15.0-second quarter at 93 mph, and a top speed of 144 mph.

The three-speed manual transmission was no longer offered on Corvettes. Turbo Hydra-Matic usage was scaled back a bit, too; 350-horse and LT1 small-blocks could be had only with either of the two four-speed stickshifts. Posi-traction and tinted glass became standard equipment.

As it turned out, 1970 would be the beginning of the end for big-inch, big-power Corvettes in the traditional mold. Besides skyrocketing insurance premiums and fast-falling demand for hot cars generally, they were doomed by GM president Ed Cole's desire to eliminate low-volume options and to retune all his company's engines for 91-octane fuel, correctly anticipating the catalytic converter that he knew would be needed to meet ever-tightening emissions limits. Cole also ordered that beginning in 1971, all GM divisions would quote engine outputs in SAE net measure rather than the usual gross figures, which did not reflect power losses to engine accessories, mufflers, and other components.

The results were steadily decreasing compression and lower outputs for engines with more realistic power ratings that only made them seem punier still.

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