Chevrolet Corvette C-3 427 Coupe

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Chevrolet Corvette C3 427 Coupe

1968 - 1982
5356 - 7000 cc
250-560 bhp
3/4 spd. man 2 spd. auto
Top Speed:
189 - 233 km/h
Number Built:
45,456 s.block 72,418 b.block
4 star
Chevrolet's Corvette today ranks just one notch below immortality on America's list of mechanical achievements. Every working aspect and every styling feature evolved from Chevrolet's plan to build the ultimate American car. Then and now, the Corvette was exciting, it stimulated all of the base emotion lurking deep in modern man.

It was a car that appealed to the young at heart. A car that could help you lose your driving license very quickly indeed. A certain rapport exists between all Corvette owners and one procedure is common to all, a tradition that seems to have travelled through the generations - owners never make reference to their cars but always to their Corvettes.

The 1968 Corvette was a radical departure from the previous C2 model. In comparison, it looked brutal, masculine, with a shape that suggested a slightly overweight Group 7 sports racer or one of the Le Mans Ferraris when they were winning. The shape screamed power (and testostorone), and why not, with a 400-horsepower 427 cu. in. engine this was one hell of a machine.

It was true that the 400 hp engine was no different than the one offered in 1967, except for the mandatory air pump apparatus for emission control. Three 2-bbl. Holley carburetors were used, with the one in the middle providing for normal operation while the end ones, with their vacuum operated throttles, were useful for setting land speed records and snaffling speeding tickets.

If you drove the 427 Vette around town, you would soon realise how good the system really was. The center carburetor let the engine idle at 750rpm and then pull away smoothly in any gear with no fuss. The operation of the secondaries was nowhere near so predictable. These would work on a pre-determined system governed by air flow through the primary carburetor, the end carburetors snapping open with a great sucking roar and the Corvette would lurch forward with gusto.

Thankfully there was normally a short lag before the vacuum-operated secondaries opened themselves, giving enough time to brace the neck muscles so your head would not bend over the seat to view through the rear window. Road testers did note this was less of an issue when the engine had warmed for an hour or so - some considered this a problem but there are not many places we would rather waste an hour than behind the wheel of a Vette.

The Corvette 427 could complete the quarter in 14.1 seconds - at 102 mph. Very respectable figures for the 1960's, but in any case if you were in the car it always sounded and felt much faster. You could option the 427 with a 3.70 axle which Chevrolet called a "Special Purpose Ratio", which probably translated to (legal) "street racing". Understandable when you consider that with the standard 3.36 ratio the Corvette would still be in third gear at the end of the quarter.

We have been told that the combination of reduced grille opening and the air pump for exhaust emission control produced cooling problems on the early models. That may explain why the Owner's Manual warns that normal operating temperature should be 210°F. Early cars also had (we are told) a very noisy fan, which indicates GM were trying to solve the problem by pushing more air through the radiator. There are certain advantages to high coolant temperatures, such as improved thermal efficiency and reduced crankcase dilution, provided overheating can be avoided on extremely hot days. The only disadvantage (provided the engine would not overhead of couse) would be additional heat being transmitted to the passenger compartment. Remember the Vette was made of fiberglass, so there was not too much seperating you from 700 pounds of 210° F cast iron!

Very few changes were made in the drivetrain and chassis from the previous model, but that would only be a fault if they were inadequate, which they wern't. The transmission was, for the time, near perfect - with a well-balanced, sturdy-feeling linkage that built confidence. The clutch effort was light considering the torque it had to cope with. While road testers reported that shifting was easy and pleasant, the close ratio transmission and the 460 Ibs'/ft. of torque made it seldom necessary. Even so, we assume most still changed gear just so they could enjoy the experience of driving arguably the worlds then greatest sports car.

There was one down side however. Vigorous shifts into fourth gear could go awry, because the designers built in a hazard in the form of a forward-facing console-mounted hand brake. Some bemonaned the fact that the Corvette designers had never been able to find a satisfactory place for their hand brake lever. Before '67 it was mounted under the dash and when set, tended to bash the entering driver's knee. On the C3 they mounted it between the seats and pointed it right at the shift knob. If you make a rapid 3-4 shift, the kind Corvettes encouraged, the brake lever would carve a neat little notch out of your right hand.

There were certain drivetrain noises that come as standard equipment on Corvettes. Even though its appearance had changed completely, the noises were the same since the first independent rear suspension and the first 4-speed transmission. There was a muted clunk in the rear end and the transmission made a soft whirring sound in the lower gears: Corvette owners who keep their cars stock accept this as an inherent part of the mechanism.

The earlier Corvette's ride quality would never have described as supple, but with the C3 it was even stiffer. Suspension changes were aimed at better handling and increased understeer but some of the changes (increased front suspension rates and wheels widened to seven inches) had the side effect of a harsher ride. In the effort to increase understeer, the rear roll center was also lowered. Older Sting Rays (Chevrolet started the 1968 year calling its car simply "Corvette," then decided Sting Ray was too good to give up, so changed the name back) were very good handling cars but surprisingly close to neutral steer. If the driver wasn't careful, even with one of the 327 engined Corvettes, and got carried away with the power on tap, they would find themselves sideways in a corner before they knew what happened.

If that was true of the small-engined Corvette, you can imagine what happened when you put the wood to the 427. As the larger engine option became more popular, Chevrolet saw the need to build in a bigger safety factor, hence, more understeer in the '68s. The change was obvious after you gave it a squirt through a few corners. While the primitive Sting Rays were quite happy entering a turn fast and maintaining speed or slightly accelerating through, the '68 Corvette definitely wanted to be powered through a turn, and if you didn't it just pushed through, grinding off its front tires.

Although a different driving technique was required, the C3 Corvette still seemed to get through a corner faster than the previous models, thanks to its lower center of gravity, wider wheels, and a 0.7 inch wider track . The optional power steering was a very high-effort type, and the only indication you had of it helping was that parking effort was the same as normal driving effort. True, it didn't have the road feel of the manual gear but it was not bad either and for those that intended to spend much of their time maneuvering in slow traffic with a 427 perched over the front wheels it was wise to tick the power steering option box.

The C3 also came with power brakes. Unlike the power steering, the brakes were of the low-effort variety and required some getting used to if you had just driven a C2. When it came to stopping the car, however, they were the next best thing to an arresting hook. They could pull the hulking 427 to a stop from 80 mph in 229 feet (.930) and then turn around and do it again and again - this in a era when brake fade was an accepted reality. Unfortunately however the overly sensitive power booster made it almost impossible to avoid lock-up, particularly when stopping from 80 mph. But even so, the"Corvette would still stop within the confines of one lane, straight and true. Four-wheel disc brakes were standard on the Corvette, the only 1968 American car to be so equipped.

While Chevrolet were re-fashioning the outside of the '68 Corvette, they totally re-arranged the inside, too. The instrument panel was done-up in the aircraft tradition with all kinds of matter-of-fact looking instruments on a flat-black background and very little bright metal trim. The speedometer and tachometer were huge and easily readable but it was disappointing that the designers chose to locate all of the small gauges low and in the center of the panel.

Improving on an already decent drive with the C2, the C3 Corvette's seats could reclined and the steering wheel and pedals were almost in the perfect position. Road testers were high in praise of the new interior, claiming the C3 to be an outstandingly comfortable car to drive. The lower roofline and pinched waist resulted in a more intimate-feeling cockpit. The interior width dimension was definitely reduced - making for a much more intimate experience over the original C1 Corvette's "lounge room" feel. The one-piece molded inner door panels were particularly thick at the window sills. In the restyling shuffle the passenger space clearly suffered. The cargo hold behind the seats was good for one fat suitcase. The stylists did away with the glovebox too. Instead there were two cornpartments, one with a locking lid, located in the floor of the luggage compartment behind the seats.

Corvette started the trend to "hide" vital components in '63 with retracting headlights. The C3 improved on this with hidden windshield wipers. The wiper switch was located right in the middle of the instrument panel near the top. Flip the lever to the right and a hatch, the full width of the cowl, lifted with a clunk freeing two captive wiper arms to do their job. And a splendid job they did, too, wiping almost the whole windshield including parts of the glass that were even hidden from the drivers eye by safety padding on the A-pillar and on top of the instrument panel.

But some other innovations didn't quite make the grade. You could forgive the buzzer that went off whenever the door was opened, but a seat belt warning light that had to be manually shut off every time the engine was started, whether or not the belts were fastened, was just plain annoying. Some of the other devices, like the door ajar warning light and the fiber optic light monitor system, were of genuine worth; they gave useful information without annoyance.

Of course the champion of Corvette's trick stuff parade had to be the take-apart roof - if you bought the coupe, it didn't cost anything extra. With the pieces all assembled there were no extra rattles, shakes, or water leaks - just like driving a closed car except for all the latches and cut lines in the headliner. The only real problem was what to do with the pieces after the disassembly operation. Two latches held each panel and, in typical Corvette fashion, panels come out with ease. They were meant to go into the trunk but if you already had anything larger than a small handbag stowed this was no longer an option.

A pair of vinyl envelopes were provided to protect the roof panels while they were being stored. The plan then was to strap the packaged panels to the side walls of the trunk compartment - actually they ended up leaning on the wheel arches and took up a good bit of the available space. The back window clamped to a false roof that dropped down from the top of the trunk compartment. All you had to do was snap the roof back up and that part was out of sight. Driving the open-air coupe was pleasant -with the side windows up there was almost no draft, even at speed.

Some criticism should be leveled at the Corvette's quality. Today's owners are quick to defend the reputation of the car, but today's examples are well sorted. The originals used the cheapest conceivable plastic knobs for the controls, unbound edges of carpet were reportedly visible around the seat tracks and at lap joints behind the seats, and the covering on the seats seldom fitted smoothly. Corvette paint quality had always been poor - so thin in spots you could apparently see the primer underneath. Yet this was the American automobile story. Luxury cars were assembled with the same materials and the same lack of care as compact sedans at half the price.

But these are trifling issues. The C3 Corvette was not a copy of anything, so it did not have to match the quality of say a Porsche 911. Mechanically it was unbreakable and it delivered a performance that its competitors couldn't hope to match at double the price. The handling was impeccable, limited only by street tires, and the Corvette's pitch and float-free ride was ideally suited to high speed touring on American highways. All of these automotive delectations were wrapped up in a package so boldly styled that no one could ignore its existence. The C3 Corvette was a brilliant car with all of the virtues and all of the vices of 1960's American technology. And thats a very good thing.

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Also see:

Corvette Technical Specifications (1953 - 1978)
Chevrolet Heritage
Chevrolet Car Commercials
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