The Most Special Chevrolet Corvette Of The 1970s

The Most Special Chevrolet Corvette Of The 1970s


Important takeaways

  • The 1971 Corvette ZR1 Convertible is the rarest Chevy Corvette from the 70s, with only one in existence.
  • The ZR1 had a unique high-performance block engine and a special handling and acceleration package.
  • Chevy produced just 53 ZR1s from 1970-1972, making it a highly sought-after and valuable collector’s item.


Although stricter emissions standards, fuel shortages, and higher insurance rates were on the way, Chevrolet Corvette Engineers in the 1970s were still putting on performance. That meant the escape of very interesting special projects in very small numbers. We’ve gone through the records to find the rarest Chevrolet Corvettes built in the 1970s.


In order to provide you with the most up-to-date and accurate information possible, the data used to prepare this article was obtained from General Motors, and other authoritative sources, including GM Heritage, CorvSport, and Mecum Auctions.

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1971 Corvette ZR1 Is The Rarest Chevy Corvette From The ’70s


In 1971, the auto industry began following the first production car standards, along with the threat of expensive insurance for powerful performance machines, which effectively ended what many considered the golden age of muscle cars. Despite these challenges, Chevrolet was still determined to provide the best cars for very special customers. Like the one-of-a-kind chevrolet Corvette ZR1 convertible, a race car it’s so rare that we can’t even find pictures of it we can show you.

Chevy still wanted to sell fast Corvettes, even if they were built mostly as secret race cars to help get production parts legal for real race cars that would tear up circuits around the world. Win on Sunday, sell on Monday was still in effect, and a buyer who walked in to see that high-end Corvette might just go home with a more “boring” Vette or an Impala or Malibu for the family.


At the time, big-block Corvettes ruled the road, while Chevrolet offered big creatures like the aluminum-engined 427cubic-inch ZL1 and the similarly sized but steel-block L88. If those weren’t enough, Chevrolet would offer 454 cubic inch LS5 engines that made around 400 hp.

But even in aluminum, big block engines are heavy. Weight is the enemy of performance, especially when it comes to racing cars. So the Corvette team, under the direction of the legendary Zora Arkus-Duntov, the father of the Corvette, created a high-performance model with a small block.

The First Corvette ZR1 Had a Light Block

The 1970-72 Chevrolet Corvette ZR1 featured a 350-inch small-block V8, but it wasn’t like your typical small-block Chevy. This LT1 V8 used aluminum cylinder heads on a steel cylinder block but had high-aluminum intake manifolds and a 780 CFM carburetor instead of the pedestrian Quadrajet carburetors and lower-steel manifolds on standard models. Corvette.


A high 11.0:1 compression ratio and a high-performance 178 camshaft helped maximize the engine’s output. Strictly lifters opened up the valleys more aggressively, with the noise and extra maintenance that went with them seeming fine to the gearheads and racers who were expected to buy the car. The redline was very high for the time, at 6,500 rpm, thanks in part to the light flywheel, making it ideal for track use.

The LT1 engine officially made 370 hp in the Corvette, but NHRA called it 425 because it had more power on the belt. For 1971, a slightly lower compression ratio, required to deal with corporate changes that said all GM cars would have to run on 91 octane unleaded gas, dropped a bit of horsepower, but still made 330 hp and 360 lb-ft of torque. And that’s before the tuners hold it up and make it race-ready.

The ZR1 Comprehensive Package

There was more to the package than the powerful engine because the 350 LT1 engine was available without the rest of the ZR1 package. With this special package, Chevy included a heavy-duty Muncie M22 Rock Crusher transmission. The four-speed transmission got that name because of its ability to handle high torque and for its lack of synchromesh, meaning that grinding gears were common for drivers inexperienced with the ‘box.


The package included heavy-duty power brakes. J56 code brakes include dual piston calipers, large diameter master cylinder, and power assist. It had the F41 Special Use Suspension, which added stiffer shocks with stiffer coil springs in the front and an additional leaf spring in the rear. A thicker front bar was included, and all these features were designed to improve handling.

A high-capacity aluminum radiator with overflow tank, heavy-duty Positraction rear differential, and transistor ignition assist complete the ZR1’s package, but what’s missing from the car is just as important. Features such as electric windows, rear window defroster, air conditioning and radio were all removed or could not be ordered. There wasn’t even a hole in the threshold to attach an antenna to allow you to add a radio later. This car was going fast.


All this performance came at a high cost. The base 1971 Corvette Coupe came with an MSRP of $5,496. The ZR1’s optional “LT1 Special Purpose Engine Package” added $1,010. At around 20 percent of the cost of the base car, this was a value package. It was also unadvertised, which means that very few cars were sold.

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Chevy Built Only Eight Corvette ZR1s For 1971, And Only One Was A Convertible.

Corvette ZR1 Convertible
Mecum

Total Corvette ZR1 production from 1970-1972 was only 53 units. That alone makes it one of the rarest Corvettes ever. 1971 was the lowest production year, when only eight Corvettes were ordered with the ZR1 option. But only one of the eight was a convert. This makes the 1971 Chevrolet Corvette ZR1 convertible the rarest Chevrolet Corvette of the 1970s, and one of the rarest of all time.


1971 Chevrolet Corvette By Numbers

Choice

Model of Production

Coupe

14,680 units

It can be reversed

7,121 units

LS5 454ci/365 hp

5,097 units

LT1 350ci/330 hp

1,949 units

The ZR1 group

7 units

ZR1 Convertible

1 Unit

LS6 454ci/425 hp

188 units

The ZR2 group

10 units

ZR2 Convertible

2 Units

ZQ4 350ci/270 HP

14,547 units

(Source: Corvette Action Center)

Today, these rare cars command a lot of money, but not as much as you might expect. Classic.com shows the last reported sale of a ZR1 from a Mecum auction on May 18, 2024. The car was a 1970 model year and sold for $155,000. Another 1970 ZR1 sold in 2020 for $129,250.


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The 1971 Corvette ZR2 Is Almost As Rare As The ZR1

1971 Chevrolet Corvette ZR2 front 3/4 view

The Corvette ZR2, sold only in 1971, received the same improvements as the ZR1, but with the addition of a rear sway bar and an even meaner engine. The ZR2’s 454 cubic inch LS6 engine made more power, with GM claiming 425 hp and 575 lb-ft of torque. While horsepower numbers and horsepower facts may be all over the place at the time, the real thing probably did more than the official numbers in this case.

Although still rare, 12 were built, making it almost a classic by the standards set by the ZR1 convertible. Like the ZR1, the convertible version was rarer than the hardtop. After all, not many people want a downhill race car. Only two copies of the ultra-fast ZR2 convertible were built, one in green and one painted orange. Both wear hard removable covers now, but only the green one is said to have come from the factory that way.


Chevy 454 V8 LS6 Engine Details

RPO

LS6

Engine

7.4 Liter, Mark IV 454-Cubic-Inch V8

Strong

425 HP @ 5,600 rpm

Torque

500 LB-FT @ 3,600 rpm

Bore/Stroke

4.25 x 4.00 inches

Cylinder Block Material

Cast Iron

Cylinder Heads

Aluminum Alloy

Compression Ratio

9.0:1

Second-Rare 70’s Vette By Numbers

1971 Chevrolet Corvette ZR2 showing off its 454ci big block
Mecum Auctions

The ZR2 is more common than the ZR1, but also more desirable. That has resulted in a higher price for the monster ‘Vette. At $7,672, about a third of the cost of a new home that year, the ZR2 Convertible was expensive when new. Today, hardtop versions of the car have sold for $650,000 and $221,000 in the past year. A big difference, and enough to get the whole house. The two ZR2 convertibles trade hands for more money and with surprising range.


The green ZR2 is on sale soon Mecum’s Monterey auction in 2023 for $863,500. It had sold at an Indianapolis auction house just a year earlier for $962,500. Orange car soon to be sold in 2019 for $368,500, and if resold today it would command a similar price tag for a green car.

Sources: Corvette Action Center, Mecum Auctions, Classic, CorvSport