Rare Rides: The 1970 Chevrolet Chevelle SS454 LS6 Convertible - Street Muscle Rare Rides (2024)

In previous installments of this column, we’ve discussed some fantastically rare and formidable muscle cars that many would consider to be their holy grail vehicle.

Mopar guys would no doubt say they would jump on the1970-’71 Plymouth Hemicuda convertiblesthat I reviewed. Ford freaks would likely point towards my column on the 1967 Shelby GT500 Super Snakeand say I’ll have that one. For fans of Pontiac, their hearts would flutter over my take on the 1971 GTO Judge convertible.

But what about the Chevy diehards? Well, I did have a look at the ultra-rare ’69 Corvette ZL1 in the past, but most would consider that a sports car and not a true muscle car. And yes, I did review the 1969 Camaro COPO ZL1, but to be honest, that is actually a pony car.

So for this month’s edition of Rare Rides, I thought I’d give the Chevy muscle crowd something they could really celebrate. A car that was the pinnacle of pure Bowtie brawn, and for many nonpartisan enthusiasts, the apex predator of all whips from the golden age of muscle.

I’m talking, of course, about the big, bad 1970 Chevrolet Chevelle SS 454 LS6 convertible. So let’s roll up our sleeves and dig in.

The Chevrolet Chevelle had a surprisingly short history before the fabled 1970 model we are concerned with made the scene. In fact, the first model year of the Chevelle was 1964, whereas many of the rides we have reviewed had gestations of twenty or even thirty years.

Chevrolet introduced the Chevelle, whose name was likely a combination of Chevy and gazelle, as a direct competitor to the successful Ford Fairlane. Built on a brand-new platform, the A-body, and featuring body-on-frame construction, the Chevelle was the only fresh American car model released in 1964.

The car was offered as a hardtop coupe, four-door sedan, four-door station wagon, and two-door convertible, while the famous El Camino utility coupe was essentially a spin-off model. All configurations shared a common drivetrain which included 194, 230, 250, 283, and 327 cubic-inch motors, with three- and four-speed manual and two- and three-speed automatic transmissions.

The hot version was given the moniker Malibu Super Sport (SS), and could be had with a four-barrel, 10.5:1 compression ratio version of the 327 cubic-inch V8 which churned out an honest 300 horsepower and 360 lb-ft.

Exterior styling was in line with contemporary standards, consisting of a svelte body full of sharp creases. Horizontal quad lamps flanking a full-width grille dominated the car’s front, while simple stacked taillights were the statement in the rear.

Inside, the car was conservative as well, with standard bench seats,vinyl upholstery, and a comprehensive gauge cluster. Bucket seats and a center console were optional.

Chevy hit it out of the park with the first-gen car, as an astounding 338,286 Chevelles found new owners in its initial year on the market.

Changes to the ’65 were mostly cosmetic and included a revised grille and taillight treatment on the exterior, and slight updates to the dash bezel, door panels, and upholstery on the inside.

In ’66, a major cosmetic refresh was performed on the existing platform. The body was less square and featured the “co*ke bottle” styling that was all the rage at GM in the mid-sixties.

Major styling cues of this treatment included bulging rear fenders, for a more aggressive appearance, a grille that wrapped around the sides of the front fenders, flush-mounted bumpers, and curved side glass. Hardtops received a flying buttress design to the C-pillars.

The interior was completely refreshed too. A new dash with “Jet-Age” styling featured strong horizontal lines to the inlay and gauge cluster. Door panels, seats, and the center console were all new, and interior options included cruise control, tachometer, power seats, and a tissue dispenser.

The Super Sport Chevelle became a model of its own in 1966. Known as the SS396 Chevelle, it unsurprisingly featured Chevy’s venerable 396 cubic-inch big-block V8 and was offered in coupe and convertible forms.

The 396 could be had in a variety of iterations in ’66 SS cars.There was a base 325 horsepower version, a mid-range option that churned out 360 ponies, and the top-of-the-line L78 396 which afforded a rousing 375 horses and a stump-pulling 415 pound-feet of torque.

Checking the SS 396 box on the order form would also add a reinforced frame, recalibrated front shocks, higher front spring rates, and a more robust front sway bar. Non-functional hood-scoops, bright trim, and red-stripe performance tires were also part of the deal.

While the ’67 model closed out the first generation of the Chevelle, Chevy didn’t sit back idly before the total redesign planned for 1968.

Up front, the ’67 was bequeathed yet another new grille and afresh, horizontally split bumper also made a home there. Reverting once again to stacked taillights, Chevy also chose to rework the rear fascia panel that sat between them. Other small trim changes were peppered throughout the exterior and inside. The overall co*ke bottle side styling remained though.

1968 saw a clean sheet of paper redesign that would yield a dramatically different looking car.

The coupes and convertibles now rode on a 3-inch shortened wheelbase at 112″, while the four-door sedans and wagons actually had a 1-inch increase to theirs over the prior models.

The new Chevelle models boasted a distinct body style. All two-door models featured semi-fastback rooflines, with sedans featuring a more pronounced curve at the rear window than in previous years.

The coupes in particular looked much more aggressive. Taut lines abounded with a uniquely sculpted, shark-nosed front end. Quad, horizontally mounted headlights were still the motif, and framed a grill that wrapped around and cut into the leading edge of the fenders. The hood was long and featured twin domes.

The rear quarter windows tapered into a knife-point that jutted into the C-pillars, while the short trunk gently sloped off into a simple, tapered rear end, which featured thin, horizontal taillights connected by a center panel.

The interior was likewise given a complete reboot. Bench seats were still standard, with optional buckets, but they were of a new design. A new padded dash added a bit of flair, and door panels were made of tough vinyl. A full complement of gauges in a upright cluster lent an aviation co*ckpit feel.

Super Sports were once again available in coupe and convertible form, and featured some changes in the drivetrain.

The 396 came in four variations: a base 325hp and the optional L34 350hp engine, both wearing Rochester carbs, two-bolt-main blocks, and 10.25:1 compression. The 375hp RPO L78 engine had a Holley 4150 four-barrel, 11.0:1 compression, mechanical lifters, and an aluminum intake, and the RPO L89, available starting in 1969, added aluminum heads sporting 2.19-inch intake and 1.84-inch exhaust valves.

Interestingly, in 1969, Chevrolet bumped the displacement to 402-cu.in. but kept the 396 moniker for tradition and branding’s sake.

While many would assume that after producing such prodigious stoplight predators for ’68 and ‘69 that Chevrolet would rest on its laurels for a model year or so, this proved to be the furthest thing from the truth. In 1970 they instead upped the ante and created a monster.

Known internally within Chevrolet as RPO Z15, checking off this option box yielded a true contender for king of the streets: an SS Chevelle with 454 cubic-inch, solid lifter V8 that churned out a ridiculously factory underrated 450 horsepower and 500 lb-ft of torque. To the rest of the world, it would be known as the 1970 Chevrolet Chevelle SS454 LS6.

This car had been advocated for by Chevy engineers and executives for a bit. Production of it however had previously been hindered by the infamous General Motors edict, that dated back to the early sixties. It mandating that no car smaller than a full-size could be equipped with a motor larger than 400 cubic inches. Exceptions were made only for the Corvette, COPO, and police fleet vehicles.

In 1970, sparked by the horsepower wars waged against GM by Ford with their 428 Police Interceptor and Boss 429 lumps, and Mopar with its 440 Super Commando and 426 Hemi, General Motors lifted that rule.

The LS6, derived from stroking the 427, featured a hearty bottom end with four-bolt mains, forged steel crankshaft, and forged aluminum connecting rods and pistons.

An aggressive cam with .520 lift and 316 degrees duration and solid lifters joined the party, as did a set of closed-chamber heads with 2.19-inch intake and 1.88-inch exhaust valves. Together, they conspired to yield the engine’s sky-high 11.25:1 compression ratio. On top of the lump sat an aluminum low-rise intake, with a 780-cfm Holley four-barrel.

Either the Muncie M22 “Rock Crusher” close-ratio four-speed manual transmission or the three-speed M40 Turbo Hydra-Matic automatic were available, while a heavy-duty 12-bolt rear was standard with a buyer’s choice of 3.31 or 4.10 gears.

The Z15 package also gave you bright engine accents, F41 heavy-duty suspension, power front disc brakes, SS wheels with F70 x 14 tires on 7-inch rims, dual exhausts with chrome tips, blacked-out grilles, wheel arch moldings, and an SS rear bumper treatment.

Performance of the car was stunning. Just how fast was it? Well, consider that the 1970 Plymouth Hemicuda, considered by many to be a contender for the title of street dominator, could trip the quarter-mile in 13.85 seconds at 107.52 mph, as tested by a period magazine. By contrast, The SS454 LS6 could do the same in 13.12 at 108.17.

As with all 1970 Chevelles, the LS6’s exterior was refreshed, with the angles of the ’68 and ‘69 models squared-off. A completely restyled front fascia was highlighted by body-colored headlight surrounds and twin thin horizontal grilles bisected by a body-color bar. At the rear, the chrome bumper now incorporated rectangular taillights and an insert bestowed with the SS logo. A very popular exterior option was the ZL2 cowl-induction hood which featured a solenoid-operated air intake flap at the rear of the hood that sucked in air to feed that thirsty Holley.

Inside, the LS6 and all SS Chevelles sported a unique instrument cluster with three large round openings. Options included bucket seats, a floor console, and floor shift for automatics.

Chevy’s baddest brawler did not come cheap. On top of an SS base price, an additional $988.55 was needed to upgrade to the Z15. By the time other choice options were added, the SS 454 LS6 Chevelle could cost well over $4,500. Serious money for 1970.

But that wasn’t all you could add. As always, the SS Chevelle was offered in a convertible, and the LS6 was no exception. For an additional $200, one could enjoy the wind through their hair as they crushed the pretenders at the stoplight Grand Prix.

While GM build-out documentation from the era could be called incomplete at best, it is known that 4,475 Chevelles of coupe, convertible, and El Camino configurations left the factory with LS6s.

Because of its very dear price, and the fact that most drag racers opted for coupes to yield better structural rigidity, the convertibles were extremely rare. Most Chevelle authorities place the number of 1970 Chevy Chevelle SS454 LS6 convertibles built somewhere between 19 and 26.

Sadly, because of increasingly stringent EPA standards as well as the gas crisis, 1970 was the sole year for this Bowtie Beast.

It is no surprise then that today, 1970 LS6 ragtop Chevelles routinely cross the auction blocks for stratospheric prices. One example in 2013 sold at the Mecum Auction for an astonishing $1,150,000.

But hey, is that really too much for the meanest Rare Ride of all?