Restored 1970 Chevelle SS454 Convertible With Deceptive LS6 News Asks $500K, but Why?

General Motors wasn’t playing ball with the other Big Two in the horsepower wars in the sixties—at least, not in the muscle car segment, which, ironically, was the creation of the Pontiac Motor Division of GM. While Ford and Chrysler went all in with their big-block hard-punching brawlers and small-block speed machines, and AMC was doing its best to keep up with the corporate ogres, GM was relying heavily on the Corvette to carry the performance flag.

However, there was a problem: the sportscar wasn’t affordable to the masses – and those pesky Mopars and Fords and AMCs were much more wallet-friendly. This becomes crystal clear when we look at the high-power end of the spectrum, where the HEMIs and the Bosses duked it against each other. Then along came 1970, and everything went bust. General Motors was out of the racing game since 1963, going down in style with the Z11 Impala, and it had put a very short leash on its divisions regarding specific power ratings.

As a general edict, all mid-sized GM products were banned from carrying anything above 400 cubic inches. Since muscle cars were intermediates at heart but carried a very potent V8 upfront, the GM interdiction was one of those foot-in-mouth decisions that was the equivalent of firing all the rounds in a six-shooter Colt revolver while bolstered. However, in 1970, competition was tighter than ever. General Motors finally grabbed the adze and extracted the calkins with which its interdiction had been nailed to the mast.

The immediate result was a nice Chevrolet eight-cylinder eruption of torque called LS6. This 454-cubic-inch volcano was more appropriate for railroad and maritime applications than civilian automobiles for personal use. And yet, there it was, a 7.4-liter mastodont shooting out 450 horses and 500 lb-ft of crankshaft-braiding torque (456 PS, 678 Nm). The 426 HEMI was outgunned in every aspect, bar production numbers.

The LS6 engine variant of the 454 V8 was produced in 4,475 copies, spread between the Chevelle body styles: the coupe, the convertible, and the El Camino pickup. How many of each were assembled is a matter for historians and a topic for enthusiast debates. Still, one thing is generally accepted: the ragtop is the rarest of them all. While definitive production records are unavailable, rumors place the total amount between 12 and 25.

While an LS6 Chevrolet Chevelle coupe is a nice treat for any muscle car addict, a drop-top example is nothing short of a holy grail that commends scathing premiums at auctions. While not at the same level as the hemicuda convertible unicorns, the 1970 Chevelle LS6 is no flea market bargain. The high-horse 454 V8 may not be as rare as its high price might suggest, but it wasn’t publicly boasted at the time of its arrival.

The Chevrolet sales literature of the period acknowledged the SS396 and the SS454 engine options for the Super Sport Chevelle, but there was a catch. Despite being equal in displacement, the two versions of the 454 big-block weren’t anywhere near identical. The sales documentation advertised the low-key LS5 motor, good for 360 horses and 500 lb-ft (365 PS, 678 Nm). The LS6, the other hand, wasn’t that easy to come across.

The difference between the two resided in the internals: the brawny LS6 had a massive 11.25:1 compression ratio, rectangle-port heads, 2.19-inch intake valves, and a solid-lifter camshaft with .520 lift and 316 degrees of duration. Seven hundred eighty cubic feet of air flowed through the solitary four-barrel Holley carburetor atop the low-rise intake. Chevrolet even adjusted Muncie's emblematic M22 Rock Crusher gearbox to brave the heaps of torque pumped out from the oversquare big-block.

While essentially a stroked 427, the 454 retained a high-revving tenure thanks to its 4.25-inch bore and 4.00-inch piston travel (107.97 mm x 101.6 mm). The enormous motor redlined at 6,500 rpm—enough to slap the standing quarter out of the Hemi Mopars and the 429 Cobras from FoMoCo. One test from 1970 revealed a 13.44 quarter-mile time at 108 mph (174 kph) with a 4.10 Positive Traction rear and a four-speed manual.

About the gearbox: although it bears the same name, it is not the same product as the Regular Production Option M22. The LS6-paired transmission had finer clutch drive gear splines, larger and heavier main shaft rear splines, a pressed-on speedometer drive gear, and a 10.5 heavy-duty clutch. Small details, but different enough to not be interchangeable with a standard Rock Crusher fur-speed manual tranny.

All in all, the SS454 LS6 Chevelle was around 1,000 bucks costlier than a basic Malibu SS, putting it in the $4,500 price range. And, if the owner wanted to listen to the piston Armageddon sitting right in front of the windshield and ordered a convertible top, the price went up another $200 – right up Corvette alley. Maybe that’s one reason why there weren’t too many built, and perhaps this rarity now commands serious money for one of those few and far-between examples.

Prices in the range of half a million aren’t everyone’s cup of tea, and that’s usually the realm of unrestored originals or cars with racing heritage. However, one restored Chevelle SS454 LS6 convertible with a four-speed is going under the hammer on the 18th of this month, and the estimated selling price is hair-rising.

‘$500,000-$600,000’ is the laconic statement on the auction site for this otherwise impeccable machine, one of the main stars of the Indy 2024 event. The odometer reads 40,264 miles (64,798 km), but a concerning bit of information blows a whistle on this offer: ‘Correct CRV-suffix 454/450 HP V-8 engine.’ Usually, that means ‘not original,’ and suddenly, the half-million seems a bit too much. There’s no further information about the car’s past, and experienced gearheads tend to ask many questions about a vehicle before they reach into their pockets.