10 Muscle Cars That Should NEVER Be Engine Swapped

Congress should pass a law banning engine swaps on these rare classic American muscle cars because it's not a victimless crime

As unthinkable as it seems now, during the gas crisis of the 1970s, people actually swapped out their powerful V-8 engines for slightly more fuel efficient four and six-cylinders. This included badass classic muscle cars, which almost seem like a hate crime. Making this even crazier, gas jumped from 39 cents a gallon in 1973 to 53 cents in 1974. Adjusted for inflation, that's a little over three dollars a gallon in today's prices. Just imagine ruining a 1970 Charger R/T, just save a few pennies.

Another curious phenomenon is the resto-mod craze in which classic rides are completely rebuilt with modern tech and comfort, including brand-new engines. This is fine if the target vehicle is a '69 Camaro that was originally equipped with a 230ci inline-six, but much less so if it's a COPO 427. The weird thing is, many of these resto-mods cost around $300,000 when the same car, faithfully restored, would be less than a third of the price and much more collectible.

When it comes to classic muscle cars, matching numbers matter and the original engine is the major determiner of value. A 318 Mopar is worth significantly less than a 426 Hemi. Then there's the fact that some models are intrinsically linked to their big and powerful factory-installed engines. In the case of some of the most iconic muscle cars ever, an engine swap is a thing that should never happen under any circumstance.

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Dodge conceived the Super Bee package for the Coronet as a less expensive no-frills muscle car alternative to the Coronet R/T. They did come optional with 426 Hemis, which sounds kind of like a frill, but for the most part, they were stripped down and fast-budget rides. Despite the low-end trim, the 1970 Coronet Super Bee with a Hemi is one of the rarest muscle cars in existence.

Engine

426ci Hemi V-8

Engine Output

425 horsepower, 490 pound-feet of torque

Transmission

Four-speed manual

0-60 Time

5.1 seconds

Quarter-mile Time

13.6 seconds

Top Speed

137 mph

According to Hagerty, a grand total of 32 buyers opted for the Hemi in a '70 hardtop Super Bee. That's already rare but when it comes to the Super Bee coupe, only 4 ever got fitted with the 426 Hemi engine. If ever there was an engine that shouldn't be swapped, a one-of-four car is it.

In 1970 GM finally lifted its arbitrary ban on 400 cubic inch and up engines for Chevy vehicles. The most immediate beneficiary of this age of enlightenment was the '70 Chevrolet Chevelle, which came optional with a massive 454 V-8. No longer having to rely on the COPO workaround, Chevy finally had a production car that could rival the Mopar 426s.

Engine

454ci LS6 V-8

Engine Output

450 horsepower, 500 pound-feet of torque

Transmission

Three-speed automatic

0-60 Time

6.0 seconds

Quarter-mile Time

13.8 seconds

Top Speed

130 mph

The 454 SS actually had two available engines, the LS5 and the LS6, which had a beefed-up intake manifold and carburetor that produced considerably more horsepower. The added ponies and torque made the '70 Chevelle SS the king of the streets. 4,475 LS6 Chevelles were produced in 1970, so any that still exist are not to be resto-modded.

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The Ford Torino was always kind of overshadowed by the Mustang, so a lot of people don't realize what a kick-ass muscle car it was. In 1969, Ford introduced the Cobra performance package to compete with bare-bones speedsters like the Plymouth Roadrunner. In doing so, Ford dropped a big honking 428 V-8 under the hood.

Engine

428ci Cobra Jet V-8

Engine Output

335 horsepower, 440 pound-feet of torque

Transmission

Four-speed manual

0-60 Time

6.3 seconds

Quarter-mile Time

14.5 seconds

Top Speed

131 mph

There's a fascinating story about a triple-black '69 Cobra barn find. It was in pretty sad shape, but the owner committed to a 100 percent faithful restoration. It's a great read, but the most important aspect, as it pertains to this list, is that rather than swapping out the battered engine, it was brought back from the dead because a Cobra 428 needs its original engine.

In 1970, the Plymouth Barracuda moved a little closer to being a Dodge Challenger, but it still had its own style. There were three versions available, the base Barracuda, the luxury Grand Coupe, and the high-performance 'Cuda. The latter came optional with all the big block Mopar engines including the 426 Hemi.

Engine

426ci Hemi V-8

Engine Output

425 horsepower, 490 pound-feet of torque

Transmission

Four-speed manual

0-60 Time

5.7 seconds

Quarter-mile Time

14 seconds

Top Speed

117 mph

Since a Hemi 'Cuda sometimes identified its Heminess with bold fender decals and always with a hood badge, that's reason enough to never swap out the engine of one. They are also extremely rare, especially convertibles. Only 14 ragtops with a Hemi were produced in 1970 and of those, only four were equipped with a four-speed. This is what they mean by the term "Holy Grail" muscle car.

American Motors Corporation made some truly great muscle cars in the classic era, but not nearly in the numbers of the Big Three, which makes them rare and collectible. Speaking of rare, how many 1969 AMC Hurst SS AMX 390 do you ever see rolling down the road? Since they only made 52, probably none.

Engine

390ci V-8

Engine Output

400 horsepower, 424 pound-feet of torque

Transmission

Four-speed manual

0-60 Time

4.2 seconds

Quarter-mile Time

12.6 seconds

Top Speed

154 mph

This was one of those homologation models to get the nod from the NHRA, so they only made what they needed to, but they did sell them to the public. As a totally feature-less vehicle, they didn't come with radios, heaters, or sound insulation. The Hurst SS AMX did however come with a big 390 V-8 that was upgraded by Hurst Performance. Obviously, this is an engine that belongs under the hood of the Hurst SS AMX.

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The classic era of muscle cars kicked off in 1965 when John DeLorean had the genius idea of tossing a 400ci V-8 into a Pontiac LeMans. In 1968, the second-gen GTOs got a less-boxy style upgrade, and the Judge became the top performance trim. 1971 was the last year for the GTO Judge, and it was only produced in small numbers.

Engine

455ci V-8

Engine Output

335 horsepower, 480 pound-feet of torque

Transmission

Three-speed manual

0-60 Time

6.1 seconds

Quarter-mile Time

13.4 seconds

Top Speed

125 mph

A '71 came standard with the Mountain Performance package, which meant it had a 455 V-8 under the hood. As amazing as this ride was, only 357 of them sold, 17 of which were convertibles. Either way, it is a rare classic muscle car that should be completely off-limits for an engine swap.

Those "442" numbers on the side of an Oldsmobile Cutlass do not represent what's under the hood, but that's not a green light to swap the engine out. Introduced as a Cutlass performance trim in 1964, it became its own model in 1968. The one consistency is they always came with big V-8s.

Engine

400ci Ram Air V-8

Engine Output

350 horsepower, 440 pound-feet of torque

Transmission

Three-speed automatic

0-60 Time

6.2 seconds

Quarter-mile Time

14.6 seconds

Top Speed

115 mph

The 1969 442 came with an impressive 400ci engine, but the rare W-32 Ram Air V-8 made it a street monster. With upgraded horsepower and stump-pulling torque, the W-32 was the most badass 442 variant ever made. Only 25 W-32s were ever produced, and according to a recent Barret-Jackson auction, there is only one left in existence. That's not just rare, it's an endangered species rare.

In order to homologate their semi-hemi 429ci engine for NASCAR racing, Ford needed to sell it in at least 500 vehicles. Some mad scientists at the company decided they should shoehorn it into a Mustang fastback, and the Boss 429 was born in 1969. It was manufactured for two years with only 1,359 ever rolling off the assembly line.

Engine

429ci Ford 385-series V-8

Engine Output

375 horsepower, 450 pound-feet of torque

Transmission

Four-speed manual

0-60 Time

7.1 seconds

Quarter-mile Time

14.09 seconds

Top Speed

118 mph

It is called a Boss 429 and even lets you know with a 429 Fender decal, which is reason enough to not swap out the engine. Then, of course, it is extremely rare, and putting in a different engine would destroy its value. A near pristine, unrestored, 1969 Boss 429 sold at a Barrett-Jackson auction recently for $605,000, because it was all original, including that 429.

Chevy only built 602 "race-ready" Camaro Z/28s in 1969, which makes it rare enough not to be modded, but the engine is something truly special making it untouchable. Trans-Am series racing rules stated it could have an engine no bigger than 305ci, so engineers put a 283 crank in a 327 small block, creating 302 cubic inches of displacement.

Engine

302ci V-8

Engine Output

290 horsepower, 290 pound-feet of torque

Transmission

Four-speed close-ratio manual

0-60 Time

6.8 seconds

Quarter-mile Time

15.4 seconds

Top Speed

134 mph

This Frankenengine was modestly listed as producing 290 horsepower, but as MotorTrend pointed out, "In reality, the production engines generated more than 375 hp." The vehicle's speed and quickness certainly indicate it packs more punch than advertised. The Z/28 option came with upgraded brakes and suspension, but without the unique engine, it's simply not a Z/28.

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When it comes to Mopars, the first rule is matching numbers or nothing. Mother Mopar is like a religion or cult, so anything that isn't all-original is ex-communicated. To swap the engine out on a collectible Mopar isn't just a sin, it's heresy, and they don't get much rarer than a 1969 Dodge Charger HEMI Daytona, so imagine the collective Mopar freak-out if one were to be modded in any way.

Engine

426ci Hemi V-8

Engine Output

425 horsepower, 490 pound-feet of torque

Transmission

Four-speed manual

0-60 Time

5.2 seconds

Quarter-mile Time

13.7 seconds

Top Speed

137 mph

Dodge created the Daytona and its Plymouth cousin the Superbird to dominate NASCAR, which they did so thoroughly they got banned from racing. Basically, a Charger 500 with a wing and nose cone, a mere 503 were ever built, with only 70 equipped with the 426 Hemi. That matching number 426 is what makes it a nearly-million-dollar car, so the '69 Charger HEMI Daytona is the number one muscle car that should never be a victim of engine swapping.

Brian Anderson's love of cars started at an early age with Hot Wheels, slot-car racing, and building model kits. When he was old enough to drive, he got the fastest thing he could afford, which was 1973 Pontiac LeMans with a 350. After an experimental phase with Toyotas and Nissans, he eventually gravitated to Mopar. He currently has a 383 Magnum and a 5.7 L Hemi sitting in his driveway.