Home » In 1970, You Could Buy A Giant Cadillac Land Yacht With A 500 Cubic Inch V8 And 400 HP: Holy Grails

In 1970, You Could Buy A Giant Cadillac Land Yacht With A 500 Cubic Inch V8 And 400 HP: Holy Grails

400hp Luxobarge Holy Grail Ts2

One of the greatest automotive gifts of the past decade is the democratization of horsepower. We live in a world where a $50,000 pickup truck has 700 horsepower and just about any garden variety EV can produce greater thrust than most people will ever need. Anyone with a decent enough credit rating can throw cash at a family hauler that would leave vintage supercars in their dust. In the 1970s, power was a more grand affair, and engines grew larger and larger to deliver it. In 1970, Cadillac debuted the largest engine it ever lowered into a passenger car. The Eldorado of that year gained a 500 cubic inch V8 rated for an incredible 400 HP and 550 lb-ft torque, turning glorious and luxurious land yachts into stump-pulling power plants.

For many, the mid-1960s through 1970 was the peak of the last muscle car era. In 1964, Pontiac introduced an option package for its Tempest Le Mans. The Gran Turismo Omologato, Italian for Grand Touring Homologated, was a $295 package that dropped a 325 HP 389 cubic inch V8 into a sleek body. The GTO is one of the vehicles that is part of the legend of John DeLorean, and its success helped spark a crazy era of power at General Motors.

Vidframe Min Top
Vidframe Min Bottom

Muscle cars weren’t born in the 1960s, but it was a period when gas was cheap and middle-class Americans could tear up their local streets with an array of high-powered models. Many manufacturers had halo cars with bulky engines and ever-increasing gross power numbers. In 1970, the Pontiac GTO advertised 370 HP from its Ram Air IV 400 cubic inch V8, while the Oldsmobile 4-4-2 punched out its own 370 HP from the mighty 455 cubic inch V8. Don’t forget other greats like the 455 cubic-inch Rocket V8-powered Hurst/Olds with its 390 HP and the Chevrolet Chevelle SS 454 with its 450 HP Chevrolet LS6 big-block V8. That’s just some of what GM had going on. I didn’t mention the bulging muscle produced by Ford, Chrysler, or AMC, but I think you get the point. Muscle cars haven’t died, either. Only now, the power comes from electric motors or forced induction.

1970 Cadillac Eldorado (2)
Streetside Classics

This story takes us right to the end of that muscle car era peak, 1970. It was right before the perfect storm of reduced compression ratios, the onset of emissions regulations, the change to SAE net power ratings, and multiple oil crises that, when put together, turned massive V8 engines into lumps that made less rated power than a basic four-cylinder engine can make today.

But 1970 was right before all of that and Cadillac wasn’t afraid to go big. Cadillac didn’t build its 500 cubic inch V8 to win at the dragstrip but to power its opulent and heavy cruisers that were loaded down with tons of options. After all, Cadillac had to maintain its claim as the builder of the world’s finest cars. The result was the Cadillac Eldorado getting fitted with the largest engine to find itself lowered into an American passenger car. Yes, there have been bigger engines in trucks and sports cars, but the Eldorado wasn’t either of those. Instead, you got stump-pulling power while wrapped in peak 1970 luxury.


The Standard Of The World

Broad Arrow Auctions

For the past couple of decades, Cadillac might be best known for chasing the Germans with its svelte racers in business suits. There’s nothing wrong with that! I’m sure countless readers would do naughty things to get their hands on a Blackwing. There’s also nothing wrong with Cadillac shifting from internal combustion to electric power, though the “-iq” naming scheme can use some work.

Flip your calendars back roughly 70 years and you’ll see a very different Cadillac. The brand didn’t pull luxury car buyers with palatial SUVs with quiet powertrains, but still heavy and land yachts with big, plushy seats, even bigger engines, and hoods long enough to land a Boeing 707 on. These cars weren’t going around the Nürburgring with any alacrity, but they looked at home on Detroit’s Woodward Avenue and in America’s rich postal codes. While Cadillac says “Be Iconic” today, back then, the brand hailed itself as “The Standard Of The World.”


The Cadillac Eldorado, a nameplate that survived 50 years of existence, was one of those vehicles that proved Cadillac wasn’t writing checks it couldn’t cash. It was a vehicle built to celebrate Cadillac’s 50 years of building incredible vehicles and its history is something I’ve touched on before:

As the Automotive Heritage Foundation writes, the story of the Eldorado is rooted in Cadillac’s Golden Anniversary. 1952 marked 50 years of Cadillac excellence and General Motors executives wanted to celebrate with the release of a bombastic new model. Reportedly, the “Eldorado” name comes from an internal naming competition. The winner was merchandising secretary Mary-Ann Marini with the name El Dorado, a reference to the mythical lost city of gold. The name also referred to the subject as being gilded, perfect for a golden anniversary.

As part of Cadillac’s celebration of 50 years, it put show cars on display in venues around the country. One of them was the prototype for the Eldorado, which would enter production for the 1953 model year. The Eldorado wasn’t just a styling exercise for Cadillac to celebrate 50 years on its planet, but a bonafide luxury ride.


1957 Cadillac Eldorado Brougham

The 1957 Eldorado Brougham famously had a stunning design, but enough power features to make a modern car blush. I’m talking about a four-link rear suspension with an industry-first self-leveling air suspension, an early form of a memory driver seat, and so much more. Here, I’ll just fire off some features: The Brougham had automatic power locking, power brakes, power steering, power windows, and a switch to open the trunk from inside of the vehicle. These cars even had vanities in them with metal drink tumblers, a tissue holder, and a cigarette case. You also got your Eldorado with some basic bits to keep your hair looking fine and your lipstick on point. It even had a perfume atomizer. You even got an all-transistor radio and air-conditioning.

This thing was 18 feet long and weighed 5,315 pounds. It was motivated by a 365 cubic inch V8 with two four-barrel carburetors. The 325 HP it made wasn’t for speed and Cadillac made sure the engine under the hood didn’t pierce the expected quiet cabin.

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Paying the $13,074-plus price ($147,000 or more today) for an Eldorado Brougham meant you made it and you meant business. To put that price into perspective, a Cadillac Eldorado Brougham was more expensive than a Rolls-Royce Silver Cloud and buyers were happy to scoop up the exclusive 400 units that were produced that year.

Cadillac never stopped innovating, too. The brand experimented with radar-based collision detection in 1959, automatic climate control in 1964, standard disc brakes in 1968, and a factory alarm system in 1973. That’s just a sliver of Cadillac’s experiments. Some of our readers will remember the infamous Cadillac V-8-6-4 system of the 1980s.

S L1600 (74)
GM via eBay

The Eldorado became a star in its own right as the choice of ride for the rich and famous. Here, I’ll let the Automotive Heritage Foundation show you what I mean:

As the crown jewels of motoring, Cadillac Eldorado Brougham, Biarritz, and other models attracted the rich and famous. Wanting the best that money could buy, Bob Hope, Conrad Hilton, Aristotle Onassis, Mohammed Ali, Richard Burton, Clint Eastwood, Chuck Berry, and John Wayne all owned Eldorados. Frank Sinatra’s 1958 Brougham was Maharani Maroon. Royalty from around the world had to have them, as did movie stars, politicians, mobsters, musicians, corporate executives, public figures, and the fortunately wealthy; everyone wanted to ride in the Standard of the World.

When Elvis Presley spotted a stunning Topaz Gold Firemist Eldorado Coupe parked outside a Memphis dealership he decided on the spot he had to have it, and so he did. A true enthusiast, Elvis is said to have owned 200 Cadillacs during his lifetime (he died at 42 in 1977). He gave away nearly all of them to family and friends.

Over the years Eldorado made numerous film appearances in the U.S. and elsewhere. Movies like Dolomite, Superfly, The Mack, Willie Dynamite, Magnum Force, and Casino all featured the vehicle, sometimes customized to a particular role. The long list of Eldorado TV shows included The Rockford Files, Fantasy Island, Dallas, Seinfeld, Murder, She Wrote, and many more.

Honestly, any vintage surviving Eldorado is probably worthy of being called a grail. Cars like these are just that much of a magical experience. However, for this article, we’re going to look at one variation of the Eldorado.

The Grail

70ca 8

In 1967, the Eldorado went under the knife for a dramatic overhaul. Since the first-generation Eldorado launched for the 1953 model year, the vehicle was a very large front-engine, rear-wheel drive vehicle. New for 1967, the Eldorado retained its girth and 18 feet of length, but its platform became something very different.

Reportedly, the development of what would become the 1967 Eldorado began in the prior decade. Back then, front-wheel-drive wasn’t a common drivetrain layout, but Oldsmobile’s engineers had been experimenting with it since 1957. Reportedly, the development of the Buick Riviera and the Oldsmobile Toronado convinced GM’s Bill Mitchell that Cadillac needed to get in on the expanding market of personal luxury cars.


Image (73)

Cadillac began working on the XP-727 (above), an experimental project to design a sporty personal luxury Cadillac. The design went through a number of iterations, with the original XP-727, the XP-727-2, and the XP-727-3. Reportedly, while it was unclear how interested Cadillac was in front-wheel-drive, the XP-727 was designed with either rear-wheel-drive or front-wheel-drive in mind. Some early examples of Cadillac’s experimental V12 engine were built for a transverse layout. I love the idea of a V12 FWD car from GM.

While it wasn’t known how much Cadillac cared about FWD in the early stages of eighth-generation development, reportedly, Cadillac lost that choice in 1962 when Ed Cole decided that the E-body platform that would underpin the Oldsmobile Toronado would get more mileage with additional GM brands. Development continued with the XP-820 and XP-825 programs, the latter of which previewed something close to what the production vehicle would look like.

Images Cadillac Eldorado 1967 1

When the new Eldorado hit the road in 1967, it borrowed a lot of what made the Oldsmobile Toronado unique. The Caddy borrowed the former car’s front A-arms, longitudinal torsion bars, and anti-roll bar up front, plus the beam axle and leaf springs in the rear. The biggest innovation with the Toronado was its front-wheel-drive layout, achieved with a three-speed Turbo Hydra-Matic mounted longitudinally and driven by a thick chain.


The Cadillac stood out from its platform mates with its own engine and Cadillac touches. It launched with a Cadillac 429 cubic inch V8 rated for 340 HP and 480 lb-ft of torque. The Eldorado achieved a sprint to 60 mph in just over 9 seconds and reached a top speed of 120 mph.

1967 Cadillac Eldorado 20231030
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Reportedly, the Eldorado benefited from the good handling of the E-body platform but offered a better ride than its platform mates. That 429 V8 was a single-year only engine and next came a 472 cubic inch V8 that kicked power to 375 HP and 525 lb-ft of torque. A Cadillac-specific feature included self-leveling suspension.

As Hemmings writes, that 472 cubic inch V8 had its own interesting development history. Many automakers were focused on building engines for muscle cars, but Cadillac wanted a new clean sheet engine to handle the growing need for more and more luxury car accessories. This new engine not only had to drive these accessories but do so quietly while still providing the power Cadillac was known for. Cadillac still called itself “The Standard Of The World,” after all.

472 500 Cid 6

Development of the 472 cubic inch V8 involved more than just making sure you could mount power accessories to the block;  Cadillac also wanted to make sure the engine would keep cool. Efficient cooling jackets, an integral water outlet passage, and even a metal-temperature sensing system that worked as a sort of redundancy for the coolant temperature sensor contributed to cool-running. Engineers also kept future displacement growth in mind, and spec’d five-inch bore spacing.


That brings us to 1970, the final year of the eighth-generation Eldorado. The big news for the year was increased the stroke (4.304 inches versus 4.060 inches) for the 472 V8, creating a 500-cubic-inch V8 monster fed from a Rochester four-barrel carburetor. Output shot up to 400 HP and 550 lb-ft of torque in SAE gross numbers, and while net numbers were not provided, it’s safe to say this was a huge block of power. Not only was Cadillac’s 500-cube V8 the largest passenger car engine on the road at the time, but it was also highly exclusive: You couldn’t get it in anything other than the Eldorado.

1970 Cadillac Eldorado Img 1286
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Here’s how Cadillac described the 1970 Cadillac Fleetwood Eldorado:

Purposefully built to be the world’s finest personal car, the Fleetwood Eldorado is that unique automotive creation: One designed for the motorist who desires unusually spirited performance, individual styling and all the elegance and comfort for which Cadillac is renowned. Eldorado’s exclusive, new 8.2 litre V-8 engine (500 cubic inches of displacement) is by far the largest engine to power a production passenger car and makes the spirit of the seventies come alive with rare excitement. Performing in concert with steady-traction front-wheel drive, precise variable-ratio power steering and Automatic Level Control, Eldorado will captivate you with a kind of driving pleasure unmatched anywhere in the world. Its boldly sculptured beauty gives it a poise and distinction that mark it for greatness. The luxury of its interior appointments tells you that Eldorado is unmistakably Cadillac in every detail. Truly, to drive the 1970 Eldorado is to enjoy a brilliant new dimension in personal motoring.

1970 Cadillac Eldorado (3)
Streetside Classics

According to Hagerty, magazine tests from 1970 revealed that the bigger, badder 500 V8 produced similar drag strip performance as its predecessor. The Eldorado raced to 60 mph in 8.8 seconds and completed the quarter mile in 16.37 seconds at 85.5 mph. Really, the big news here is the mountain of torque from the engine, not how fast the Eldorado could go.

The Eldorado started at $6,903 in 1970 ($56,671 today) but options quickly ramped up your final price. Leather bucket seats were an option, as was a bench seat with an armrest. Other goodies included air conditioning, Cadillac’s new power sunroof, a remote trunk release, a carpet package, AM/FM radio, vinyl roof, power driver seat, power door locks, cruise control, heated front seats, and automatic headlights. Tinted windows were another option.

S L1600 (73)
GM via eBay

Cadillac built 23,842 Eldorados in that year. The Eldorado was redesigned for 1971, entering into its ninth generation. The FWD layout remained, as did the 500 cubic inch V8. However, a lowered compression ratio meant a power reduction with 400 HP dropping to 365 HP, and 550 lb-ft of torque down to 535 lb-ft of twist. In 1972, GM moved to SAE net ratings, which saw the 500 V8 producing 235 HP and 385 lb-ft of torque. Emissions controls arrived in 1975, hobbling the engine to 190 HP and 360 lb-ft. By 1977, the engine was discontinued.


The amazing thing about this engine to me is it still made 360 lb-ft of torque in its final form despite the lower compression ratio, and restrictive emissions equipment – not to mention the move to SAE net numbers instead of more impressive gross figures. So, the engine wasn’t fast, but it made a lot of twist for its application in luxury land yachts. Tuners have also found the 500 cubic inch V8 is receptive to bolt-ons, making it a possible choice for performance applications like drag cars.

1970 Cadillac Eldorado
Streetside Classics

On paper, 23,842 units don’t make for much of a Holy Grail, but who knows how many of those cars have survived 54 years on this planet. The good news is that the collector market hasn’t really gone gaga for these cars. You can find good examples for sale for between $20,000 and $30,000.

As the world adopts more alternative fuel vehicles, it’s fun to look back at how automakers used to make power. Electric motors and turbos do a lot of heavy lifting today, but several decades ago, you got more power simply by making larger and larger engines. The 1970 Cadillac Eldorado is a relic even by today’s standards, but it’s a wild example of the old horsepower wars. Go ahead, hop in your old 1970s coupe and go for a cruise – that’s what these cars were meant for.

Do you know of or own a car, bus, motorcycle, or something else worthy of being called a ‘holy grail’? Send me an email at mercedes@theautopian.com or drop it down in the comments!

(Images: GM, unless otherwise noted.)


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Keith Hunt
Keith Hunt
1 month ago

Everything was automatic. I could sit in the red-leather driver’s seat and make every inch of the car jump, by touching the proper buttons. It was a wonderful machine: Ten grand worth of gimmicks and big-priced Special Effects. The rear-windows leaped up with a touch, like frogs in a dynamite pond. The white canvas top ran up and down like a roller-coaster. The dashboard was full of esoteric lights & dials & meters that I would never understand-but there was no doubt in my mind I was in a superior machine” – Raoul Duke

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