Cadillac Builds an Awesome SOHC V-12 for its 1967 Eldorado...But Scraps It For Production!

Learn more about the Cadillac-designed SOHC V-12 engine that was going to go underhood in the 1967 Eldorado.
Interviews with designer Wayne Kady on the 1967 Eldorado can be found here:
• Coolest Cars: 1967 Cad...
• The 1967-70 Cadillac E...

[@gregpuchalski5951]

I started as an engineer at GM in 1986. One of the first programs I worked on was a heavy duty chassis version of the Cadillac FWD C body vehicle for limousine and armoured car usage. I worked with some older Cadillac engineers who were around when the V12 was under development in the '60s. It was an aluminum block and head design and they said the main reasons it didn't go into production was engine sealabililty, mainly head gaskets, and block porosity issues. They said the 472/500 was done in a compressed time schedule so there was very little "optimization" of the design, rather it was a "home run" approach where they just threw cast iron at it to ensure robustness.

[@ralphl7643]

You'd think after that experience, and the troublesome aluminum Buick V8, they would have gotten those issues worked out by the '82 HT4100, but they still had problems with Northstar head gaskets until 2004. Henry Leland must have spun in his grave.

[@gregrudd6983]

@@ralphl7643 The Aluminum Buick V8 as a Rover engine ended up being OK

[@gregpuchalski5951]

One of the engineers I worked with at the former Buick engineering said one of the issues they had with that aluminum V8 was that leftover shavings from the block that didn't get cleaned out during the manufacturing process would turn into little spheroids when they came into contact with ethylene glycol in the coolant. These would then impinge upon the water pump impeller and create failures. The Brits figured out how to address all the issues and it proved a pretty robust engine design.

[@BuzzLOLOL]

I entered GM engineering via the GMI program in August 1966... saw the '67 Camaro before it came out... quite a surprise design at the time... At 01:34+ in video he's blathering on about a deep groove pulley on the AC compressor... obviously it isn't, as the belt is actually showing partly above the pulley groove... rather than down in the groove... oh well... kids these days... LOL!

[@marko7843]

@@gregrudd6983 I agree. I couldn't believe it at the time, even being a kid, but my best friend's father had a 25-foot Owens cruiser in the brackish Sacramento Delta and it was running an aluminum Olds or Buick 215 - with raw water cooling!

[@NorthernChev]

My 472 Cadillac has been bulletproof over the last 40 years.

[@corgiowner436]

There’s just something magic about a 12 cylinder engine. So smooth.

[@soaringvulture]

Yes, in principle. But those Caddy V-8's were very smooth and silent. The 429 was a magnificent engine that performed flawlessly. I suppose the 472/500 engines were good too but I remember seeing one with its crank in 2 pieces. In any case, there would be no real advantage to a V-12, just like there would be no advantage to having an overhead cam in an engine that tends to run around 2000 RPM. But a V-12 badge would be cool.

[@edwardpate6128]

@@soaringvulture The old 346 L head Cadillac V8's were amazingly smooth as well.

[@soaringvulture]

@@edwardpate6128 Easy for a flathead to be smooth. Not much valve gear to make noise.

[@davidmann4533]

It is the power overlaps that make smoothe running the more cylinders the more overlaps

[@yurimodin7333]

@@soaringvulture v-12 is just 2 v6's stuck together........JMHO but DOHC would have been a game changer even on a 2,000 rpm engine......the sheer amount of valve area is just insane.

[@timbullough3513]

Wow ... over the top OHC V12 and FWD, and leaf springs in the back.

[@roberthoffhines5419]

I know, right? Still....that big smoothie in front...

[@billmagorian490]

Adam I am a fan of your channel. I will have to take exception with you on Cadillac engine reliability. The Northstar V8 and the gasoline engines converted to diesel that were put in Eldorados . So many Cadillac buyers got screwed with these engines.

[@jonnyboy9899]

Cadillac should have had more cars with hidden headlights.....that's such a clean classy look!!

[@billmorrow406]

having owned a 67 eldorado in about 68/69 i can attest that the ride was harsh.. also, while the hidden headlights kept them cleaner thwy were nice until one refused to open at night.. i went on to have a 70 280SL and a 71 eldorado coupe which was a huge car but rode so much better.. i now own a 98k mile 70 eldorado along with my four roadmaster estate wagons, two 59 & 60 convertibles and, yes an 06 SL55.. my 70 eldo is FAST, all original from my former home area in san mateo county california.. while it is not a gas sipper like the roadmasters it is a joy to drive and like the two caddys attracts many compliments while on the road as it is one of the most beautiful attractive cars i have ever had the fortune to own and drive..

[@kevbrown1867]

If I were a betting man I would bet that gorgeous black 67 Eldorado is the favourite out of all of Adams cars

[@Primus54]

Might be his favorite for exterior design, but I’d bet one of his Mercurys or Lincolns are his favorite to drive. As beautiful as the El Dorado is, it most definitely did not have a “Cadillac” ride. Of the platform mates, the Riviera was the superior in ride comfort.

[@laserwizard2]

You have been on a roll lately - amazing history lessons and great episodes!

[@LongIslandMopars]

Regarding the reliability of the 472/500 cubic inch V8s, check out the airboats at Everglades Holiday Park in Fort Lauderdale, FL. They run twin 500 cubic inch Cadillac V8s in their big airboats. One of the captains told me they still use them because they make all their torque down low to turn those big props. When I heard them start up, they still had the classic GM starter motor. It felt like I was back in New York, circa 1970.

[@eddstarr2185]

Maurice Hendry made mention of the Eldorado V12 in his book, Cadillac: The Complete History - but he did not go into as much detail as you have, Adam, in this wonderful video. Cadillac stunned the automotive world when it offered V8, V12 and V16 power plants during the 1930's. Many people in the 1960's became Cadillac customers due to the ongoing image of those magnificent engines. I can still remember the pride of Cadillac engineers when the 500 cid V8 premiered in the 1970 Eldorado. Cadillac tradition! Thank you, Adam.

[@billybcgn25]

I had no idea the Eldo was supposed to have a V-12. It's almost criminal that they flirted with the idea, but didn't bring it to fruition. What an engineering coup that would have been! In 2015 I accompanied a friend to Oshkosh, WI for the annual Experimental Aircraft Association's annual big fly-in (think 500,000+ people visiting, and 10,000 planes at the local airport), and Ford Motor Company had on display an incredibly beautiful show car, paying homage to the original Lincoln Zephyr, painted in the original Zephyr blue. It was gorgeous. Asking the reps, I wondered what kind of power plant Ford would consider using; their answer was disappointing: A turbocharged 4 cylinder. That car would have deserved a V-12 too.

[@michaelbenardo5695]

Yes, Cadillac was indeed experimenting with a V12 and even a V16. Should have put a V12 in the new Front Drive Eldorado. That would have forced Lincoln's hand, and maybe even Chrysler's hand. Ignoring it would have meant extinction.

[@rightlanehog3151]

Adam, That Eldorado certainly had a sufficiently long hood to house a V-12. 🤩

[@christopherkraft1327]

I never knew this!!! Thanks Adam for sharing this fascinating story!!! 👍👍🙂

[@clintonflynn815]

I consider myself well educated on all things automotive, but you really blew my mind with this one!

[@EyesWideOpen61]

This might be your most educational video ever, a lot of golden nuggets in this one thank you Adam

[@danielesbordone1871]

A 7 litre V-12 would have been huge on a car that already had a long hood.

[@mcy1122]

Fascinating video. V8 or v12, the 67-68 ElDorado’s are works of art. Cadillac at its best… Thanks for the great videos Adam!

[@literallyshaking8019]

The 67-68 Eldorado is one of the best looking cars GM ever made, but it would look better if the front wheels were moved forwards 4-6”. That huge front overhang looks off. It would be cool if someone did a complete resto-mod on one, actually swapped in a V12, and took it to a builder like the Ring Brothers to have those front wheels moved forwards (a massive undertaking). They did it with the AMC Javelin they built for Prestone Antifreeze, and it made it look so much better. But then again, that was a cost no issue type of build.

[@johnross6314]

The 1967 V12 SOHC, much of it was based on the Pontiac 6 cylinder SOHC, strapped together in V config.

[@markdc1145]

Congratulations on hitting 💯k subscribers Adam! Well deserved for all the hard work and excellent content you’ve produced over the past few years. I never miss an upload.

[@RareClassicCars]

Much appreciated!

[@jeffreyfelder7981]

I've had Both, 73 sedan Deville, 472 engine, and 70 Eldorado 502 Engine, those engines were extremely reliable...I've had a number of V12 Jaguars..... not so much... but very smooth running engines.

[@marko7843]

The Jag V-12's before the Michael May HE heads were always extremely smooth & quiet - because they were either out of gas or broken down... 😋 (I used to call them 502 as well and I don't know why. I was too young to know about Chevy crate motors, so I wonder if some of the emission stickers went out printed 502?)

[@johneckert1365]

It was a 500, not a 502.

[@e.a.p3174]

my 68 had a 472, it certainly was reliable and powerful, and let's not forget thirsty

[@literallyshaking8019]

I’ve been in that exact Cadillac V12 Phaeton you show at the beginning of this video. It belonged to Jim Taylor’s collection up here in Upstate NY, and was owned by his father (the guy who founded Taylor Made boat products) before undertaking a complete restoration. It was sold at auction last summer, and tragically, when moving it from the auction to its new owner, someone didn’t follow the starting procedure correctly, it backfired, caught fire and almost burned to the ground. Thankfully the new owners are planning on rebuilding /restoring it again.

[@Roddy_Zeh]

I never heard about this V12 before, incredible! Aah, man...I can't believe Caddy scrapped it. It would've been epic to have a more modern V12 Cadillac! (compared to the 1930's, that is)

[@sevinadrew3958]

Excellent discussion Adam! Appreciate your knowledge and experience

[@MarinCipollina]

Thanks for this look back on the potential V-12 considered for Eldorado in its debut. All things considered, hearing the increased cost built in to a front wheel drive arrangement, I would have preferred passing on the front wheel drive aspect in favor of the OHC V-12. I think that would have been a more desirable arrangement.

[@andoletube]

Exactly. It would have been a marketing slam-dunk. Many would have paid a premium for a V12 option - and the V8 would have served for a lower price option as well as spreading the risk with the new V12. History says they backed the wrong horse because FWD was never befitting of a large luxury car.

[@hotpuppy1]

Yes and no. The front wheel drive enabled a flat floor and more interior room. No big transmission hump.@@andoletube

[@NorlandBoxcar]

Very interesting. Did not know that. Since we are on the Eldorado topic, I must attest your 67' is as menacing (in a luxury/sport way) as the Charger you discussed the other day. It really has an epic look to it no doubt. You must be proud to own it. Cheers to that..

[@dougz2855]

My first car was a 1969 Eldorado. Great car. Rare front wheel drive for GM at that time.

[@rovervitesse1985]

Very befitting of the 67 eldorado with its futuristic looks

[@danscott3880]

I watched all the Wayne Kady interviews. Definitely informative

[@matthewpaanotorres7309]

Wow! I never knew this!

[@dznr723]

Mr. Mitchell did have a V12 Ferrari engine installed in one of his special Firebirds. The car still exists at the GM Heritage Museum.

[@j.kevvideoproductions.6463]

Congrat's Adam on rolling up 100 K Subscribers! I remember reading a Collectible Auto Magazine article on the '67 Eldorado and they had a number of styling mock-up photo's of the Eldo that had front end's that were a bit longer than what they ultimately produced (I guess in planning for the V-12 configuration?). It would've been quite a car!

[@milksheihk]

I read an article that the transmission team & the engine team were separate teams & the v12 was cancelled when the transmission team said they would go for a transverse layout, & then changed their mind to longitudinal layout after the v12 was shelved.

[@ricksand6477]

Thank you for illuminating the history on this V12, Adam. I'd read a few scraps of info through the years on this and you are the first to really put this story together! The business case just wasn't there for this engine from a cost and or possibly a reliability perspective. Cadillac mostly had always based their engineering on the tried-and-true, executed extremely well. This "conservative innovation" served them and their bulletproof reputation very well for many decades. Too bad that by the early 1980's when they had to react quickly to multiple fuel shortage scares, they didn't have time to fully develop the V8-6-4, the 4.1 V8 or the Olds diesel they utilized to their usual very high standards. As we have all seen - this and a lot of other factors in the marketplace conspired to cost Cadillac their hard won reputation for excellence. Since those dark times they've built and continue to build vehicles today which compare to the best on the planet, but their reputation continues to lag behind the reality of the quality and capabilities of their vehicles - an argument for another time. Cheers!

[@michaelbenardo5695]

Small rough-riding compacts do not qualify as the "best on the planet".

[@caribman10]

Same lame excuse used when Cadillac shorted the Allante' from the Northstar. Same lame excuse used when Cadillac didn't build the Solitaire. As for "bulletproof reputation", BS. Cadillac once called itself The Standard of the World. Heard that one from them lately? Didn't think so.

[@ricksand6477]

Yeah, it's too bad that it isn't still 1965. Compare what Cadillac produces today with any of their CONTEMPORARY competition, Michael. I love the old stuff, too. But time and tech move on. I've owned a couple of old Caddies and the comfort cannot be matched by the newer stuff - so I hear you! Best, Rick @@michaelbenardo5695

[@ricksand6477]

Yeah, once the 1980's dawned their reputation was destroyed. I was speaking about before then, if you reread my post, which was my point. Cadillac had a sterling engineering record from it's inception in 1903, through the first American production V8 in the teens, the V12 and V16 in the classic era, their flathead V8 which powered many military vehicles in WWII and the first post-war American ohv V8 that along with Oldsmobile, started a headlong rush into V8 performance that still goes on through today. Too bad they didn't have the chops to continue their excellent engineering record when the fuel shortages hit. I also reiterate that what they build today, in 2023, is very well done - if not that stand-out special anymore. @@caribman10

[@ricksand6477]

Speaking of quality and engineering comparisons. 99% of what is built TODAY qualifies as a small rough riding compact compared to what everyone USED to build. Welcome to 2023. @@michaelbenardo5695

[@MrPoppyDuck]

I never knew GM was working on a V12 in the 1960's. Interesting!

[@gregsayles9253]

Adam, I only knew this as my Grandfather had many old Caddy's, & my father, briefly a Ford engineer 😮, told me this!

[@michaelpfaff6009]

Sooooooooooooooooo close to that 100K!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[@ELMS]

100K Subs! Congratulations, Adam! Well deserved. 🎉

[@kurtvanluven9351]

In 1982, I purchased a 1969 Tornado for $20 & a moped. Drove it 2 years and loved it. (The previous owner was an alcoholic, failed to realize it had an exhaust leak. That coupled with the fact the electric windows were frozen caused him to have some unpleasant and dangerous trips).

[@allenminer6244]

Hope you make 100K subscribers soon!

[@HughBarton-yc9uu]

Very nice work. As an elderly Pontiac fan, I feel obliged to point out that, in the 1966 model year, the Pontiac SOHC 6 cylinder was available, in several power ratings, in Template and Firebirds. Believe it sold poorly, and was subsequently discontinued. Several guys I knew had one under the hood of their street race cars, and with proper tweaking it turned out to be pretty strong, and not fragile.

[@TalismanPHX]

CONGRATULATIONS ON 100K SUBSCRIBERS, ADAM!! VERY WELL DESERVED 🎉

[@stoneylonesome4062]

That would’ve been awesome. I’ve always said that the original Toronado should’ve been a compact Grand Touring roadster/coupé, as originally planned, and if they really wanted to make it high-tech, it would’ve been interesting to see it given all-wheel-drive. They could’ve given the Interceptor FF a run for its money. A overhead cam engine would’ve made a great addition to that, as well.

[@michaelbenardo5695]

There was no such thing as "All Wheel Drive", only regular 4 wheel drive, and it would have made the Toronado ride like a truck, and would have made it too tall as well.

[@michaelbenardo5695]

People didn't pay high prices for compacts back then. An expensive car was supposed to be big!

[@67marlins]

​@@michaelbenardo5695agreed.

[@michaelroberts6450]

Later on, Cadillac built a V-16 engine (1990's possibly?) that was dyno tested around 1100 hp if I remember correctly. The engineering lab stuffed it in a suburban for drivability data in secret. I think it made it into one of their concept cars. Just to expensive for production in limited numbers. If anyone knows more about this please tell.

[@richhoule3462]

Congrats on 100K!!

[@robertcushman7002]

this is the first time I've ever heard this rumor. that 429 worked just fine, the 472 in that car was insane 😳

[@johneckert1365]

The 1970 500cid was the BEST

[@damianbowyer2018]

Wow, that is AMAZING Stuff, Adam😊👐

[@aintmanyofusleft]

67 Caddy Eldorado is arguably the most attractive Cadillac of all time. Wish they were rear wheel drive, woulda been super cool with buckets and an automatic console.

[@solemandd67]

My sentiments exactly. It would have been the ultimate, uncompromising, powerful, personal luxury vehicle. I've daydreamed of taking the optional floor shifter from a '68 Toronado and installing it in a bucket seat '67 Eldorado but I'm sure the cost to make it look finished would be astronomical.

[@jonowens460]

​@@solemandd67never knew a console shift /bucket seat option was available for either Toro or Eldorado😮would be Kool to see😂❤

[@paulwindisch1423]

Cadillac V12 rumors began to resurface again in late 2006. I was a tech at a Cadillac dealer at the time. The 3rd gen Escalade had just gone on sale as a 2007 model year. My service manager went to a Detroit area manager meeting and was told GM was developing a V12 for the Escalade to help further differentiate it from its Chevy and GMC cousins. There was speculation that it would be based on the relatively new (at the time) DOHC 3.6L V6 architecture which is a 60 degree V, or possibly it would be a cam-in-block version based on the LS architecture. Then the 2008 housing market crashed, banks froze credit so no one could get car loans, GM and Chrysler filed for bankruptcy, and I never heard about that V12 again. I have no documentation to support this, other than conversations I had with my service manager. In the end, perhaps it didn't matter. Cadillac has never really seemed to have a problem selling Escalades. It has done a nice job filling the role of the floaty-luxo-barges of a bygone era. Still not quite as floaty and numb, but it is otherwise today's version of a Fleetwood Brougham.

[@wilco3588]

For some reason KZbin unsubscribe me from your channel I was wondering why you had gone dark glad you're back haha!

[@franktatom1837]

GM was known for pursuing and then dropping or changing engines. Pontiac started working on their V8 after the war and had it ready to go for 1953, but they were told to hold off because Buick had to have a V8 before the lower brands (Olds, Pontiac and Chevy). Meantime, the Buick V8 was intended to have opposing valves and a hemispherical head, but GM nixed that so late that they had to revise the head design and put both valves on the same side of the head with a tiny intake valve and an odd (if not weird) pushrod arrangement. A giant engine stunted to some extent by a tiny intake valve. Years later, Pontiac developed a small V8 for which they had already cast a large number of blocks but which they had to abandon because it was the same displacement as a Chevrolet under development. The blocks were melted down without any analysis of whether the Pontiac engine might have been a better engine - but I bet it was more expensive!

[@sking2173]

Interesting, especially given that the low-class Oldsmobile OHV V8 was put into production in 1949, four years before Buick’s …

[@franktatom1837]

@@sking2173 Correct, I should not have included Oldsmobile in that comment on V8s. Olds had an OHV V8 in 1949.

[@edwardpate6128]

Don't forget the amazing Pontiac OHC inline 6 with it's novel for the time belt drive.

[@DGillyy]

Reminds me so much of the Mercedes M120 engine except for the MB sfi induction and electronic ignition. Also of the M119 separate distributors on the front of each bank. The M120 was so unique in how it had the long ram intake runners, so the throttle body for the right bank was in the left and the left bank on the right, so you had to be careful about what the trouble codes were telling you. But it had a separate ecm for each bank and you could lose one bank and still have an operable engine. Honest here, we had a couple V12 Mercedes come in with the only complaint being that the check engine light was on and engine lacked power. It was running on one bank! 10:12

[@peterdaniel66]

Thats GM for you .. all talk, no walk.. Standard of the World until it costs money.... lol. GM will never change

[@GoldenGun-Florida]

Buy a Mercedes.

[@rickwitt5735]

I've worked the gist of my career in powertrain and have worked on more canceled or under utilized GM engine projects than I can remember. UV-8, High Output Diesel, S.G.E. (small gas engine, which was retooled from one of the L.G.E. lines in Spring Hill, Tennessee 2015 and never did go into production) are just a few that I can remember.

[@Jimmysidecarr]

Excellent!

[@serfcityherewecome8069]

With their engineering wherewithal, GM would've had about a 98% global market share today instead of being on the brink of extinction if not for all the lethally stupid blunders made by their bean counters over the years ..scrapping revolutionary advances like this one and TONS of other would-be game-changers-- most notably from Pontiac Division during the 1960s-- while approving horrors like the Vega and Olds 350 "Diesel" conversion. 😵‍💫

[@mpetersen6]

GM's bean counters remind me of the geniuses in the British Air Ministry that killed any number of promising projects yet approved some really stupid projects. Brabazon and the Princess flying boat come to mind.

[@rogersmith7396]

Pontiac had an OHC 6 in production. My girlfriend had one in a Firebird. Power glide I think. OHC designs were present in the early days of automobiles. I assume the casting process was difficult back then. If Cadillac was too cheap to get the Eldo suspension right they were sure as hell too cheap for a V 12. They would have had to use it across the line as they did the 472/500. Probably would have made more sense if GM had made a standard 455 for all divisions. Maybe FI in Cadillac.

[@21Piloteer]

The 250 Sprint versions could be had with up to 230 hp!

[@MegaBob12311]

Yeah the Pontiac OHC 6 debuted for the 1966 Tempest with a 230ci L6 later increased to 250ci. It was discontinued after the 1969 model year. It’s a shame they don’t continue to develop it further because a belt driven over head cam L6 or L4 version would have been a much better choice for the smog era that was to follow.

[@MarinCipollina]

Nothing wrong with having the V-12 universal across the Cadillac lineup into De Villes and Fleetwoods and even Calais as well as Eldorados.

[@ralphl7643]

In '77, they sold the Olds 403 in all 3 BOP divisions, but only for 3 years.

[@hotpuppy1]

In the 60 to mid 70's, each divisions was veerry protective of their own engines. Not until the corporate bean counters forced the issue did 'corporate' engines come about and they were a P.I.A. when it came to parts. I worked in parts and a customer would come in asking for a set of plugs for their 350 in their car and you would have to ask for the VIN. They would look at you like you were crazy when you told them their Olds had a Chevy 350 in it or that Firebird had an Old 403.

[@OLDS98]

This was informative and you have really come up with some very interesting videos and information I was not aware of. This was really interesting. Thank you Adam.

[@johntierno546]

Adam, what about the flat 6 air cooled engine that powered the Corvair. That might make an interesting video.

[@raepaul8158]

Thanks , great story !

[@rightlanehog3151]

Let's all CELEBRATE 100,000 SUBSCRIBERS for this fine, upstanding young man's channel!!!! 🥳🥳🤓👏👏👏👏👏🥳🥳🥳🥳🥳

[@davesherman74]

Very interesting! I thought the last of the American V-12s were the post-war Lincoln flathead V-12s from 1946-1948. My dad has a '47 Lincoln coupe with the V-12, and it just purrs along at idle.

[@martinliehs2513]

Thank you for revealing this little known information. While the OHC V-12 concept was an interesting and exotic design exercise, it seems that GM made the right decision to stick with tried and proven reliability of a more conventional engine design. GM was already pushing the envelope on many design fronts in the 1960s, and perhaps the price we paid was much more mundane engineering in the 1970s due to things like Ralph Nader's book "Unsafe at any Speed". I would also agree that packaging a V-12 with a FWD transaxle might have been a challenge in the case of the Eldo.

[@TassieLorenzo]

Wait, why would the cars have still been FWD instead of Cadillac adding an additional range of smaller sports sedans and sportscars as direct V12 Jaguar equivalents alongside the larger Cadillacs, much as Cadillac has today? Was there no appetite for a Cadillac equivalent to the Jaguar XJ12 in the 1970's? (I'm guessing a Cadillac version of the Corvair in the 1960's would have been totally out of the question, as it would have been totally out of character for the Cadillac brand at the time? Attitudes at GM had rather changed by the time the Cimarron, and later Catera, came along as small sporty sedans?)

[@martinliehs2513]

@tassielorenzo7070 the closest American competitor to the Jag would be the Corvette. The first generation T-Bird could have been one as well, but it went off in a different direction and ended up in a similar market segment as the Eldorado. I suppose that, in the eyes of the decision makers, there was no perceived market for a domestic competitor to the XK-12?

[@CJColvin]

​@@TassieLorenzoDon't forget the CTSV as well.

[@solemandd67]

GM passing on a V-12 was a safer decision too because the Achilles Heel of '67 Eldorado's is the braking ability. In its January '67 test drive; "Eldorado Switches From Push To Pull", Motor Trend openly questioned the safety and ethical responsibility of Cadillac for engineering a car with such poor braking ability, comparable to a late 1940's station wagon. Cadillac's response was to hand over a disc brake optioned car to MT test drivers. Even disc brakes were barely adequate. I believe GM was well aware that the Department of Transportation, which had been formed the previous year, may raise power vs safety concerns too, helping them to nix the V-12 idea. Although my '67 had the front disc option, it was still scary to panic stop at highway speeds. Sometimes it's wise to stop while you're ahead.

[@willymccoy3427]

Pontiac put an OHC inline 6 in production in 1965 and installed it into Tempest/Lemans originally and it was an option in Firebirds when they came out in 1967. The OHC 6 came in a base 1 barrel carb and a Sprint version with a Quadrajet 4 barrel.

[@feez357]

Absolutely beautiful video. I have always liked these cars but still settling for what I can afford.

[@jwrappuhn71]

Excellent.

[@johnplovanich9564]

Love your videos.They are so informative. Congratulations on 100k subscribers.

[@gordonborsboom7460]

This engine probably would have been more suited to RWD given the added length The THM 425 chain case takes up the extra room needed for the extra cylinders, it would seem

[@hotpuppy1]

There is a lot of room in front between the engine and the radiator.

[@davidbriggs1649]

I'd like to point out a few benefits of a V-12 that you didn't mention. I don't believe horsepower was a significant factor in going for twelve cylinders, but acceleration would be significantly enhanced over a v-8, one reason Ferrari preferred them. There was also the prestige factor a twelve offered, helping to further set them apart from Lincoln and Imperial. As always, it was nice to get technical information on that little known engine, as well as your perspective on that project.

[@V8_screw_electric_cars]

V12 are also smoother.

[@jeffreyfelder7981]

The idea of the V12 was smoothness, some folks didn't want to know the car was actually running, the Packard was good for those... but the Packard straight 8 was probably just as smooth running as a V12.

[@marko7843]

I would say that Ferrari and Cadillac is comparing apples and watermelons. A large luxury car needs a quiet torque monster at low RPM, not a screaming high-HP, high-RPM motor. They didn't forget about one-upping Lincoln though... I'm pretty sure they came up with 472 just because Lincoln had a 462. 😉

[@marko7843]

@@jeffreyfelder7981 Totally agree about Packard. Even their final V8's were amazingly smooth and quiet. As a kid, I literally walked past a Clipper in the shop one day and was shocked to see the fan turning...

[@BuzzLOLOL]

As to acceleration, disadvantage of a V10, V12, V16 over a V8 is the additional weight... as well as length and complexity...

[@49commander]

That Engine has an Aluminum Block! I wonder if they had Iron Heads because that would have made them troublesome like the Aluminum Buick V-8, Aluminum Chrysler Slant 6 and the Rambler Aluminum 6.

[@michaelmullard4292]

Great video, Adam! And congrats on hitting 100K!

[@rogergoodman8665]

I wonder if part of the reason that Pontiac's O.H.C. straight 6 was the only GM overhead cam engine to make it to production is that before GM jumped full bore into the O.H.C. revolution they wanted to see how customers accepted the 6 cylinder version first...and when it did not turn the world on its ear, GM got cold feet and stuck with O.H.V. designs instead.

[@devonvictor3210]

Agree one of the best looking caddys. Sure wish we had cars this good looking today.

[@manitoba-op4jx]

man you really do know the best cars

[@mcsg_pelecan]

Thank you Adam... A GM OHC V12 should have been built... However...with the Eldo suspension, it probably couldn't handle it!

[@greggc8088]

It took a long long time for GM to figure a way to mass produce a OHC that didn't pour oil all over the place. Glad they finally made it.

[@miceinoz1181]

Yeah, BMW are still trying to figure that one out.

[@Primus54]

GM, among other giant corporations in the late 60s and early 70s, became obsessed with finance-inspired “diversification” as a means to flatten earnings curves. As a result, they no longer had their eye strictly on the automotive business and often had to squeeze out nickels and dimes from their vehicles to pay the freight on their acquisitions. Quality and value began to suffer and the Japanese saw their opportunity to make huge strides in America.

[@23727bgk]

The V12 would have added more weight on the front heavy fwd Eldorado unless it had an aluminum block, an extreme rarity at that time

[@hotpuppy1]

It WAS an aluminum block and heads. One more added cost to manufacture.

[@ferrochinabisleri1587]

I cannot but totally agree.

[@travislostaglia8861]

Hey Adam I sent a Facebook message to you about a 74 LTD I don’t know if you seen it or not. But it was a triple black two door in the Richmond VA area. It looks like a car you would have haha you might already have one I imagine you have a giant garage somewhere with with 50 plus cars in it. Thanks for the entertaining videos

[@Htfsik]

Another missed opportunity by Cadillac. But I can understand why. However, one can dream! Mated to that gorgeous first year Eldorado design? Bring me my smelling salts, Martha!

[@garylangley4502]

I thought that I heard on the video that GM had not made a production OHC engine before this. Pontiac had the OHC 6 engine starting in 1966. My parents had a total of 3 Cadillacs with the 472/500 engine, and they were fantastic. They ran well, and put up with a fair amount of abuse such as overheating. They also had enough torque to move a house. I used the '75 Sedan de Ville to tow a '74 AMC Ambassador station wagon on a dual axle trailer, which I figure is a total of 11,200 pounds for a distance of 100 miles, and it did fine. Plus it got 11 mpg with all of that weight.

[@RareClassicCars]

They had not made an OHC engine before developing the prototypes.

[@Specrotors]

GM still could've made maybe 150~200 of them as a specialty model, to showcase their abilities at engineering...Bill Mitchel was a great one 🙏

[@torqshep4118]

From GMs perspective they probably didn't want to have to carry special parts to support a small production engine. Warehouse space and product support is surprisingly expensive...

[@Specrotors]

@@torqshep4118 yeah I hear ya, still would've been cool to have a few...

[@gustavbabic5004]

Could you imagine the mechanic at the local gas station trying to get the dwell and timing synchronized between those two distributors.

[@djkramit]

Congratulations on 100k. 🎉

[@rogerhinman5427]

Those 1930's Cadillacs were absolutely gorgeous cars.

[@stove7923]

So close to that magical 100 thousand subs. Go Adam!

[@nikmwh]

Thank you for the usual excellent article; it always surprised me that GM in the US stuck with the same technology for so long on the V8’s, I have always thought it would have stood them in better stead when the energy crisis struck in 1972/3 if their engines had been more advanced; in the UK, Vauxhall a GM division, launched overhead cam engines in 1967 (in the Vauxhall Victor), they were excellent units, noted for being smooth, powerful and torquey and were widely exported, that engine was replaced by the ‘Family 1 and 2’ series of overhead cam engines around 1978.

[@scottymoondogjakubin4766]

The v-12 met the same demise as the prototype oldsmoblle DOHC engine the W-43 ! it was a beast of an engine ! sad it never made it to the general public tho !

[@davidmckinney6577]

I love anything Cadillac

[@paulparoma]

Every decent car should have a V12.

[@douglasburket9196]

A minor correction is that GM did make an overhead cam inline six for Pontiac, I believe from 1966 through 1969. The overhead cam six was offered in 230 and 250 cid. So an overhead cam cylinder head for a six (one bank of a V12) was something GM had experience in. I wonder if the Pontiac head was considered for the Cadillac V12? Considering Adam's depth of knowledge about cars of this era, I'm a bit surprised this was omitted.

[@RareClassicCars]

The video talks about the Pontiac 6. The Cadillac V12 was under development before it.

[@Henry_Jones]

Congrats on 100k!

[@theslowride66]

I would love to hear that Twin 6 purr.

[@mpetersen6]

The first OHC engine GM produced was of course the Allison V-1710 V-12. But that was a design they inherited when they bought Allison in tbe 30s. Their first OHC automotive engine to reach production was the Pontiac inline 6. One advantage Pontiac had with that engine was they used the 230 CID Chevrolet inline 6 as the starting point. As stated other GM divisions were looking at OHC designs in the 60s. But imo it was the bean counters who put a stop to most of the ideas.

[@robertmills3682]

Adam, you are spoiling us with all of these daily videos. We are going to have severe withdrawals when you taper back to your standard schedule 😂

[@marko7843]

1. A Tri-Power OHC V8? I sense another video... 😉 2. I didn't realize GM had SUCH a long history of building engines with the wrong v-angle. 3. Cadillac drivetrain engineer: "Let's wait and let Chevrolet try an aluminum block. I hear they're working on something called the Vega..."

[@JackF99]

Another amazing episode thank you Adam! It was especially interesting to hear about Bill Mitchell's pushing for the overhead cam V12 in the Cadillac. Why wouldn't he have pushed it toward the Corvette?

[@RareClassicCars]

Not sure. He did for the Firebird.

[@sprint6855]

You're forgetting the Pontiac OHC 6 that was available in the Tempest/Lemans 1966 to 69, and in the Firebird 67-69. So there was an OHC engine already slated for production in the gm line.