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Hagerty
Hagerty Employee

Displacement unleashed: 1970 brought several flavors of GM 455 | Hagerty Media

In 1970, when General Motors rescinded its edict that limited mid-size cars to 400 cubic inches, it was like uncaging a predator that sat and watched from afar as cross-town rivals offered 7.0-liter behemoths.
https://www.hagerty.com/media/automotive-history/displacement-unleashed-1970-brought-several-flavors...
73 REPLIES 73
hyperv6
Gearhead

These are all great engines and easy to mod. One that gets forgotten is the Cadillac 500. It can be modified and built to run. Just don't go over 4500 RPM.

The lead tech at Edelbrock used to race these and even developed a manifold for these. Drop it in a 80's G body and you have a quick car.
cigarmerchant
Pit Crew

Took my drivers test in my Mom's 500ci El Dorado in 1972. Happy Birthday to her today, she would have been 87.
audiobycarmine
Advanced Driver

Great engines, all.
My Dad had a '67 Buick Electra 225, and, as this article states; she was mighty quick for a heavy car.

It's too bad that a few years later, GM would "homogenize" their engines.
I remember hearing about owners of new Cadillacs being justifyably incensed at finding an Oldsmobile-branded motor under the hood, (as if a new Cadillac owner would even deign to open the hood...)
mrhws
Pit Crew

Yeah, I remember the law suits on the GM motors. I think it started with Olds using Chevy motors and people sued saying if they wanted a Chevy they would have bought a Chevy.
mbr2000
Intermediate Driver

A friend had a late 60s Olds Cutlass base model with a Chevy straight 6. As I recall, he was part of a class action law suit against GM by folks who thought their upscale GM cars should have better than entry level Chevy engines. I don't remember how that turned out though. A couple decades later, full-size Buicks could be found with a Chevy 5.7 liter roller cam engine under the hood.
drjim
Detailer

My Dad had a '69 Olds Delmont 88 that the dealer ordered with the wrong engine. Instead of the 455 2-bbl he wanted, he wound up with the 455 4-bbl/390HP, which required some optional equipment he wouldn't have ordered. He finally reach a deal over the price increase and bought the car.

Yow, was it quick!

I had a '69 Charger R/T at the time, and followed him up to the dealer once for a service appointment. I could barely keep up with Dad, and he kept pulling away from me. I had a ball borrowing "Dad's car", as it was quick enough to embarrass most pony cars, and quite a few muscle cars. By the time they realized you were "racing" them, they'd lost several car lengths, and the big Olds was really pouring it on by then.

- Jim
mbr2000
Intermediate Driver

Even a 64 Olds with a 394 wasn't too shabby, Guys with Chevelles and Impalas could get there butts stomped unless their Chevys had hi-po 327s and proper gearing. What was really cool back then is you could specify an axle ratio on most US cars. Check the 3.91 box, and that heavy Olds with 394 cubes would destroy a 327 Chevy with a 3.08. But just don't take the car on long highway cruises!
Tinkerah
Technician

I've lost track of all the opponents I've beaten who didn't even know I was racing them....Sorry Doc, you walked into that one.....
mwmyers91
Detailer

The Buick had 2 advantages, 1. the tourqe, and 2. the weight. But all in all these motors were monsters.
F360Spider
Detailer

I had a Buick Gran Sport 455 as a teenager to drive around. It was a very difficult car to drive, especially in snow. The front end was so heavy that the rear wheels would spin at idle. I got pretty good at driving it after a few months but really, it was a terrible car with awful handling characteristics. Of all the cars I've ever owned, the Buick was the absolute worst. It was fast though. I nearly killed myself many times in the car and wonder why I am here today.
knucklebusted
Intermediate Driver

I have to disagree. The Buick 455 is THE lightest of all GM big blocks. It is only 25lbs heavier than a small block Chevy, thanks to the non-skirted block and high nickel content that allowed thin-wall casting. I drove a Buick GS Stage 1 (455) in the early 80s winters and with snow tires and a posi, it did just fine. The big block Buick handled better than the similar big block Chevelle due to the Chevy's much heavier front end.
NickB
Pit Crew

Very true. But the lightness of the Buick was reflected in the weak bottom end. They wouldn't take much of a pounding.
BMD4800
Instructor

Oil pump gears ate the aluminum timing cover and allowed the mains to get starved.
Padgett
Intermediate Driver

Interesting, those same characteristics made it a great Autocross car. With a Muncie and posi you could just plant the nose on a pylon and walk the rear end right around. Guess it took a squirrel.
BMD4800
Instructor

Must have been different where you were.

I learned to drive on and drove a legit dynoed 425hp/500 lbs ft A-body in the upper Midwest snow from age 16-20.
I also drove an ElCamino in the same area, but mostly the a-body. Those cars, in my opinion, were infinitely more predictable in snow than the GM-10 garbage pile, or really nose-heavy front-drive LeSabre.
During my drivers test I had to transition from a plowed, paved Main Street on to an un-plowed side street with a decent amount of snow at the transition. I just burped the throttle and gently brought the tail around with a little correction. Never left my lane, never even hung the tail out. Tester asked how I learned to do that. I said “I built this car, I know it better than my siblings.” Only missed 2 pts on the test because the guy didn’t believe the car came stock without a right mirror.
harleylu
New Driver

I had a 1969 427 390hp in 1971. How does this engine compare to the 455?

Padgett
Intermediate Driver

Doesn't, the 390 tripower was several "stages" down. TOL for civilians was the 435hp tripower. The L88 was rated at 430 hp so normal people would not buy it. Chevvie did the same thing with the Z-28 rating it at 290 hp and the SS-350 at 295.
petersalt
Intermediate Driver

Pretty well, actually. The 455s in A-bodies would tie or even win in the stoplight to stoplight race (or maybe the 1/8th mile drag).. the 396/400/402/427/454 in B-bodies [or Ford 406/427/428/429s in equivalent mid-size bodies] with HP cams and better high RPM breathing would win the 1/4 mile drag ... until the A-bodies MIGHT catch up on top speed with all their torque (but they MIGHT also run out of gas first).
MustangJim
Detailer

Great article, thank you for always bringing us these informative bits. Having grown up in the era and being a backyard mechanic on my pet projects I often forget the details.
Having owned a goat in the early 70,s I was immediately going to say Pontiac. My alegence went back to ford soon after so i didnt always know details on individulal gm cars. But I forgot about those w 30,s! They deserve #1 spot on the 455,s I think. Now, my question that I know one of my car piers will be happy to answer. Did the big cam w30 have solid lifters or was it hydraulic?
majorbob
Pit Crew

I purchased my first Olds Cutlass in 1969, a Cutlass S with a 350 CID. Soon after I got shipped out to Vietnam and left the car for my girlfriend, now my wife, to drive. I was gone for 2 years and she managed to wreck it, though it was not her fault. The car was totaled. I came home in 71, we got married and I decided I need a new 442, which I had always wanted. In September of 71 I ordered my beautiful 72 Olds 442 W30. Today it is setting in my shop as beautiful as it was when I received it in February of 72. There are lots of memories associated with my Olds, most of them good. That 455 rocket did get me in trouble a few times but it saved my butt on several serious occasions. I am very partial to the Olds 442 and the Rocket 455 W machine. There are lots of interesting stories around my Olds and myself. It is definitely a keeper.
mrhws
Pit Crew

Thanks for your service. I was in Vietnam in '70, first with the 199th in Bien Hoa and then with the 101st in Hue. Got out on a Christmas drop in Dec 70.
majorbob
Pit Crew

Thank you brother. Semper Fie. 

Spyder
New Driver

Interesting story. My parents owned a 1969 Oldsmobile Delta 88 with the 455 - 2bbl carb ( HP ?). By 1973 I was old enough to drive. I was allowed to take the car on dates. Of course I had to be back by 11PM which meant that I would drop my date off on the other end of town and I would "fly" back home. I never got stopped in that car. I graduated from HS and was allowed to buy my own car. I found a 1969 SS Camaro - Hugger Orange, with 396 - 350HP. This car came from the factory with expansion chambers - no mufflers. I only paid $1150 for the car. Oh how I wish I had that car now. But I only had it for 3 months. Later, since we are talking about 455 CID engines, in 1977 I purchased, for $3000, a 1973 Pontiac Trans AM with 455 CID and Shaker scoop. The scoop came with a cover on the scoop - i.e non functional, but the person I bought the car from had removed the plate. This was a nice car - 300 HP, but it was not the Super Duty. It was my understanding that the Super Duty was a rare engine in the TransAm. I understand the the SD had solid lifters which meant, as I understand, that the valves needed to be adjusted often. I wish I had that car too, but who knew back then that the cars would be worth a lot today.
NickB
Pit Crew

The Chevy 454 belongs in this article as it was part of the same corporate movement. We had the detuned version, a 1974 Caprice, which was virtually identical to a 350 in terms of performance, that is, in "normal" driving. Then one day while in a hurry, I hustled it up to 100mph. After that it kept going. And going. Honestly don't know what that car was capable of. The speedometer only read to 120.
Diego
Detailer

If Chevrolet built a 455, maybe it would have appeared in the article....
Chevelle_man
Intermediate Driver

One-ups-man-ship at its finest. IMHO...including the "smaller" Chevrolet LS5 and LS6 big blocks would have made this a more interesting article since NONE of these other GM motors comes close to the LS6 in both horsepower AND torque. I guess maybe there is a replacement for displacement.
Hopper12
New Driver

Well, not exactly correct that none of the other GM motors come close to the LS6 (great motor btw, and I have a vette with an L71). Hot Rod magazine at the time took 3 new cars and put them on the dyno. Here is what they found (advertised/dyno shown): 426 Hemi: hp: 425/460; tq: 490/500. LS6: hp: 450/450; tq: 500/505. Olds W-30: hp: 370/440; tq: 510/510. Great engines for their time.
Diego
Detailer

The reason why Chevrolet wasn't included in this article is because the brand didn't offer a 455. 

I wonder how much more torque did the 454 offer compared to the cars in this story? The answer is not "the others didn't come close." 

68GSS440
Pit Crew

i know you wrote the article based on "advertised" displacement BUT the actual displacements all varied as much as the bore and stroke...
Chevy 454 actual CID = 453.96
Buick 455 actual CID = 455.83
Olds 455 actual CID = 454.38
Pontiac 455 actual CID = 456.01
so for arguments sake aka discussion, maybe it should've/could've been included.
but as always, you wrote a GREAT article, THANK YOU.
KenJ
Diego
Detailer

@68GSS440, Word count didn't allow it. 🙂
mrhws
Pit Crew

I had planned on ordering a '71 GS 455 thru the military while in Vietnam and have it sitting at Ft Lewis when I returned to the states in January '71. I have previously owned a '65 Gran Sport with the 401 nail head and 4 speed, so I knew the Buick power potential. Had to cancel my plans when my dad notified me I couldn't get insurance on the GS or the '68 Charger R/T I currently owned. My dad was driving it and making payments. Something about young males and performance cars over 350 cubes. Ended up getting a '71 Duster 340 and dad kept the Charger until. '74.
jaysalserVW
Detailer

We owned an original 1969 Delta Oldsmobile, Hard-top Convertible with the 455 Engine, with a small carburetor. Despite the large engine, the car could average 17-18 mpg--street and highway driving. The car was original, still had the Owner's Glovebox Edition Manual. It had a white vinyl top and was painted a metalic light green. The car was long and took lots of space in the driveway in our older place in town. It would NOT fit into the older garage. The stereo was factory--to kill for. We sold it so that we could, instead, park two smaller cars in its footprint. I do not miss it!
mbr2000
Intermediate Driver

Your fuel mileage comment made me think about a friend's late 60s (67-68, I think) Buick Electra 225.  With five of us and our luggage, that car made the trip from the Treasure Island Naval Base near San Francisco to the Dallas/Fort Worth area averaging 19 mpg!  He had been bragging about his mileage, but none of us believed him until the first couple fill-ups on the trip.  I can't remember the engine size, but the car must have had some very tall gearing.  

bobbieduvall
New Driver

Great article, but why do you people keep torturing me? What did i ever do to you guys? I cried through the whole article. I all read was HP this, HP that, high compression, high torque. I have a 74 Pontiac Grand Ville Convertible. I love my summer drive. It's all original, big, roomy, lots of stares and it moves...slowly. It has a 455 4bbl. No HP. My mechanic said these cars were rated using DP, Donkey Power.
I lost a race to some kid on a hoverboard.
lol
TomPettylives
Pit Crew

Carry that 70’s boat torch with pride brother. It’s sound nice, speed isn’t everything, especially at the drive-in! Catch a classic double feature of Peter Fonda like Dirty Mary Crazy Larry and Race with the Devil at the drive in and make out with your date at intermission! Then ask who jelly?
mbr2000
Intermediate Driver

It may have a 2.41 or 2.56 rear axle and/or single exhaust with highly restrictive muffler.  Might also want to check ignition timing advance and carburetor operation.

petersalt
Intermediate Driver

You can make it a 455 SD with some rebuild parts.
Find yourself an 'old-guy' mechanic who remembers
how to hot-rod. Change the rearend to a 'drags' ring
& pinion .. then put a 'built' 700R4 transmission to fix
the gas mileage back to acceptable. It won't be 'stone
stock' anymore, but it WILL jump like a scalded cat.
Padgett
Intermediate Driver

Always thought the oversquare Buick was the best of the bunch particularly in stage 2 (OTC) form. My 4-speed 70 GS beat A Lot of Z-28s in autocrosses.

Pontiac OTOH was stuck. Unlike the others, Pontiac never had a "Big Block" so had to make do with what started out as a 265 cid V8. (I think of them as small and large journal). They could not bore much further than the 428 (455 bore is a .030 over 428) so had to add stroke. Unfortunately the first big car 455s had a two bolt crank and a weak bottom end. So many were warrantied that when the vastly improved and reliable '71s came out, few were interested. Motorheads still wanted a Ram V.

1973 and the Super Duties is a whole 'nother story and one of politics rather than technology. Originally the SD engine was supposed to be available in F, A, and G bodies - is mentioned in the early Grand Prix catalog and several Grand Am "mules" were built.

And then the EPA found out the games Pontiac was playing with emissions devices, an order was issued and changes were mandated as of 15 March, 1973. Compliance resulted in cancelling of the SD option for A and G bodies and derating of the F body SD from 315 to 290 hp.

Bottom line: what really went on is far more interesting than statistics.
blur911
New Driver

One thing not mentioned is that the Olds 455 found it's way into a GMC....a motorhome at that. From 1973-1976 the Olds 455 mated to the same TH425 as the Toronado powered the GMC designed and built motorhome, the last two years of production has the 403 Olds.
It had a few parts particular to the motorhome, such as carb and intake. Most of these old beasties are still on the road. I have a 1976 I'm working on getting on the road again, so far the drivetrain seems to work perfectly.

Now, does Hagerty insure classic motorhomes?
rockable
New Driver

I've just finished building a BB Buick 455 for my 49 Buick Super Sedanette. Unfortuately, I can't post pictures but it turned out great. I think that torque monster will be wonderful in that big old land yacht.
eighthtry
Intermediate Driver

I still have a 74 455 Cutlass Salon. While that engine could run well, it was only good for 200 miles on the highway before stopping for, thank goodness, a tank of regular gas. About 10 mpg. Had to plan when going across the desert in those days.
BMD4800
Instructor

Not the biggest fan of the big-main bearing journal 455s, but they were each really great in their own right.
I’ve had both an Olds and a Buick 455, liked each.
With the Olds - cylinder heads, intake manifold, and top-end oiling are problems.
With the Buick - main oiling.
The small-bore Olds was my favorite steady-state highway engine. Even with 3.42 gears, it cruised perfectly and got a relatively thrifty 17mpg with a flipped air cleaner lid, carb tune, timing curve adjustment, and good dual exhaust out the factory dual manifolds.
The Buick? It was a beast. The more I beat on that thing, the better it ran. Same tuning tricks made it a freaking monster. It’s like Buick intentionally held it WAY back. Not as fuel efficient, but it revd better than the Olds and was generally more fun. That was in a bigger car, so performance and mileage comparisons aren’t valid, but with more weight and 2.93 gears, it still felt quicker and again - was way more fun.
Pontiacs…a totally different world.

But then to compare against a Stage 1 or Stage 2 455 is a totally different game as well.

An LS6 and a legit Stage 2 are pretty well matched. A stage 1 may be a little down, but it did have more torque than the 454 and a little less weight.

Sorry to the Cad 500 fans, but they really aren’t performance motors or set up to be them. They just have displacement. Low revs, poor valve train geometry, no really decent heads that are readily available, even the Edelbrock intake is just okay. They are neat, different, but why spend the money on one for “performance” when you can make way more power with a set of Chinese cast big valve vortecs and a decent roller cam in a 383 stroker?

This from a nailhead guy, so if you’re going for nostalgia or uniqueness, that’s understandable.
BMD4800
Instructor

Nothing worse than a beautiful GM engine bay marred by an Accel supercoil.
If one wants to make their machine run worse, just set the initial timing to TDC. All the garbage performance without the top-end misfire.
Porsche911914
Pit Crew

I still own my mom's extremely original 1970 GS455 convertible, every drive I tend to light the tires up, tons of torque. Got my driver's license and first ticket in this car.
bboomer147
New Driver

Don't forget Caddy's 500 cu.in. , 400 hp.
Diego
Detailer

But it's not a 455.
travelingtim
New Driver

I just picked up a 1972 Buick Centurion Conv. with the 455. It was a courtesy car for the 1971 Rose Parade. Its completely stock (and a bit rusty). What are some quick and easy mods I can do to give it a bit more quick punch of the line? Dam it's a boat!
BMD4800
Instructor

before you do anything, get an oil pressure gauge and make sure the pump isn’t worn out/low oil pressure.  If so, replace the cover and pump.  

after that…


Block the exhaust gas cross over, rebuild and tune the Q-jet, recurve the distributor and set the initial with way more timing.

How much depends on your location, elevation, temps, and fuel.   Duals, 2.5” mufflers, tails can be 2.25 with little loss.  
The old school b1b intake is good, unless you want to keep the intake stock.  72 ditch the points.  

beyond that…in a heavy B-body, you need some 3.42s for the 9-3/8.  

VC455
New Driver

Great article. Diego always has interesting takes on the classic era of muscle cars.

One point could use explanation. "the all-new 1970 Firebird—introduced mid-year due to a strike..."

There was no significant strike during the 1970 model year. The long strike in 1970 affected 1971 model year production. The Camaro and Firebird had an all-new design for 1970 and they were affected by continual delays for some unspecified reason. The 1970 Corvette was just a refresh but it was delayed so it could be introduced along with the Camaro and Firebird.