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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In 1970, when General Motors rescinded its edict that limited mid-size cars to 400 cubic inches, it was like uncaging a predator that sat and watched from afar as cross-town rivals offered 7.0-liter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.
Advanced Driver

@VC455, Thank you!
New Driver

Owned a 1977 GMC Eleganza II Motorhome which was on an Eldorado platform with 455 V-8 and FWD. Needed that extra HP to push that monster! Great combination though - put over 100,000 miles on it with no major engine work required!!
Pit Crew

I am revving a 70 Riv
Pit Crew

George Hurst knew what he was doing. He had first approached Pontiac as early at 1967 but was declined. Pontiac suggested he try Olds, the rest is history! 
Gotta ask, would there have ever been a W-30 without the success of the ‘68 and 1969 Hurst Olds 455?

Pit Crew

First W30 was in 1966.

Pit Crew

That is true but not with the 455 which is point the article and my reply. Not to mention that the hp and tq in the ‘66 &’67 didn’t come close to the ‘68 to ‘71 455 and other later model V8s until the decline from government regulations demanded cleaner emissions thus killing the muscle car until recently. My point about George Hurst was that he helped make mid-size cars with higher cubic inch engines ready available to the market. Yes, Chevy had COPO and individual dealer optioned engine swaps but that was not readily known by the average public or if it was, not affordable. For less than $700, you got a increased cubic inch engine not available any other way, a huge forced cold air intake scoop, working Rear deck foil, Hurst race designed shifter with proven shifting improvements, special exterior two tone paint and hand pinstriping. You had to pay multiple times that for a specially ordered COPO, Yenko, Baldwin-Motion, Nicky or Berger car just for a engine size increase. Hurst was first to bring racing inspired credibility to the masses at a reasonable price. And his success bred improvements within the Industry straight from the manufacture in the final days of the muscle car craze, IMO! 

Pit Crew





 My rotisserie restored

1969 Hurst Olds 455 Convertible tribute with date coded ‘69 455 with Hurst ground cam and “D” heads and Posi-track with Dual gate shifter. Drop the top and cruise or leave it up with factory original Air, tilt wheel and power bucket seat.



You should get some photos of Linda Vaughn with your car.
Pit Crew

Her signature is on the shifter console. 


TomPettylives I beg of you, teach us how to post photos!
Pit Crew

First, you must be a registered member and must be signed in as a member then open the article .

At first I couldn’t post photos at first when reading the article. But after leaving the email article and signing in to the Hagerty site, I went back the the original story and clicked on the reply button under the articles last button as in this photo,





 I got the reply box with a mountain photo icon and I clicked on it to attach to my second reply. 

New Driver

All great, but I'll take the Buick. The oiling system is poorly designed, but can be remedied. Other than that it is the torque monster of the three.
Pit Crew

Sadly I must agree. Biggest bone headed decision I made was selling my 1970 GSX Stage 1 in Yellow. The torque it had would tear the paint off my Hurst Olds 455. 

Pit Crew

I’ve owned a 1970 Buick GS455 for less than a year and am blown away by how fast it is. There’s also alot of after market performance parts that can make it into a meaner monster.

Just what do all these HP ratings really mean? I believe it was in 1972 that the protocol for SAE HP ratings were changed. Identical engines from 1970 and 1972 had different HP ratings due to the change in how it was determined. Same engine, same output, different numbers. Do any of these articles take this into account? If not, how can anyone really compare the HP? Any pre 1972 SAE rating can not, in the least, be compared to a 1972 and on SAE rating. In the early 60s my car was rated at 88 HP SAE by the factory. The same engine is now rated at 74 SAE HP because of the different SAE protocol. Nothing changed in the engine.
Advanced Driver

About the same time TQ and HP ratings went from Gross to Net, compression ratios also dropped.   Therefore the later model engines would have had somewhat less actual power, especially the high performance engines that needed high static compression to compensate for very late intake valve closing angles.  That's assuming the camshafts stayed the same.


As far as Pontiac went the 455 was designed to be a torque motor to move the heavy cars in their line up, and it worked well. The torque band was good from 1500 to 5200 rpm and that`s where most street cars of the day lived in that range. Camshaft spec`s came into play more for low revving torque motors like the 455 but it suffered due to the long stroke 4.21 and large journal crankshafts at 3-1/4 diameter equals more reciprocating mass weight limiting rpm and less top end horsepower capability, in other words the 455 ran out of steam at 5000 rpm and peak torque at that point was already past it`s high point. This is why the 400 was a better choice and would produce more horsepower at top end with close torque numbers to the 455. The 400 with its 4.120 (4.150 at 0.30 over same bore as a 455 ) bore and "3.75" stroke was a better combination for making power in it`s rpm range for street cars especially lighter one`s and responded better to performance upgrades such as a hotter cam, headers, etc. and the round port mid 1968 ram air 2 heads. Ram air 2 , ram air 3, and ram air 4`s, were all 400`s . Bottom line........given equal torque in both engines, top end horsepower win`s races.
New Driver

When all of this was going on, I was finishing high school in 1970, but reading the major car magazines of the time (CL, MT, HRM, CC, etc.). I noticed that in some of the road tests, a deeper rear axle seemed to be the key to performance, more than engine size. I was and am more in the Mopar orientation, so all of the GM and Ford competitors were always interesting to me.

The GM intermediates were all different aimed at different customer demogrqaphics, which determines their engine choices and equipment. To me, the only "real" competitors were Olds and Pontiac, no matter what the torque ratings might be (as they were all close). Of those two, Olds would have been my choice back then.

One issue which seemed to always afflict Pontiacs was their cyl head flow, even on the 389s. Which resulted in longer duration and shorter lift camshafts. There was a reason for that combination. Buick seemed to have some similar issues with their 401s, too.

Back then, many engineering ideas were "by sight" rather than in hard evidence, it seems. Which resulted in the round port Pontiac Ram Air cyl head series. Big valves, big round ports (just like the cutting-edge race engines of the time) just had to flow more and make more power. Yet when flow benches came into the picture (as reported in a Pontiac enthusiast magazine of the 1980s), the RA IV heads were not much better than the prior RA III heads in port flow. Seems that almost all of the SD motors had to have 4.33 gears to run with the others?

Being a long-rod motor from the start in 1955, Pontiac was on the right track for a smooth running and marginally more powerful engine than the similar Chevy motors. Reciprocating weight of such? Compare them to the Ford FE motors with their large crankshaft counterweigfhts and LONG nose cranks. Or Chrysler's 1k gram B/RB engine piston weights. Sorry, I never did consider a Pontiac motor as a serious horsepower contender, although many considered it such.

Olds had the performance reputation to uphold, which they did pretty well. With classy cars, too!

Buick was the dark horse in the bunch. Plenty of off-idle torque and power that went into the 5000rpm band. Just gear it to use that power and NOT expect it to last if regularly taken to 6000+ rpm very much, as I understand it. In a car that was a very nice place to be.

YET . . . there are TWO other stories in the full consideration of getting the powre to the pavement, in stock form. ONE is the undercar exhaust system sizing. The OTHER one is the spring/'shock/sway bar specs. MANY differences in these items for vehicles that were so similar! EACH approach tended to reflect their desired customer demographic and their brand orientations. AND then there were brake linings used with the GM-spec 9.5" rear drum brakes! Engines, drag race results, and styling are only A PART of the total story.

Good article,
Advanced Driver

My dad had a 1970 Buick Lesabre in his stable of cars. It was 1981 at the time, and my sister and I were youthful drivers. There was a reason we liked to borrow dad's old car. 455 X 4bbl reasons. we destroyed countless mid 70s to early eighties Camaro's, Firebirds, corvettes and mustangs. lol. It was also fun in the snow. Dad had to replace the rear end. I wonder if he knew.
Pit Crew

1974 Firebird Formula 455 RAM AIR
Pit Crew

My 70 442 W-30 dynoed at 414 hp/515 torque and is a beast. The Buick 455 was also also a great motor but the Oldsmobile 455 has a unique sound all it’s own, that’s my vote 1//2.


Another great article. The 455's deserve this, usually overshadowed by Chevy and Ford.
Advanced Driver

I have a 67 Buick Riviera with the 430, it is a quick car for the day, low 15 second quarter mile with a mild cam from Kenne Bell. I was all that in the late 80's Now it is nothing
Pit Crew

I love my buick 455. I have worked on just about all but the caddy and I chose Buick. I like the design of the buick motor and how easy it is to get to any part of it to work on. The power at the rpm range can be scary in a car under 3700lbs! The aftermarket support has grown a ton for all the these motors and attention put to addressing the individual flaws of each motor. But I would never build another one of these motors for any application other than its "different" or the "cool factor" and NOT following current powerplant trends.