1973 Oldsmobile Cutlass Supreme 455 (top); 1973 Pontiac GTO (bottom). Images by the author.
Editor’s note: This or That enables us, in an idyllic world, to add a collectible vehicle into our dream garage on a weekly basis, but with a catch: We can only pick one vehicle from this pairing and it has to be for enjoyment purposes rather than as an investment.
This episode of This or That originates from what some consider to be the last bastion of Detroit’s second, and perhaps most profound, performance era: a 1973 Oldsmobile Cutlass Supreme versus a 1973 Pontiac GTO. Both are furnished with 455-cu.in. powerplants and were former Hemmings Muscle Machines feature cars.
Describing the performance cars of 1973 as “polarizing” could be – perhaps for many – quite an understatement. Cutting right to the chase, it’s almost impossible to lay blame for such a perspective on a single variable. There were emission regulations manufactures had to contend with, on top of new safety regulations that had an impact on overall designs. This in conjunction with growing insurance premiums. An oil embargo was looming. And, if nothing else, the muscle car populace had already had their kicks – they grew up, got married, bought a house and started a family. That’s a lot to absorb in a very short window, especially when one considers Detroit managers plan – typically – a few years in advance, predicting market trends as best they can. In spite of it all, the performance era still clung to the vine; albeit a far smaller doses; or so it seemed.
As easy as it is to criticize GM’s redesigned A-body Colonnades for 1973 today – they were built on a 112-inch wheelbase platform and weighed just under 4,100 pounds – when new, Oldsmobile’s Cutlass line was almost universally welcomed as a breath of fresh air, to the tune of roughly 219,000 copies, making it one of the best-selling cars of the year. A variety of engines were still inserted under the hood – detuned as they were – including the division’s 455 cubic inch big-block. Or rather a confusing number of them. As documented in our feature story by David Traver Adolphus and George Mattar,
The dealership would have told you there were two 455s available in a 1973 Cutlass, a 250hp U-code and a 270hp V-code, but there were more 455s offered in the Oldsmobile lineup. Even Oldsmobile didn’t seem to know what they all were, as there was conflicting or incorrect information in factory materials.
T-code (engine option L74): All Oldsmobile Custom Cruisers and Ninety-Eights, and some Delta 88s had a 225hp engine with a single exhaust. We haven’t seen it listed as a Cutlass Supreme option, but High Performance Cars tested a new Turbo Hydra-Matic 442 that it listed as a 225hp car.
U-code (L74): Oldsmobile Custom Cruisers, Ninety-Eights and Delta 88s were available with a dual exhaust 455 that developed 250hp.
U-code (L75): You’re most likely to see the 250hp U-code, which is what you got in any Cutlass model (Cutlass, S, Supreme or Vista Cruiser) if you checked the L75, automatic and air conditioning boxes. It was available on cars equipped with the Salon “European Touring” option package or the 442 appearance and handling option package. “The L75 was virtually the same engine that was in the 1973 full-size Oldsmobiles,” said Gary Campbell, the Oldsmobile Club of America’s 1973-’77 Cutlass tech advisor. The sole difference between an L74 and L75 is the “X and Z” dual exhaust manifold: “All 455 Cutlasses had dual exhaust, while most full-size Olds had single exhaust. The U-code 455 was also in the automatic with air conditioning W45-code Hurst/Olds.”
V-code (L77): Any four-speed 455 Cutlass got the top 270hp V-code. “The V-code was the highest performance 455 available in a 1973 Olds,” said Gary. “It was available in the Cutlass models with automatic and no air conditioning, or four-speed cars with or without air conditioning. It was also in the automatic, non-air-conditioning Hurst/Olds.” Don’t be surprised, however, if you see Oldsmobile factory material that lists this engine incorrectly as the L75.
W-code (L78): The Toronado 455 may sometimes be confused with the U-code, as they both have 250hp. There was a 250hp W45 (and possibly 270hp W46 without A/C) engine in the Hurst/Olds. A W-designation carried over internally from the 1972 air induction W-30 package, but late emissions regulation changes meant none sold. X-code: We’ve seen the W-code referred to as X-codes, too, but that was probably the Pontiac Super Duty 455.
While the assembly line is believed to have assembled 2,230 cars fitted with a Rocket 455 (exact production records are inconsistent), the topic of this week’s This or That was ordered with the V-code L77 edition of the 455: one of roughly 95 Oldsmobile Cutlass models built with the engine/trans combo. At the drag strip, this particular example has recorded 15.4 ET’s at the hands of its owner.
As to the 4,806 same-year GTOs, its order sheet was far less confusing. The one-year-only continuation of the legendary nameplate came standard with a 230-hp 400-cu.in. L78-code engine, which could have been installed in conjunction with a base three-speed manual, an optional Muncie four-speed manual or Turbo Hydra-Matic automatic. A few extra bucks could net you an additional 20 horses, complements of Pontiac’s 455-cu.in. L75 code D-port V-8; however this engine could only be had with a THM400 trans, as seen in our former feature car – one of 544 Colonnade GTOs built as such. Track ET’s were comparable to the aforementioned high-power Oldsmobile’s. No matter the engine, NACA ducts adorned the GTO’s hood, providing a racy vibe. Were they functional? Author Mike Bumbeck explained,
NACA ducts were originally designed to draw in air to a jet engine without creating resistance or turbulence. What worked for planes might just work for cars, so Pontiac built two NACA ducts into the 1973 GTO hood. Air was supposed to pass through the NACA ducts and get forced into the carburetor via ductwork. The induction system worked, but made too much V-8 music to sneak under the federal decibel limit set forth by the no-fun department. Pontiac left the NACA ports to draw air into the engine compartment, and allegedly offered the rest of the system as a dealer part. Legend passed down from the Colonnade Druids claims that only 10 fully functional systems were built, and only one is known to exist today.
Engines and ducts aside, the GTO was also fitted with improved front suspension geometry with taller front spindles. Bolstering its handling characteristics were 1.25-inch front and a 1-inch rear anti-roll bar. Power front discs, 11-inches in diameter, were now standard equipment, along with 15×7-inch steel wheels; five-spoke Rally-IIs and Honeycomb wheels were optional.
As it turned out, 1973 was hardly the end of the performance era. but for now, given the basic profile of each, which would you add to your stable and why?