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In 1970, GM lifted its 400ci limit for A-bodied intermediate cars. Oldsmobile took advantage of this by not only increasing the displacement of the standard 442 engine to 455ci, but by also offering a more modest, 320 horsepower high-compression 2-bbl 455ci V-8 (code L-33) on all its mid-size Cutlass models. The idea of installing the largest-available engine in a milder state of tune originated at Oldsmobile with the L-66 Turnpike Cruising option, which was offered on the Cutlass Supreme in 1967 in the form of a high-compression 300hp 2-bbl 400ci V-8, and on the 442 in 1968 with a low-compression 290hp 2-bbl 400ci V-8.
At the same time it made the L-33 option available on the Cutlass lineup across the board, Oldsmobile introduced a formal-roof notchback version of its A-body, and dubbed it the "Cutlass Supreme," a moniker that had represented the highest trim level, but not a unique body-style, in the Cutlass model line from 1967 through 1969.
The L-33 engine was only available on the Supreme body-style with the Y-79 SX option. An additional engine option available over and above the standard equipment of the SX, and available only on the SX in 1970, was engine option W-32, a 365 horsepower 4-bbl 455ci V-8, which came with a different-calibration transmission and a different standard final-drive ratio.
In February of 1970, midway through the model year, the L-33 2-bbl 455ci V-8 was discontinued, and in its place came the L-31 4-bbl 455ci V-8 as the standard engine with the Y-79 SX option.
Though both the L-31 and the W-32 were 455ci V-8's rated at 365 horsepower, it is clear from the specifications below that they were two very different engines. The L-31 was identical in specifications to the 455ci V-8 used in Oldsmobile's full-size 88 and 98 models, while the W-32 shared its specifications with the base 455ci V-8 engine from the 442. The biggest difference between the two engines are the camshaft, the size of the intake valves, the carburetor jetting and the advance curve on the distributor.
Like all other big-blocks in 1970 and 1971, the engine was painted Oldsmobile Blue, a color that is manufactured by Martin Senour Paints, and which is available through NAPA under part #7959 @$5.50 for 12oz can (my thanks to Tim Garst for this information).
In 1971, there was only one 455ci V-8 engine available in the Cutlass Supreme line as the standard engine in the Y-79 SX package: the L-32 low-compression 4-bbl engine, which shared its specification with engines from the full-size Oldsmobiles that year. The horsepower rating dropped to 320 horsepower gross, or 250 horsepower according to the new SAE net rating standards. As the specifications below show, the biggest reason for the drop in horsepower would be the lower compression ratio that would enable the car to run on regular unleaded gasoline. There was no optional engine for the SX in 1971.
In 1972, the 455ci V-8 engine, this time in 4-bbl form, was once again available across all Cutlass models, including the Supreme. Though the Y-79 SX option was dropped for 1972, that year saw perhaps the most performance-oriented Supremes yet. For starters, the 455 could be ordered with a 4-speed manual transmission in the Supreme hardtop for the first time. In addition, with the change of the 442 from a separate model to a single option (code W-29), a Supreme could be optioned as a 442, and even upgraded to the W-30 engine package, but only in convertible form.
The hardtop body-style was not left out of the picture, however, as the 1972 Hurst/Olds was built off of the Supreme body platform in both coupe and convertible form. Thus not only was the 300 (net) horsepower W-30 engine, designated by the code "X" in the VIN, available on the Cutlass Supreme convertible with the W-29 442 option, but there are a handful of Hurst/Olds hardtops that are rumored to have been built with the W-30 engine option as well. So even though the Y-79 SX option was discontinued in 1972, it carried on in spirit through the regular 455-equipped Cutlass Supreme coupes and convertibles, the 442-optioned Cutlass Supreme covertibles and the Hurst/Oldses that year.
If you have any corrections or additions to the above table (I am seeking confirmation on the W-32 carburetor number), please e-mail me so that I can correct this table.
