Oldsmobile V8s can be grouped into five “generations.” The company produced its first V8 – an L-head design – in the years 1916-1923. The year 1949 marked the return of Oldsmobile V8s with the famous “Rocket” engine. A major change in design and engineering of Oldsmobile V8s took place in 1964. The last two-valves-per-cylinder overhead valve Oldsmobile V8 came in 1990. In 1995, the fifth generation Oldsmobile V8s began with the double-overhead-cam Aurora engine. Oldsmobile also built 1929-1930 Viking V8s.
From 1916 through 1922, the only Oldsmobile V8 was a 246.7 cid L-head of Model 47 with a 233.7 cid V8 that made 60 hp. This was the only engine offered in 1923, when the Model 47 continued alone. The Oldsmobile V8 was then discontinued until 1949, except for the Viking engine, which was a more modern 90-degree V8 of 259.5 cid that developed 81 hp.
The advanced Oldsmobile Rocket V8 started a series of Oldsmobile engines that, along with the 1949 Cadillac V8, were the first post-war overhead valve V8s produced by General Motors. Like all other GM divisions, Oldsmobile continued building its own V8 engine family for decades, finally adopting the corporate Chevrolet 350 small-block and Cadillac Northstar engine only in the 1990s. All Oldsmobile-built V8s were manufactured at plants in Lansing, MI.
“Rocket V8” applies to engines used in all 1949-1990 Oldsmobile V8s, even though Oldsmobile stopped using that name in the late 1970s. When it was first installed in the “small” Olds 88 models, the Rocket engine turned that model into a “factory hot rod.” Some consider the Rocket 88 to be the first muscle car.
Whatever you call it, the Rocket V8 was hot. Bowing with 303 cubic inches, the engine was based on the engineering principles of GM genius Charles Kettering. It was even built in a factory known as the “Kettering Engine Plant.” The 303 had hydraulic lifters, an oversquare bore/stroke ratio, a counterweighted forged crankshaft, aluminum pistons, floating wristpins and a dual-plane intake manifold.
Over the years, this engine would be called by a variety of names like Rocket, Rocket 88, Golden Rocket, Sky Rocket, Super Rocket, 4-4-2 Rocket, Jetfire Rocket and Starfire Rocket. It was the first mass-produced overhead-valve V8 and started a long-lasting trend of using this type of engine in American cars.
All Rocket V8s use a 90-degree bank angle and most share common stroke dimensions: 3.4375˝ for early Rockets, 3.6875˝ for the next generation and 3.385˝ for a revised design that would be introduced in 1964. The Rocket V8 grew to 324 cid in 1954-1956 and 371 cid in 1957.
A two-barrel carburetor was standard; but high performance 324s came with a four-barrel carburetor. The 324 was shared with GMC trucks. The 312-hp J-2 Golden Rocket option of 1957-1958 included three two-barrel carburetors.
The J-2 Golden Rocket was introduced in mid-1957. The option cost $83-$94 depending on whether the car had stick shift or automatic drive. Owners who rarely engaged the vacuum operated front and rear carburetors experienced problems with the vacuum linkage on those carbs, as well as with clogged carburetors. I rented a ’57 Olds with J-2 from National Car Rental in Los Angeles. It had these problems and could hardly get out of its own way.
The 371 was bored out to 394 cid. It replaced the 371 in Super 88s and 98s for 1959-1960 and a de-tuned version was used in the 88 in 1961 and as well as in the 1962-’64 Dynamic 88. Until 1964, all of the Rocket V8 engines had a strong family resemblance in basic architecture. The main differences were in cubic inch displacement, compression ratios, carburetion setups, ignition systems, air cleaners, intake and exhaust manifolds, cylinder heads, and pistons.
From 1961-1963, Oldsmobile offered its own version of the Buick-designed, all-aluminum 215-cid V8 in the F-85 compact. Oldsmobile tagged it the Rockette, Cutlass and Turbo-Rocket and stressed it was made by Oldsmobile. The Oldsmobile had larger wedge shaped combustion chambers with flat-topped pistons. It had six bolts per cylinder and slightly larger intake valves with shafts and rockers that were unique to Oldsmobile. With an 8.75:1 compression ratio and a two-barrel carburetor, the Olds 215 had the same rated hp, 155 hp at 4800 rpm, as the Buick.
In 1962-’63 Oldsmobile brought out a turbocharged version of the 215. The small-diameter T5 turbo with integral wastegate was made by Garrett AiResearch and produced a maximum of 5 psi boost at 2200 rpm. The engine had 10.25:1 compression and a single-barrel carburetor. It was rated at 215 hp at 4600 rpm and 300 lb·ft at 3200 rpm. In development, the high compression ratio and the charged load created problems with spark knock on hard acceleration and led Olds to develop a novel water-injection system that sprayed metered amounts of distilled water and methyl alcohol (dubbed “Turbo-Rocket Fluid”) into the intake manifold air-stream to cool the intake charge.
Introduced for the compact F85 and the Jetstar models of 1964, a new 330-cid Oldsmobile V8 was a blend of old and new. It traced its ancestry to the Rocket V8 in terms of dimensions such as the distance between the cylinder bores and the crankshaft to camshaft span. That allowed the old tooling to be re-used. At the same time, the 330 was a more compact engine with entirely new cylinder head, block and manifold castings, new internal parts, and new valve gears. The options list also grew. For big cars, the 394 remained one more year.
The Gen 2 Rocket V8s of 1964-up were wedge-head engines with a unique combustion chamber that resulted from a six-degree valve angle. This very open and flat chamber was fuel efficient and clean burning. It was the only GM engine to meet emission standards with a carburetor all the way to 1990.
In 1965, the 330-cid Oldsmobile V-8 was bored and stroked to create another brand new engine – the “high deck” 425. There was also a new 400-cid 345-hp Oldsmobile V8 for the one-year-old 4-4-2 high-performance model. With muscle car fever in full swing, there were many different compression ratios, valve arrangements and carburetion options available.
The 400-cid Gen 2 Rocket V8 was the second tall-deck big-block Olds engine and was offered in two versions The early 400s of 1965-‘67 used a slightly oversquare bore and stroke for an overall displacement of 399.6 cubic inches. All pre-1968 engines had a forged steel crankshaft. The later 1968-’69 400s shared the bore and stroke dimensions with the 455, but used a very undersquare design that met GM’s displacement restrictions for mid-sized cars and also reduced tooling costs. The actual displacement is 399.9 cu. in.
The forged steel crank used in early 400s (and 425s) is more common than the late style (also used in 455s). Some 1968 and later Olds 400/455s were produced with forged steel cranks. These rare cranks have a J-shaped notch in the outside diameter of the rear flange. Cast iron cranks have a C-shaped notch.
The 425-cid Olds big-block V8 was the company’s first tall-deck big block. It was produced from 1965-’67. The standard 425 of 1965-1967 was called the Super Rocket. It was the most powerful Olds 88/98 engine and compression ratios up to 9.0:1 were available. A special Starfire 425 engine had a modestly different camshaft grind. This engine was only available in the Starfire model and a performance economy model called the Jetstar II. shared the Toronado’s 10.5:1 compression ratio. It also used the .921˝ lifter bore of the Toronado Rocket.
An Ultra High Compression Toronado Rocket version of the 425 was available in the 1966 Toronado. It had the same 0.921 in. diameter lifters as the first-generation Oldsmobile engine, rather than the standard 0.842˝ lifters that let engineers increase camshaft ramp speed to 385 hp without sacrificing idle or reliability. Unlike all other 425s, this version was painted slate blue metallic.
The biggest-ever Oldsmobile Rocket V8 was a stroked 400 that arrived in 1968 with 455 cid. The 425’s stroke was lengthened to 4.25 in. to create this engine. Olds engineers kept the retired 425-cid engine’s 4.126˝ bore. The 455 would produce between 275 and 400 hp in different configurations. In 1968, it was offered in five different horsepower ratings between 310 and 400. The 330 was also bored out in 1968 to create the Oldsmobile 350 V8 that powered F85 models, Cutlasses and Delmont 88s. It put up to 310 hp on tap.
Between 1968-’80, many Oldsmobiles were built with Rocket 350 V8s. These engines were completely different than other GM 350s. The name “Rocket” was actually erased from the air cleaner decal in 1975, when catalytic converters arrived. Early 1968-’70 Olds 350s are more sought after because of their heavier castings, beefier cranks and better flowing heads. The later 1977-’80 versions had lightweight castings, a thinner block with “windows” in the main bearing journals, crack-prone Pontiac-made heads and a lightened crankshaft.
The 400-cid engine disappeared in 1970, leaving behind only the 350- and 455-cid V8s. An EGR system was added to the Oldsmobile engines in 1973 and the following season a High Energy Ignition system was introduced as an option, only to become standard the following year.
All Oldsmobile V8s got a catalytic converter in 1975. Also introduced that year was an Oldsmobile-built 260-cid V8 for the new Omega compact. It was made by reducing the 350’s bore to 3.500˝. The 260 was designed for economy and it was the first engine option above the 3.8L Buick V6 that was standard in many Oldsmobile models by the late ‘70s. This was the first power plant to use the smaller Rochester Dualjet two-barrel carburetor. Production of the 260 V8 ended in 1982 when the 307 became the only gas V8 in Oldsmobile’s line.
A 400-cid V8 returned as a big Olds option for 1975, but it wasn’t the same one dropped in 1970. It was a Pontiac engine that was used only one year. Similarly, a new 305-cid V8 for the 1977 Omega was a Pontiac power plant.
Oldsmobile did build the 403-cid V8 first used in 1977 Cutlass, Delta 88 and 98 models. The Toronado version of the 403 for the same year was a bit special with 200 net horsepower. “Corporate” engines, such as the 301 cid Pontiac V8 in the 1979 Delta 88 and the 265-cid Pontiac V8 in the 1980 Delta 88 were a development of the 1980s, but Oldsmobile itself did produce the 305-cid V8 that appeared in many 1981 Oldsmobile models.
By 1986, a 307-cid engine was the only V8 that Oldsmobile offered. The Hurst/Olds version put out 170 net horsepower. The Olds-built 307 would disappear after 1990. After that, a Chevrolet-built 305 cid V8 was available, but only in Custom Cruiser station wagons.
No Oldsmobile V8s were marketed in 1993 or 1994. In 1995, the double overhead cam Aurora V8 made its debut. This all-aluminum V8 with sequential fuel injection produced 250 hp at 5600 rpm. It was a Cadillac Northstar spin off and it became the base V8 in the Aurora until the end of that model’s production history in 2001. That was also the end of Oldsmobile forever. ν