Oldsmobile Torque Monster Engines

Oldsmobile built the Rocket V8 engine from 1949 through 1990. The Rocket and the 1949 Cadillac V8 were GM’s first post-war OHV crossflow cylinder head V8 engines. Long before the corporate Chevrolet 350 small-block and Cadillac Northstar engines, Olds built their own V8 engine family. The engine block and cylinder heads were cast by Saginaw Metal Casting Operations.

Early Rockets had a 3.4375 in stroke; later Rockets had a 3.6875 in stroke, and Generation 2 engines had a 3.385 in stroke starting in 1964. Small-block engines are 260 cu in 307 cu in 330 cu in 350 cu in and 403 cu in 400, 425, and 455 cu in. In order to increase displacement, V8s have a larger deck height). These “big-block” models are 1 inch taller and 1.5 in broader than their “small-block” counterparts.

The Rocket V8 was the subject of several automotive firsts and lasts. OHV V8 mass-produced in 1949.

Pre-1972 American passenger automobile engine stated horsepower and torque values were SAE “Gross,” not SAE “Net”

Gen. 1

Oldsmobile V8s were produced from 1949 until 1964. This generation’s engines share a same block and head size.


An over square bore: stroke ratio, aluminum pistons, floating wristpins, hydraulic lifters and a dual-plane intake manifold rounded out the 303 cubic inch engine. The 303 ran from 1949 to 1953. 3.75 in bore, 3.4375 in stroke. Although the Oldsmobile and Cadillac engines were not physically connected, many lessons acquired by one division were integrated into the other’s design, resulting in two engines noted for their great power-to-weight ratio, fuel economy, and smooth, robust, reliable running.

Former head engineer Charles Kettering’s name was to be used on the original Oldsmobile V8, but company policy disallowed it. Instead, the renowned Rocket was born, offered in Oldsmobile’s 88, Super 88, and 98 models. As a result, the division’s 88 models were nicknamed Rocket 88s.

The 303 was produced from 1949 to 1953. The 2-barrel carburetor 303 produced 135 hp and 253 lb. ft in 1949-1951, over 33% more power than the extremely popular and widely produced 100 hp 1949 Ford Flathead V8, while the 4-barrel carburetor 88 and Super 88 V8s produced 160 hp and 265 lb. ft. in 1953.


It was produced from 1954 to 1956. Bore was 3.875 in and stroke was 3.4375 in. Standard two-barrel carburetors; high-performance 324s had four-barrel carburetors. GMC trucks shared the 324.

The 1954 88 and Super 88 V8s produced 170 and 185 horsepower and 295 and 300 lb ft of torque.  The Super 88 and 98 had 202 horsepower of torque. The 324 skirted pistons were known to fail in engines constructed in early 1955 due to the cast aluminum skirt separating from the steel inner bracing. This issue arose after the engine had 50,000 miles (80,000 km) on it. This was discovered in late 1956. In 1956, the 88 gained 230 horsepower and 340 lb ft while the Super 88 and 98 gained 180 hp and 350 lb. ft.


The 371 was introduced in 1957 and was standard on all Olds models through 1960. Its bore was expanded to 4.0 in and stroke to 3.6875 in. These 371s had green painted valve covers. 4-barrel variants had 9.25:1 compression in 1957 and 10:1 compression in 1958 producing 277 horsepower and 400 lb ft respectively. A 1958 2-barrel variant made 265 horsepower and 390 lb. ft, however the high preload valve spring tensions caused early camshaft breakdowns. The 1959 and 1960 88 versions had 270 horsepower and 390 lb. ft of torque, respectively, due to the AMA’s restriction on factory-sponsored racing. It was discontinued in 1961.  From 1957 to 1959, the “370” had 232 gross HP at 4200 RPM and 355 gross lbs.-ft at 2600 RPM.

Golden Rocket J-2

The 1957 and 1958 J-2 Golden Rockets had three two-barrel carburetors with a vacuum-operated linkage. Only the middle carburetor had a choke and was mechanically attached to the throttle pedal. A 60° or more center carburetor opened the front and rear carburetors concurrently. These carburetors were either open or closed. The J-2 had a thinner head gasket, increasing compression to 10.0:1. It was rated at 312 horsepower at 4600 rpm and 415 lb ft at 2800 rpm. The J-2 option cost $83 with the three-speed manual and $314 with the automatic. As a result of the linkage and carburetor throats becoming clogged, some J-2 cars had the front and rear carburetors removed and plugged off. Correct tuning was also a headache. Because it was costly to construct, Oldsmobile dropped it in 1958.


The largest first-generation Rocket bore 4.125 in. 394s were available on various Olds vehicles from 1959-1964. Starting in 1961, special high-compression 4-barrel 394s were offered. The standard engine gained 315 horsepower despite a quarter point decrease in compression to 9.75:1.

In 1959 and 1960, the 394 replaced the 371 in Super 88 and 98 automobiles, while a detuned version was utilized in 1961 and 1962-1964.

Sky Rocket

The 1961-1963 Sky Rocket had a 394 cu in four-barrel engine. It had 325 horsepower and 435 lb. ft in 1961, and 330 hp and 440 lb ft in 1962-1964. A 345 horsepower 10.5:1 variant was made in 1963.

Aluminum 215

From 1961 to 1963, Oldsmobile built its own 215 cubic inch aluminum V8 engine for the F-85 small. Oldsmobile called it the Rockette, Cutlass, or Turbo-Rocket, while Buick called it the Fireball or Skylark.  The Oldsmobile engine was based on the Buick engine, but with wider wedge combustion chambers, flat-topped pistons, six bolts per cylinder, and somewhat larger intake valves. The Olds 215 had the same 155 horsepower at 4800 rpm and 220 ft lb of torque at 2400 rpm as the Buick 215. In manual form, the Olds 215 had 4-barrel carburetor and 10.25:1 compression, which resulted in 185 horsepower and 230 lb. ft at 4800 rpm. In an automatic, the Olds 215 produced 195  horsepower and 235lb ft with a 4-barrel carburetor and 10.75:1 compression. The Buick had 200 horsepower and an 11:1 compression ratio. The Buick 215 V8 became the well-known Rover V8, which still uses Buick-style pistons, heads, and valve train gear.

Using a Buick 300 crankshaft, new cylinder sleeves, and non-GM parts, hot rodders discovered the 215 could be expanded to 305 cu in.


Oldsmobile produced a Turbo-Rocket variant of the 215 in 1962 and 1963. The turbocharger on the V8 engine was a Garrett T5 with integral waste gate, rated at 5 psi at 2200 rpm. With an 11:1 compression ratio and a single-barrel carburetor. At 4600 rpm, it produced 215 horsepower and 300 lb ft of torque. In order to cool the intake charge, Olds developed and used a revolutionary water-injection system that sprayed metered volumes of distilled water and methyl alcohol into the intake manifold airstream. Without a fluid reservoir, a sophisticated double-float and valve mechanism in the Turbo-Rocket Fluid path limits boost pressure by closing a second butterfly Unfortunately, many customers did not keep the reservoir filled or had technical issues with the turbocharger system, causing many to be removed and replaced with a traditional 4-barrel carburetor and manifold.

Gen. 2

The second Oldsmobile V8 generation ran from 1964 through 1990. Most of these engines had the same bore centers and deck height on “big-block” versions, 10.625 in The 3.0 in main bearing journal was added to the Big-block and Diesel models for added strength. Generation 2 small-block Olds V8s have a 3.385 stroke From 1968, both the 400 cu in and 455 cu in big blocks had a stroke of 4.25 in ,with crankshaft material changed to cast iron save in a few odd cases.

These were wedge-head engines with a 6° valve angle and a unique combustion chamber. The 23° small-block Chevy and 20° Ford small-block wedge heads were substantially flatter. This open, flat chamber was fuel efficient and had low emissions. Until 1990, it was the only GM engine to meet US pollution requirements with a carburetor.


Oldsmobile Jetfire Rocket V8 330 cu in 1964-1967. It launched a 3.385 in stroke and a 3.938 in bore, one year before the tall deck 425. Gold 330s had forged steel crankshafts. 2- and 4-barrel variants just had a balancer hub with no rubberized outer ring.


The 400 cu in tall-deck Olds was the second. The 400 CID engine came in two flavors:

“Early” 400s had a 4.000 in bore and 3.975 in stroke for a 399.6 cubic inch displacement. Forged steel crankshafts were utilized before 1968.

They employed a 3.87 in bore to comply with GM’s displacement constraints in the A-body automobiles while also saving tooling expenses. 399.9 cubic inch displacement is close to the older engine Many enthusiasts dislike this “later” 400 because of the power band characteristics produced by the under square shape, despite the fact that the mild 250/264 duration cam and the crankshafts being composed of less lasting high nodular iron composition.

With few instances, early 400s used forged steel crankshafts while later 400s used cast iron crankshafts. The “J” shaped notch in the OD of the rear flange distinguishes these unusual cranks from cast iron cranks. Olds 400s from 1965-1969 were bronze.

4-4-2 Rocket

The 1966-1967 4-4-2 400 cu in V8 has B and C cast large-valve cylinder heads, larger hydraulic lifters, and push rods than the normal Olds Rocket V8. There were two engine options available in 1966: the Rochester 4-barrel and the L69 tri-2 barrel. In 1967, a W30 camshaft, 4-barrel, and outside air induction were claimed to produce 360 horsepower. The cylinder heads had V and G stamped on them.


The 425 cu in big block was produced from 1965 to 1967. It’s possibly the finest engine Olds ever manufactured, despite never being used in a “muscle car”. The bore and stroke were 4.126 in (104.8 mm). The Toronado 425s of 1966 and 1967 were painted light blue. They had forged steel crankshafts with harmonic balancers.

Super Rocket

The 425 cu in engine was the most powerful option for the 1965-1967 Oldsmobile 88 and 98. For 310 horsepower 9.0:1 was available, and 10.25:1 for 360 hp.


Starfire had a 425 cu in V8 from 1965-1967. This engine has a different camshaft profile than the standard super high compression engine with factory dual exhaust. This engine was only found in the Olds Starfire and the Jetstar I. The Toronado Rocket has a 10.5:1 compression ratio. It also employed the Toronado Rocket’s.921 lifter bore.

Tornado Rocket

The 425 cu in Ultra High Compression Toronado Rocket V8 was made for the 1966 Toronado. Since the lifters were 0.921 in in diameter, rather than the typical 0.842 in , engineers were able to raise the camshaft’s ramp speed for higher power without sacrificing idle or reliability. This 425 was painted slate blue metallic, unlike any other.


The 425’s stroke was extended to 4.25 in (to create the Rocket 455 for 1968. It used the 425’s 4.126 in bore to create 275-400 horsepower. The color was initially red, save for the Toronado, which was metallic blue at first, then nonmetallic blue. After 1974, the “Rocket” name was removed from the air cleaner decal. Although manufacture halted in 1976, a few were kept in stock until 1978 for use in motor homes, boats, and irrigation equipment.


The Rocket 350 was a 1968-1980 GM division 350 that was completely unique. It had a 4.057 in bore and a 3.385 in stroke for 350 cu in .160-325 horsepower  1975-1976 350s were metallic blue like the 455; 1977-1980 models were GM Corporate Blue. The “Rocket” name was removed off the air cleaner decal in 1975, along with the catalytic converter. The 1968-1976 Olds 350s have heavier castings, beefier crankshafts, and better flowing heads.

It had a thinner block with wide “windows” in the main bearing bulkheads, crack-prone cylinder head castings from Pontiac Motor Division and a lighter crankshaft from 1977 to 1980.


It was used in the 1976 Olds Cutlass “S”, the 1979 Hurst/Olds models, and the 1980 “4-4-2”. This car had a 4 barrel carburetor and made 160-170 horsepower.


With the Olds small-block standard deck and 3.385 in stroke, the 403 cu in small block superseded the 455 big block Olds in 1977. The bore was so large that the cylinder walls were siamesed, like in the Chevrolet 400 V8. This sometimes caused overheating. Early 403s had metallic blue paint like the 455, but most had GM Corporate Blue.

The Olds 403 was utilized by Buick, Pontiac, and Oldsmobile until 1979. 185 horsepower 320 lb ft The 403 engine in the 1977 Toronado has a crank-triggered ignition system.

The “adjacent sensor” a particular distributor, an engine temperature sensor, and a basic computer mounted under the dashboard are all unique to this system.