Oldsmobile V8 engine

Oldsmobile V8 engine
The 1966Toronado's 425 V8, the first post war front-wheel drive V8 application.

The Oldsmobile Rocket V8 was the first post-war OHV V8 at General Motors. Production started in 1949, with a new generation introduced in 1964. Like Pontiac, Olds 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 V-8's were manufactured at plants in Lansing, Michigan.

All Oldsmobile V8s use a 90° bank angle, and most share a common stroke dimension: 3.4375 in (87.31 mm) for early Rockets, 3.6875 in (93.66 mm) for later Generation 1 engines, and 3.385 in (86.0 mm) for Generation 2. The 260 cu in (4.3 l), 307 cu in (5.0 l), 330 cu in (5.4 l), 350 cu in (5.7 l) and 403 cu in (6.6 l) engines are commonly called small-blocks.[1] 400 cu in (6.6 l), 425 cu in (7.0 l), and 455 cu in (7.5 l)[2] V8s have a higher deck height (10.625 in (27.0 cm) versus 9.33 in (23.7 cm)) to accommodate a 4.25 in (108 mm) stroke crank to increase displacement. These taller-deck models are commonly called "big-blocks", and are 1 in (2.5 cm) longer and 1.5 in (3.8 cm) wider than their "small-block" counterparts.[3]

The Rocket V8 was the subject of many first and lasts in the automotive industry. It was the first mass-produced OHV V8 in 1949; and was the last carbureted V8 passenger car engine in 1990.

The factory painted "small-blocks" gold or blue (flat black on the late model 307 cu in (5.0 l)),[4] while "big-blocks" could be red, green, blue, or bronze.[5]


Generation 1

The first generation of Oldsmobile V8s ranges from 1949-1964. Each engine in this generation is quite similar with the same size block and heads.


Rocket V8 303 engine

The 303-cubic-inch (5.0 L) engine had hydraulic lifters, an oversquare bore:stroke ratio, a counterweighted forged crankshaft, aluminum pistons, floating wristpins, and a dual-plane intake manifold. The 303 was produced from 1949-1953. Bore was 3.75 in (95 mm) and stroke was 3.4375 in (87.31 mm). Cadillac used a distantly related engine which appeared in three different sizes through to the 1962 model year; though the Oldsmobile and Cadillac motors were not physically related, many lessons learned by one division were incorporated into the others design, and the result were two engines known for their excellent power-to-weight ratio, fuel economy, and smooth, strong, reliable running.

The original Oldsmobile V8 was originally to be advertised as "Kettering Power" after chief engineer Charles Kettering, but company policy disallowed the use of his name. So the engine was sold as the Oldsmobile Rocket. The engine was available in Oldsmobile's 88 and Super 88 models, which acquired the nickname Rocket 88.

The 303 was available from 1949 through 1953. 1949 through 1951 "88" 303's came with a 2-barrel carburetor for 135 hp (101 kW) and 253 lb·ft (343 N·m). 1952 88 and Super 88 V8s used a 4-barrel carburetor for 160 hp (120 kW) and 265 lb·ft (359 N·m), while 1953 versions upped the compression from 7.5:1 to 8.0:1 for 165 hp (123 kW) and 275 lb·ft (373 N·m). For comparison, a 1949 Ford Flathead V8 produced just 100 hp (75 kW).



The 324-cubic-inch (5.3 L) version was also produced from 1954 until 1956. Bore was increased to 3.875 in (98.4 mm) (same as the 283 Chevy) and stroke remained the same at 3.4375 in (87.31 mm). All high performance 324s came with 4-barrel carburetors. The 324 was shared with GMC trucks.

The 1954 88 and Super 88 V8s used an 8.25:1 compression ratio for 170 and 185 hp (126 and 137 kW) and 295 and 300 ft·lbf (399 and 406 N·m) respectively.

The 1955 upped the compression to 8.5:1 for 185 hp (138 kW) and 320 lb·ft (430 N·m) in the 88 and 202 hp (151 kW) and 332 lb·ft (450 N·m) in the Super 88 and 98. For engines built during the first part of 1955, the 324 skirted pistons had a reputation for failing due to the cast aluminum skirt separating from its steel interior brace. This problem did not appear until the engine had over 50,000 miles (80,000 km) on it. By late 1956, many Olds dealers learned about the problem.

Compression was up again in 1956 for 230 hp (170 kW) and 340 lb·ft (460 N·m) in the 88 and 240 hp (180 kW) and 350 lb·ft (470 N·m) in the Super 88 and 98.



A special 370-cubic-inch (6.1 L) variant called the 370 was used in GMC trucks alone, not shared.


Making its debut in 1957 as standard equipment on all Olds models,[6] the 371 was produced through 1960. Bore was now 4.0 in (100 mm) (same as the 327 and 350 Chevys) and stroke was increased to 3.6875 in (93.66 mm) for 371 cu in (6.1 L). 1959 and 1960 371s used green painted valve covers. 4-barrel models used 9.25:1 compression in 1957 and 10:1 in 1958 for 277 hp (207 kW) and 400 lb·ft (540 N·m) and 305 hp (227 kW) and 410 lb·ft (560 N·m) respectively. A 1958 2-barrel version was still impressive at 265 hp (198 kW) and 390 lb·ft (530 N·m), but had problems with early camshaft failures due to the high preload valve spring forces. Then, power nosed downward for the 1959 and 1960 88 model: 270 hp (200 kW) and 390 lb·ft (530 N·m) for 1959 and 240 hp (180 kW) and 375 lb·ft (508 N·m) for 1960. It was no longer available in cars in 1961.[7]

The 371 was also used in GMC trucks.


J-2 Golden Rocket

Introduced in the middle of the 1957 model year,[8] the 1957 and 1958 J-2 Golden Rocket had three two-barrel (twin choke) carburetors with a vacuum-operated linkage. Only the center carburetor was mechanically connected to the throttle pedal, and it was the only one equipped with a choke. When the center carburetor was opened to 60° or more engine vacuum drawn from the windshield wiper pump would simultaneously open the front and rear carburetors. These carburetors did not open progressively; they were either open or closed. The J-2 engine also had a slightly thinner head gasket, raising compression to 10.0:1. It was advertised with gross power and torque ratings of 312 hp (233 kW) at 4600 rpm and 415 lb·ft (563 N·m) at 2800 rpm. Oldsmobile charged $83 for the J-2 option with the three-speed manual (or in the 98),[9] $314 dollars with the automatic.[10]

In practice, owners who did not regularly drive hard enough to engage the front and rear carburetors experienced problems with the linkage and carburetor throats becoming clogged, and some J-2-equipped cars had the front and rear carburetors removed and blocked off. Moreover, correct tuning was a continual headache. The package was expensive to produce, and Oldsmobile discontinued it after 1958.


Bore was up to 4.125 in (104.8 mm) for the largest first-generation Rocket, the 394 cu in (6.5 L). 394s were produced from 1959-1964 and were available on many Olds models. Most 394s used 2-barrel carburetors. Power was up to 315 hp (235 kW), even though compression was down a quarter point, to 9.75:1.[11]

The 394 replaced the 371 in Super 88 and 98 cars for 1959 and 1960 and a detuned version was used in the 88 for 1961 and the Dynamic 88 for 1962-1964.


Sky Rocket

The 1961 through 1963 Sky Rocket (and 1964 Rocket) was a 394 cu in (6.5 L) engine. The 10:1 compression 1961 model produced 325 hp (242 kW) and 435 lb·ft (590 N·m), while the 10.25:1 1962-1964 version upped power to 330 hp (250 kW) and 440 lb·ft (600 N·m). A special 1963 10.5:1 version was also produced with 345 hp (257 kW).



The 1964 Starfire produced 345 hp (257 kW) and 440 lb·ft (600 N·m) for the 1963-4 Starfire and 98 Custom-Sports Coupe. It was optional on 1964 98s and Super 88s.

Aluminum 215

From 1961-1963, Oldsmobile manufactured its own version of the Buick-designed, all-aluminum 215 engine for the F-85 compact. Known variously as the Rockette, Cutlass, and Turbo-Rocket by Oldsmobile (and as Fireball and Skylark by Buick),[12] it was a compact, lightweight engine measuring 28 in (71 cm) long, 26 in (66 cm) wide, and 27 in (69 cm) high (same as the small-block Chevy),[13] with a dry weight of only 320 lb (150 kg).[14] The Oldsmobile engine was very similar to the Buick engine, but not identical: it had larger wedge(rather than hemispherical)-shaped combustion chambers with flat-topped (rather than domed) pistons, six bolts rather than five per cylinder head, and slightly larger intake valves; the valves were actuated by shaft-mounted rocker arms like the Buick and Pontiac versions, but the shafts and rockers were unique to Oldsmobile. With an 8.75:1 compression ratio and a 2-barrel carburetor, the Olds 215 had the same rated hp, 155 hp (116 kW) at 4800 rpm, as the Buick 215, with 220 ft·lbf (300 N·m) of torque at 2400 rpm. With a 4-barrel carburetor and 10.25:1 compression, the Olds 215 made 185 hp (138 kW) at 4800 rpm and 230 lb·ft (310 N·m) at 3200 rpm with a manual transmission. With a 4-barrel carburetor and 10.75:1 compression, the Olds 215 made 195 hp (145 kW) at 4800 rpm and 235 lb·ft (319 N·m) at 3200 rpm with an automatic. The Buick version was rated at 200hp with an 11to1 compression ratio.

The basic Buick/Olds 215 V8 went on to become the well known Rover V8, which still remains in limited production. The Range Rover V8 utilized the Buick-style pistons, heads, and valve train gear.

The Oldsmobile engine block formed the basis of the Repco 3-liter engine used by Brabham to win the 1966 and 1967 Formula One world championships. The early Repco engines produced up to 300 bhp (220 kW), and featured new SOHC cylinder heads and iron cylinder liners. The 1967 and later versions of the Repco engine had proprietary engine blocks.

In the mid-1980s, hot rodders discovered the 215 could be stretched to as much as 305 cu in (5 l), using the Buick 300 crankshaft, new cylinder sleeves, and an assortment of non-GM parts.[15] It could also be fitted with high-compression cylinder heads from the Morgan +8. Using the 5 liter Rover block and crankshaft, a maximum displacement of 317.8 cu in (5,208 cc) is theoretically possible.[16]

Turbo Jetfire

In 1962 and 1963 Oldsmobile built a turbocharged version of the 215. The small-diameter Garrett T5 turbocharger was manufactured by Garrett AiResearch and produced a maximum of 5 psi (34 kPa) boost at 2200 rpm. The engine had 10.25:1 compression and a single-barrel carburetor. It was rated at 215 hp (160 kW) at 4600 rpm and 300 lb·ft (410 N·m) at 3200 rpm. The high compression ratio created a serious problem with spark knock on hard throttle applications, which led Olds to use a novel water-injection system that sprayed small amounts of distilled water and methyl alcohol (dubbed "Turbo-Rocket Fluid") into the combustion chambers to cool the intake charge. If the fluid reservoir was empty, a complex double-float and valve assembly in the Turbo-Rocket Fluid path would set a second butterfly (positioned between the throttle butterfly and the turbocharger) into the closed position, limiting the amount of boost pressure. Unfortunately, many customers did not keep the reservoir filled, or had mechanical problems with the turbocharger plumbing.

The turbocharger was offered only in a special Jetfire model, which was the first turbocharged passenger car offered for public sale. Only 9,607 were sold in two model years, and many were converted by dealers to conventional four-barrel carbureted form.

Generation 2

The second generation of Oldsmobile V8s was produced from 1964-1990. Most of these engines were very similar, using the same bore centers, although "big-block" versions were produced with a 10.625 in (269.9 mm) deck height rather than 9.33 in (237 mm). Big-block and Diesel versions also used a larger 3.0 in (76 mm) instead of 2.5 in (64 mm) main bearing journal for increased strength. All generation-2 small-block Olds V8s used a stroke of 3.385 in (86.0 mm). The big-block engines initially used a forged crankshaft with a stroke of 3.975" for the 1965-1967 425 and 400 CID versions; starting in 1968, both the 400 cu in (6.6 L) and the 455 cu in (7.5 L) big blocks used a stroke of 4.25 in (108 mm), with crankshaft material changed to cast iron except in a few rare cases.

These engines, while being a wedge-head, had a unique combustion chamber that resulted from a valve angle of only 6°. This was much flatter than the 23° of the small-block Chevrolet and 20° of the Ford small-block wedge heads. This very open and flat chamber was fuel efficient and had lower than average emissions output. It was the only GM engine to meet US emission standards using a carburetor all the way up to 1990.

Jetfire Rocket

The first second-generation Olds V8 was the 1964 330 cu in (5.4 L) which Olds called the "Jetfire Rocket". It introduced the standard 3.385 in (86.0 mm) stroke and used a 3.938 in (100.0 mm) bore and was produced through 1967. 330s were painted gold and had forged steel crankshafts. While the 4 barrel versions had a larger diameter harmonic damper, the 2 barrel versions used only a balancer hub without the rubberized outer ring.


The 400 cu in (6.6 L) version was the second tall-deck "big-block" Olds. Two distinct versions of the 400 CID engine were made:

  • 1965-1967 Early 400's used a slightly over-square 4.000 in (101.6 mm) bore and 3.975 in (101.0 mm) stroke. All the pre-1968 engines used a forged steel crankshaft.
  • 1968 and 1969 400's shared the Olds big-block standard 4.25 in (108 mm) stroke with the 455 but used a very undersquare 3.87 in (98 mm) bore to comply with GM's displacement restrictions in the A-body cars and reduce tooling costs. This Later 400 is considered by many enthusiasts to be less desirable because of the powerband characteristics induced by this exceedingly undersquare format, and the fact that the crankshafts were now made of less durable cast iron material. Early 400's used the same forged steel crankshaft as the 425's, while the Later 400's used the same cast iron crankshaft of the 455's, with rare exception- some 1968 and later Olds 400/455's were produced with forged steel crankshafts. These rare cranks can be readily spotted by the "J" shaped notch in the OD of the rear flange; cast iron cranks have a "C" shaped notch.

All 1965-1969 Olds 400's were painted bronze.

4-4-2 Rocket

The 1967 4-4-2 Rocket was a 400 cu in (6.6 L) V8.


The 425 cu in (7.0 L) big-block was the first tall-deck "big block," produced from 1965 through 1967. It is arguably the best engine Olds made in the muscle car era, although it never made it into a "muscle car". It used a 4.126 in (104.8 mm) bore and 3.975 in (101.0 mm) stroke. Most 425s were painted red, though the 1966 and 1967 Toronado units were light blue. All 425 engines were fitted with forged steel crankshafts with harmonic balancers.

Super Rocket

The standard 1965-1967 425 cu in (7.0 L) was called the Super Rocket, and was the most powerful engine option for the Oldsmobile 88 and 98 of 1965-1967. Compression ratios of 9.0:1 at 310 hp (230 kW) or 10.25:1 at 360 hp (270 kW) were available in the U.S.


A special 1965-1967 425 cu in (7.0 L) V8 was the Starfire engine. The main distinguishing features of this engine were a slightly different camshaft profile from the standard ultra high compression engine and factory dual exhaust. This engine was only available in the Oldsmobile Starfire. It shared the same compression ratio of the Toronado Rocket at 10.5:1. It also used the .921 in lifter bore size of the Toronado Rocket.

Toronado Rocket

Another 1967 425 cu in (7.0 L) V8 was the Ultra High Compression Toronado Rocket. Unlike all other 425s, this version was painted slate blue metallic. The Toronado 425 engines had the same 0.921 in (23.4 mm) diameter lifters of the first-generation Oldsmobile engines rather than the standard 0.842 in (21.4 mm). This let the engineers increase the ramp speed of the camshaft for more power, 385 hp (287 kW), without sacrificing idle or reliability.


A larger big-block was introduced for 1968 as the Rocket 455 at 455 cu in (7.5 L) to replace the 425s. It kept the 425's 4.126 in (104.8 mm) bore and bumped the stroke to 4.25 in (108 mm). 1968-1969 455s were painted red, except in the Toronado, where they were painted slate blue metallic, while 1970-1976 versions were metallic blue. The "Rocket" name disappeared from the air cleaner identification decal after 1974. Although production of the 455 ended in 1976, a small number were produced through 1978 for power equipment use. Output ranged from 275 to 400 hp (199 to 298 kW).



Produced from 1968-1980, the Rocket 350 was entirely different from the other GM divisions' 350's. It used a 4.057 in (103.0 mm) bore and Oldsmobile small-block standard 3.385 in (86.0 mm) stroke for 350 cu in (5.7 L). 1968-1974 350s were painted gold; 1975-1976 350s were metallic blue like the 455; 1977-1980 models were painted GM Corporate Blue. The "Rocket" name disappeared from the air cleaner decal in 1975, the same year that the catalytic converter was added to the emission control systems. Output ranged from 160-325 hp (119-242 kW). The early Oldsmobile 350s made from 1968-1976 are more desirable engines with heavy castings, beefier crankshafts, and better flowing heads. The later 1977 thru 1980 350 had the "lightweight" castings, including a thinner block with large "windows" in the main bearing bulkheads, crack-prone head castings which were actually manufactured by Pontiac Motor Division (castings are marked "PMD"; these heads were also used on the 260), and a lightened crankshaft.

The Oldsmobile 350 was produced with an analog electronic port fuel injection system, introduced in the Cadillac Seville of 1976.



Oldsmobile's own L34 350-cubic-inch (5.7 L) V8 was used in the 1979 Hurst/Olds models. The L34 used a 4-barrel carburetor and produced 160–170 hp (120–130 kW) and 275 ft·lbf (373 N·m).

LF9 Diesel

The LF9 was a 350 cu in (5,737 cc) diesel V8 produced from 1978-1985.


  • 350N 1978–1985 Chevrolet, Buick, Oldsmobile, Pontiac, Cadillac, and Checker Marathon cars
    • Early 120 hp (89 kW) 220 ft·lbf (300 N·m) torque
    • Later 105 hp (78 kW) and 205 ft·lbf (278 N·m) torque
  • 350N 1978–1980 GMC and Chevrolet light trucks "pickups"
    • 125 hp (93 kW) and 225 ft·lbf (305 N·m) torque


  • 1978–1980 Early block Identified by "D" cast into both sides of block
    • Up to 125 bhp (93 kW)
    • external EGR from 1978–1981 (single stud air cleaner)
    • internal EGR from 1982–1985 (two stud air cleaner)
    • Used a conventional flat tappet hydraulic camshaft/flat tappet hydraulic lifters which required 3,000 mi (4,800 km) oil change intervals.
  • 1981–1985 Improved block Identified by "DX" cast into both sides of block.
    • Up to 105 bhp (78 kW)
    • Internal EGR
    • All 5.7 diesels from 1978–1985 used 1/2" diameter cylinder head bolts.
    • Longer main bolts with fully tapped holes in block.
    • Newly introduced roller lifters/rollerized camshaft extended oil change intervals to 5,000 mi (8,000 km).

Diesel differences;

The Oldsmobile diesel is believed by some to be a converted gasoline engine. While they share the same bore and stroke and some external bolt patterns (transmission and exhaust manifolds) they are quite different.

GM began with a substantially different bottom end when compared with its gasoline cousin.

  • Diesel blocks
    • 3" diameter injection pump mount is cast into the top of the lifter valley.This casting was part of the engine block.
    • Camshaft nose modified to incorporate injection pump drive gear.
    • A round plastic button in the 1981-1985 DX blocks was used with a stiff spring to prevent the camshaft from "walking" back and forth.
    • Block castings are much thicker and heavier. It's possible to overbore the cylinders by 0.125in without sonic testing.
    • Solid heavy cast main webs were used.
    • Reputedly, GM used a higher nickel cast iron alloy for the block and heads.
  • Diesel crankshafts
    • Cast nodular iron used in all Olds diesel crankshafts.
    • Main bearing journal diameter was increased to 3.0" which made that area the same as that of the Olds 455 crankshaft.
    • Vibration damper modified to allow eccentric for crank-driven fuel lift pump
  • Diesel pistons and rods
    • Diesel rods are shorter at 5.886" long.
    • Diesel connecting rods use a bronze bushing with a full floating piston pin.They did not use press fit piston pins like many gasoline engines do.Snap-rings are used to retain the piston pin within the piston.
    • Diesel pistons have large valve reliefs with a flame slot and a steel insert to reinforce the top piston ring area.
  • Fuel systems
    • No OEM fuel/water separator was factory installed on any Olds Diesel.
    • Crank eccentric driven fuel lift pump mounted in same location as gasoline fuel pump.
    • Fuel line heater between lift pump and filter.
    • Intake mounted 10 micrometer fuel filter.
    • Stanadyne Roosamaster DB2 mechanical diesel injection pump.
    • 1978-79 Pencil Injectors held in by a mounting clamp.
    • 1980-85 Poppet injectors thread into the cylinder head like a spark plug.
  • Heads
    • The same 10-head bolt pattern as their smallblock gasoline cousins.
    • The same exhaust manifold bolt pattern as their smallblock gasoline cousins.
    • Precombustion chambers were used since this engine is a indirect-injected design.
    • Valve springs contained a vibration dampener with rotators.
  • Head variations
    • Very early castings were stamped D3 and used 5/16" injector hold down retaining bolts and clamps.
    • D3A castings were created a little later and used 3/8" injector hold down bolts and clamps.
    • Both D3 and D3A heads accepted external EGR and pencil injectors.
    • Some D3A heads accepted poppet injectors as well.
    • D3B Later heads
      • All had internal EGR
      • Pencil or poppet injectors
      • 1 or 2 locating dowels

The Oldsmobile diesel gained a reputation for unreliability and anemic performance that badly damaged the North American passenger diesel market for the next 20 years.[17][18]

Oldsmobile diesel problems

Head bolts

GM used "torque to yield", commonly known as "stretch" or "angle torque", head bolts. This allowed the bolt pattern to remain the same as the gas powered counterpart with an increase in clamping load when compared to standard head bolts. A total of 10 bolts per head were used, four per cylinder with the center three pairs shared. This permitted the use of the same tooling and reduced setup costs. This design did not provide adequate clamping force under the severe conditions to which these engines were subjected. Overheating or excessive cylinder pressure could breach the seal of the head gasket and in severe cases break the bolts.

High strength aftermarket head bolt sets from Victors are now available to make the engine more reliable in this area.

Pump timing

The Stanadyne injection pump was driven with the use of a short stubby shaft with a built in helical gear which meshed with a gear on the front section of the camshaft. With high mileage,the timing chains tended to stretch a little (like any other timing chain) and the injection pump timing could become less than perfect. The pump timing can be adjusted dynamically with the use of a Snap-on MT480 analog diesel timing meter or with one of the more modern meters used today.

Water in fuel

Arguably a major portion of the LF9 engine's problem could have been simply avoided by using a water separating fuel filter. The lack of water separators was a fuel system deficiency across GMs' light duty diesel lineup into the late 1980's.

Water will rust the steel internals of the fuel system. Rust will damage the precision parts in diesel fuel injection pumps and high pressure diesel injectors causing erratic operation. Injecting fuel too much prior to TDC on the compression stroke will cause pressure conditions similar to pre-ignition / detonation in gasoline engines. Water in varying amounts will also be injected with the fuel charge. Any rust in the steel fuel lines, fuel filter, pump etc can damage replacement parts and continue to cause injection cycles out of time.

Consumer created fuel problems

Water in gasoline fuel systems can be addressed by adding anhydrous alcohol [drygas] to the fuel. This technique does not work with diesel fuel. Some consumers used drygas in their diesels to combat the water, but the Alcohol in drygas accelerated the wear of the governor flex rings inside the early Stanadyne DB injection pumps. These pumps included an ignition advance mechanism based on pump housing fuel pressure. The housing pressure was affected by fuel return flow. Pieces of a damaged governor flex ring lodged in the fuel return check ball assembly. The sometimes intermittently blocked return line combined with a damaged governor caused erratic ignition timing. The flex ring governor was replaced, by Stanadyne in 1985, with a much improved Elastomer Insert Drive Governor Assembly commonly referred to as an EID. The EID is a service replacement part that eliminates the disintegrating flex ring.[19]

The above mix of conditions originating with water in the fuel contributed to creating extreme cylinder pressures far exceeding those foreseen by the LF9 engine designers. These pressures would damage the head gasket and sometimes break head bolts.

A head gasket leak effectively quenched ignition in the affected cylinder. This allowed unburnt fuel and coolant to leak into the crankcase, and would thin the lubricating oil. It also combined with combustion byproducts to make mild acids that attacked the copper/babbitt bearings and aluminum pistons. A head gasket failure can be particularly damaging in a diesel. A diesel engine has effectively no piston to head clearance at TDC on the compression stroke. The introduction of coolant into the cylinders can cause hydrolock. Hydrolock typically results in bent/broken crankshafts, pulled threads on main bolts, and bent connecting rods, effectively destroying an engine.

Because the various failures these engines encountered were causally interrelated, and dealership technicians were unfamiliar at best with passenger car diesel engines, recurrent failures were possible because only the most obvious symptoms of trouble were addressed. The "one use only" head bolts were commonly re-used and symptoms in other interrelated systems ignored. Thus, cars could suffer multiple head gasket/head bolt failures from re-use of head bolts or a damaged injection system.

The Oldsmobile Diesel V6 engines, although sharing much of the same production history, were produced on different tooling, where it was feasible to upgrade the head bolt pattern to what is arguably a superior design capable of withstanding more consumer abuse. However, the fuel system suffered from the same deficiencies.


The 455 "big block" Olds V8 was replaced in 1977 with the 403 cu in (6.6 L) "small block" V8. It used a wide 4.351 in (110.5 mm) bore, the largest ever used in a small-block V8, with the Olds small-block standard deck and 3.385 in (86.0 mm) stroke. The bore was so wide that the cylinder walls were "siamesed" (similar to another GM 400 CID small block engine) — there was no space for coolant flow between the cylinders. This sometimes led to overheating problems. Some very early 403s were painted metallic blue like the 455, but most were painted GM Corporate Blue.

The Olds 403 was used by Buick and Pontiac in addition to Oldsmobile. The engine was only produced through 1979. Output was 185 hp (138 kW) and 320 lb·ft (430 N·m).



A smaller 260 cu in (4 l) V8 was produced in 1975 by decreasing the bore to just 3.5 in (89 mm). This was the first powerplant to use the smaller Rochester Dualjet two-barrel carburetor; all 260s used it. Production of the 260 V8 ended in 1982 when the 307 became the only gasoline V8 in Oldsmobile's line.

The 260 was designed for economy and it was the first engine option above the 3.8L Buick V6 standard in many Oldsmobile models by the late 1970s. While the 260s were not very powerful compared to the larger 350 and 403 V8s, fuel economy was almost as good as the base V6. Compared to the V6, the 260 was also smoother-running, and far more durable.

Most 260s were coupled to the Turbo Hydramatic 200. A 5-speed manual transmission was also available with some 260-equipped vehicles.



The LV8 was a 260 cu in (4.3 L) version produced from 1975-1982. It produced just 105 hp (78 kW) and 205 lb·ft (278 N·m).

LF7 Diesel

The LF7 was a 260 cu in (4.3 L) Diesel V8 putting out 90 hp (67 kW) and 160 ft·lbf (220 N·m) torque. It was only used in 1979 as it did not meet 1980 emissions requirements.



A slightly larger 307 cu in (5.0 L) version was introduced in 1980. It uses a 3.8 in (97 mm) bore (in common with the Buick 231 V6 and 350 V8) with a 3.385 in (86.0 mm) stroke. Some early 307s were painted GM Corporate blue, but most were painted satin black. It was used in most Oldsmobile models, as well as those from Buick, Cadillac, Chevrolet, and Pontiac. Every 307 used a four-barrel carburetor, generally a variant of the Rochester Quadrajet, usually the CCC (Computer Command Control) Quadrajet.

In fact, the 1990 5.0 L Olds V8 was the last carbureted passenger car engine on the market in the U.S. (excluding the 1991 Ford LTD Crown Victoria Police Interceptor 351 cu in (5.8 L) V8, the 1991 Subaru Justy (base model) and the 1993 Isuzu pick up truck, the very last carbureted road vehicle sold in the U.S.).

The output of the 307 cu in (5.0 L) was not particularly high in terms of horsepower. For example, the stock (non-high-output, VIN "Y") 307 cu in (5.0 L) in the 1983 Oldsmobile 98 was a mere 140 hp (100 kW), although in that year a high-output model (VIN "9") was available producing a nominal 180 hp (130 kW), at approximately 245 lb·ft (332 N·m) torque. The final 1990 configuration was rated at 140 hp (100 kW) at 3200 rpm and 255 lb·ft (346 N·m) of torque at 2000 rpm. The combination of good low-RPM torque, the Quadrajet four-barrel carburetor, and the THM-200-4R three speed plus overdrive automatic transmission having a lockup torque converter allowed for fairly good performance, and fuel economy considered reasonable for the era, even in the larger and heavier model cars.



Oldsmobile used the popular LV2, a 307-cubic-inch (5.0 L) engine, commonly known by the VIN code "Y", from 1980-1990. It was used by every domestic GM automobile marque. Roller lifters, floating piston wrist pins, and swirl port intake runners were added in 1985.

The 307 "Y" produced 148 hp (110 kW) and 250 lb·ft (340 N·m) in 1980-1984 models and 140 hp (100 kW) and 250 lb·ft (340 N·m) in 1985-1990s. All LV2s feature a 4-barrel carburetor.

Y-version applications:


The LG8 was a modern 307 cu in (5.0 L) High-Output derivative of the LV2 produced from 1983 to 1987. Performance modifications included a "hot" camshaft (in reality, just the base model 455 camshaft from the '70s with .440"/.440" lift and 196°/208° duration at .050"), stiffer valve springs, a larger vibration damper (same as all '73-'79 350s, 403s, and 455s), a Y-pipe dual-outlet exhaust system, and richer secondary metering rods in the carburetor. It was offered in the Hurst/Olds version of the Oldsmobile Cutlass Calais and in the 442 version of the Oldsmobile Cutlass Salon. Output for 1983-1985 was 180 hp (130 kW) and 245 lb·ft (332 N·m). Revisions to the engine for 1986 included roller lifters with a slightly smaller camshaft (.435"/.438" lift and 194°/210° duration at .050"), new heads with smaller, swirl-port intake runners, floating piston pins, and larger piston dishes for lower compression (8.0:1 v. 8.4:1). These changes increased torque to 250 lb·ft (340 N·m) but lowered power to 170 hp (130 kW), while lowering the RPM at which peak power and torque was achieved.


Generation 3

The GenII Oldsmobile V8 ended production in 1990. The company later introduced a new vehicle, the Oldsmobile Aurora, with a new generation of V8 power. Based on the Cadillac Northstar engine, the Oldsmobile Aurora engine was a DOHC design.

See also

From the 1950s through the late 1970s, each GM division had its own V8 engine family. Many were shared among other divisions, but each design was unique:

GM later standardized on the later generations of the Chevrolet design:

External links


  1. ^ Hot Rod, 3/86, p.54.
  2. ^ Hot Rod, 3/86, p.54.
  3. ^ Hot Rod, 3/86, p.54.
  4. ^ Hot Rod, 3/86, p.54.
  5. ^ Hot Rod, 3/86, p.54.
  6. ^ Flory, J. "Kelly", Jr. American Cars 1946-1959 (Jefferson, NC: McFarland & Coy, 2008), p.833.
  7. ^ Flory, J. "Kelly", Jr. American Cars 1960-1972 (Jefferson, NC: McFarland & Coy, 2004), p.118.
  8. ^ Flory, American Cars 1946-1959 p.833.
  9. ^ Flory, American Cars 1946-1959, p.834.
  10. ^ The optional heater-defroster cost $85 that year, the optional base radio $96. Flory, American Cars 1946-1959, p.834.
  11. ^ Flory, American Cars 1946-1959, p.990.
  12. ^ Depending on carburetion or use of turbocharger. Flory, J. "Kelly", Jr. American Cars 1960-1972 (Jefferson, NC: McFarland & Coy, 2004), pp.205 & 246.
  13. ^ Baechtel, John. "Alternative Engines: Part 2--Buick V8", in Hot Rod Magazine, 11/84, p.67.
  14. ^ Baechtel, p.67.
  15. ^ Davis, Marlan. "Affordable Aluminum V8's [sic]", in Hot Rod Magazine, March 1985, pp.84-9 & 121.
  16. ^ Davis, p.87.
  17. ^ http://blogs.edmunds.com/karl/2007/06/talk-back-tuesday-every-diesel-has-or-will-have-its-day.html
  18. ^ http://www.theautochannel.com/news/writers/bhagin/1998/fs9845.html
  19. ^ http://www.gm-diesel.com/vbull/non-turbo-charged-diesels/20692-5-7-4-3-olds-diesel-faq-2.html#post154860

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