Chevrolet small-block engine

Chevrolet Small-Block V8 engine
Manufacturer:	General Motors
Production:	1955–2003
Successors:	GM LT engine, GM LS engine
Type:	small-block V8
265
Production:	1955–1957
Displacement:	265 cu in (4.3 L)
Power:	162 hp (121 kW)-240 hp (179 kW)
Bore and Stroke:	3.750 × 3.00 in (95.2 × 76.2 mm)
283
Production:	1957–1967
Displacement:	283 cu in (4.6 L)
Power:	195 hp (145 kW)-315 hp (235 kW)
Bore and Stroke:	3.875 × 3.00 in (98.4 × 76.2 mm)
327
Production:	1962–1969
Displacement:	327 cu in (5.4 L)
Power:	235 hp (175 kW)-375 hp (280 kW)
Bore and Stroke:	4.000 × 3.25 in (101.6 × 82.5 mm)
350
Production:	1967–2003
Displacement:	350 cu in (5.7 L)
Power:	145 hp (108 kW)-370 hp (276 kW)
Bore and Stroke:	4.000 × 3.48 in (101.6 × 88.4 mm)
302
Production:	1967–1969
Displacement:	302 cu in (4.9 L)
Power:	290 hp (216 kW)
Bore and Stroke:	4.000 × 3.00 in (101.6 × 76.2 mm)
307
Production:	1968–1973
Displacement:	307 cu in (5.0 L)
Power:	115 hp (86 kW)-200 hp (149 kW)
Bore and Stroke:	3.875 × 3.25 in (98.4 × 82.5 mm)
400
Production:	1970–1981
Displacement:	400 cu in (6.6 L)
Power:	150 hp (112 kW)-265 hp (198 kW)
Bore and Stroke:	4.125 × 3.75 in (104.8 × 95.2 mm)
262
Production:	1975–1976
Displacement:	262 cu in (4.3 L)
Power:	110 hp (82 kW)
Bore and Stroke:	3.670 × 3.10 in (93.2 × 78.7 mm)
305
Production:	1976–2000
Displacement:	305 cu in (5.0 L)
Power:	130 hp (97 kW)-250 hp (186 kW)
Bore and Stroke:	3.736 × 3.48 in (94.9 × 88.4 mm)

The Chevrolet small-block engine is a series of automobile V8 engines built by the Chevrolet Division of General Motors using the same basic small (for a V8) engine block. Retroactively referred to as the "Generation I" small-block, it is distinct from subsequent "Generation II" LT and "Generation III" LS engines.

Production of the original small-block began in 1955 with a displacement of 265 cu in (4.3 L), growing incrementally over time until reaching 400 cu in (6.6 L) in 1970. Several intermediate displacements appeared over the years, such as the 283 cu in (4.6 L) that was available with mechanical fuel injection, the 327 cu in (5.4 L) (5.3L), as well as the numerous 350 cu in (5.7 L) versions. Introduced as a performance engine in 1967, the 350 went on to be employed in both high- and low-output variants across the entire Chevrolet product line.

Although all four of Chevrolet's siblings of the period (Buick, Cadillac, Oldsmobile, and Pontiac) designed their own V8s, it was the Chevrolet 350 cu in (5.7 L) small-block that became the GM corporate standard. Over the years, every American General Motors division except Saturn used it and its descendants in their vehicles.

Finally superseded by GM's Generation II LT and Generation III LS V8s in the 1990s and discontinued in 2003, the engine is still made by a GM subsidiary in Mexico as an aftermarket replacement. In all, over 90,000,000 small-blocks have been built in carbureted and fuel injected forms since 1955.

The small-block family line was honored as one of the 10 Best Engines of the 20th Century by automotive magazine Ward's AutoWorld.^[1]

The Chevrolet 90-Degree V6 engine, which is still in production, is this original small-block (and NOT the newer LS1) but minus cylinders #3 and #6

Confusion with LT and LS engines

The original Chevrolet-designed small-block is a specific family of engines manufactured originally in 1955 and installed as production powerplants by GM for 48 years.

Subsequent GM small block V-8 engine designs built on different blocks are often confused with the original small-block.

• For more information on the Generation II small-block V8s, which differ mainly in their reverse-flow cooling system, see the GM LT engine.

• For more information on the current family of Chevy Generation III/IV General Motors small-block V8s see the GM LS engine.

Overview

The first generation of Chevrolet small-blocks began with the 1955 Chevrolet 265 cu in (4.3 L) V8 offered in the Corvette and Bel Air. Soon after being introduced, it quickly gained popularity among stock car racers, becoming known as the "Mighty Mouse" motor, after the popular cartoon character of the time, with the simpler "Mouse" nickname becoming much more popular as time went on.

By 1957 it had grown to 283 cu in (4.6 L). Fitted with the optional Rochester mechanical fuel injection, it became one of the first production engine ever to make one horsepower per cubic inch. The 283 would later be extended to other Chevrolet models, replacing the old style 265 V8s.

A high-performance 327 cu in (5.4 L) variant followed, turning out as much as 375 hp and increasing horsepower per cubic inch to 1.15.

It was, however, the 350 cu in (5.7 L) series that came to be the best known Chevrolet small block. The engine's oversquare 4.00-inch bore and 3.48-inch stroke (102 mm by 88 mm) are nearly identical to the 436 hp (325 kW) LS3 engine of today, but much has changed. Installed in everything from station wagons to sports cars, in commercial vehicles, and even in boats and (in highly modified form) airplanes, it is by far the most widely used small-block of all-time.

Though not offered in GM vehicles since 2004, the 350 cu in (5.7 L) series is still in production today at General Motors' Toluca, Mexico plant under the company's "Mr Goodwrench" brand, and is also manufactured as an industrial and marine engine by GM Powertrain under the Vortec name.

From 1955–74, the small-block engine was known as the "Turbo-Fire V8".

Small Block Chevrolet V8 (1955–1998)

The small-block made its debut in 1955 and remained popular for over five decades for its relatively compact size, light weight, and extensive aftermarket support. The engines have been placed into families with the name of each family being the bore size of that family’s progenitor.

3.750/3.875 in. bore family (1955–1973)

The engine family from which all Chevy V8s from the big blocks to today's LS7 and LS9 evolved is the 265/283 small block family. Of the three engines in this family, two of them, the 265 and the 283, have gone down in automotive history. The first of this family was the 265 in 1955. The 283, famous for being one of the first engines to make 1 hp per cubic inch is also famous for being the evolutionary stepping stone that would give rise to later small blocks and to the “W” blocks which would later give rise to the Chevy big blocks. The last of this family was the 307 which was a stroked 283 with a medium journal.

265

The 265 cu in (4.3 L) V8 was the first Chevrolet small block. Designed by Ed Cole's group at Chevrolet to provide a more powerful engine for the 1955 Corvette than the model's original "stove bolt" in-line six, the 165 hp (123 kW)^[2] 2-barrel debut version went from drawings to production in just 15 weeks.

A pushrod cast-iron engine with hydraulic lifters, the small block was available with an optional 4-barrel Rochester carburetor, increasing engine output to 195 hp (145 kW). The oversquare (3.75 in (95 mm) bore, 3 in (76 mm) stroke) engine's 4.4 in (111.8 mm) bore spacing would continue in use for decades.

Also available in the Bel Air sedan, the basic passenger car version produced 162 hp (121 kW) with a 2-barrel carburetor. Upgraded to a four-barrel Rochester, dual exhaust "Power Pack" version, the engine was conservatively rated at 180 hp (134 kW).

A shortcoming of the 1955 265 was that the engine had no provision for oil filtration built into the block, instead relying on an add-on filter mounted on the thermostat housing. In spite of its novel green sand foundry construction, the '55 block's lack of adequate oil filtration leaves it typically only desirable to period collectors.

The 1956 Corvette introduced three versions of this engine – 210 hp (157 kW) with a single 4-barrel carb, 225 hp (168 kW) with twin 4-barrels, and 240 hp (179 kW) with twin fours and a high-lift cam.

283

The 265 ci V-8 was bored out to 3.875 in (98.4 mm) in 1957, giving it a 283 cu in (4,638 cc) displacement. The first 283 motors used the stock 265 blocks. However, the overbore to these blocks resulted in thin cylinder walls. Future 283 blocks were recast to accept the 3.875 bore. Five different versions between 185 hp (138 kW) and 283 hp (211 kW) were available, depending on whether a single carb, twin carbs, or fuel injection was used. Fuel injection yielded the most power. Horse power was up a bit each year for 1958, 1959, and 1960. The 1957 Ramjet mechanical fuel injection version produced an even 1 hp per cubic inch (61 hp/L), an impressive feat at the time. Many thought this as the first US-built production V8 to produce one horsepower per cubic inch.

Besides being available in the Chevrolet line, it was optional in Checker Taxis beginning in 1965.^[3] A version of it that was built by GM Canada was also available in Studebakers produced in Canada for 1965 & 1966.

307

A 307 cu in (5,025 cc) version was produced from 1968 through 1973. Engine bore was 3.875 inches (98.4 mm) with a 3.25-inch (82.6 mm) stroke.

The 307—essentially a 283 block with the longer-stroke 327 crankshaft—replaced the 283 in Chevrolet cars in 1968, and produced 225 hp (149 kW) SAE gross at 4,600 rpm and 300 lb·ft (407 N·m) of torque at 2,400 rpm. This engine was an option in 1968 only Checker Marathons.^[4] Later versions produced as little as 115 hp (86 kW) SAE net. Chevrolet did not produce a high-performance version of the engine, but did produce, for Outboard Marine Corporation, a high-performance marinized 307, rated at 235 hp (175 kW) and 245 hp (183 kW) SAE gross, depending on year, that shipped with the Corvette/Z-28's cast aluminum valve covers and Rochester QuadraJet carb. Chevy also built other versions of the OMC 307 rated at 210 hp (157 kW), 215 hp (160 kW) and 225 hp (168 kW) SAE gross.

4.00 in bore family (1962–1998)

Originally intended as the performance block, this engine family through the 350 CID became an all purpose engine that saw use in many applications from Corvettes to vans. All engines in this family share the same block dimensions and sometimes even the same casting number; the latter meaning engines were of the same block, but with different strokes (e.g. the casting number 3970010 was used by all three engines: 302, 327, and 350). This engine family was updated in 1968 for the use of 2.45” medium-sized journals. The first engine in this family was the small journal 327 in 1962 and the last being 1992's medium journal 350. The medium journal 350 would later be further developed into the "Generation II" LT 350 in the early 1990s.

302

Chevrolet produced a special 302 cu in (4.9 L) (referred to as 5.0 L) engine for Sports Car Club of America SCCA Trans-Am Series racing from 1967–1969. It was the product of placing the 283 3-inch stroke crankshaft into a 4-inch bore 327 block. The 1967 302 used the same nodular cast-iron crank as the 283[4], with a forged-steel crankshaft that was also produced. This block is one of 3 displacements, 302/327/350, that underwent a crankshaft bearing diameter transformation for 1968 when the rod-journal size was increased from the 2.00 in. diameter small-journal to a 2.10 large-journal and the main-journal size was increased from 2.30 in. to 2.45. The large-journal connecting rods were heavier and used 3/8 in. diameter cap-bolts to replace the small-journal’s 11/32. 1968 blocks were made in 2-bolt and 4-bolt versions with the 4-bolt center-three main caps each fastened by two additional bolts which were supported by the addition of heavier crankcase main-web bulkheads. When the journal size increased to the standard large-journal size, the crankshaft for the 302 was specially built of tufftride-hardened forged 1053-steel and fitted with a high-rpm 8.00 in. diameter harmonic balancer. This engine was used only in the first-generation (1967-69) Z/28 Camaro. It had a 3/4-length semi-circular windage tray, heat-treated, magnafluxed, and shot-peened forged 1038-steel 'pink' connecting rods, floating-pin in `69, and forged-aluminum pistons with higher scuff-resistance, better sealing single-moly rings. Its solid-lifter cam, known as the '30-30 Duntov' named after its .030/.030 in. intake/exhaust hot valve-lash and Zora Arkus-Duntov the "father of the Corvette", was also used in the 1964-65 carbureted 327/365 and F.I. 327/375 engines. It used the '202' 2.02/1.60 valve diameter high-performance 327 double-hump #461 heads, hardened 'blue-stripe' pushrods, edge-orifice lifters to keep more valvetrain oil in the crankcase for high-rpm lubrication, and stiffer valvesprings. In 1967, a new design high-rise cast-aluminum dual-plane intake manifold with larger runners and smoother passage turns was introduced for the Z/28 that the LT-1 350 1969 Corvette and 1970 Z/28 were equipped with until 1973. Unlike the Corvette, the exhaust manifolds were the more restrictive rear outlet 'log' design to clear the Camaro's front cross-member. It had a chrome oil filler tube and valve covers from 1967 to 1968, and chrome 14.00 x 3.00 in. drop-base open-element air-cleaner assembly on a 780cfm vacuum secondary Holley 4-Bbl carburetor. A 'divorced' exhaust crossover port heated well-choke thermostat coil was used to provide cleaner and faster engine warm-up. Its single-point distributor had an ignition point cam designed to reduce point-bounce at high-rpm along with a vacuum diaphragm to advance ignition timing at idle and part-throttle for economy and emissions. Balancer and water-pump pulleys, as well as optional power-steering's pulley, were deep-groove for belt retention at high-rpm. In 1969, the 302 shared the cast-aluminum valve covers with the LT-1 350 Corvette engine. Conservatively rated at 290 hp (216 kW) (SAE gross) at 5800 rpm and 290 lb-ft at 4800, actual output with its production 11:1 compression ratio was around 376 hp (280 kW) with tubular headers that came in the trunk when ordered with a new Z/28, carburetor main-jet, and ignition timing tuning.

After the 1967 Trans-Am campaign with the 4-Bbl induction system producing more horsepower than the competing auto makers' 8-Bbl systems, for 1968 Chevrolet developed a factory 'cross-ram' aluminum intake-manifold package using two Holley 585cfm mechanical-secondary carburetors for Trans-Am racing. It was available only as off-road service parts purchased over the Chevrolet dealership parts counter. With the Chevrolet '140' off-road cam, the package increased a stock 302's hp from 360 hp to approximately 400. Chevrolet went so far as to carry the positive crankcase ventilation (PCV) system over to the cross-ram induction system to retain emissions compliance mandated for U.S.-produced cars beginning in 1967, that also provided full-throttle crankcase pressure venting to the intake air to burn its vapors. Engines prepared for competition use were capable of producing 465 hp with little more than the 8-Bbl induction, ported heads with higher pressure valvesprings, roller rocker arms, and the '754' road-race cam. 1967/1968 models' cowl-induction system had an enclosed air-cleaner assembly ducted from its passenger side into the firewall cowl above the heater core. In 1969, factory ZL-2 cowl-induction hoods were available for both the single and dual four-barrel induction systems that were sealed to the air-cleaner base ensuring cooler, high-pressure, dense air from the center of the base of the windshield was supplied to the engine for combustion smoothness and maximum power production. Another popular service-parts-only component used on the 302 was the Delco transistor-ignition distributor, introduced in 1967 and also used in the L88 427 Corvette, that eliminated the production breaker-point ignition allowing more stable ignition-timing at high engine speeds.

The 302's bore/stroke and rod/stroke geometries made it a natural high-rpm engine and were responsible for its being among the more reliable production street engines homologated for full-competition across all the American makes winning back-to-back Trans-Am Championships at the hands of Mark Donohue in 1968 and 1969. However, the pinnacle of the 302's use in professional racing was its being the primary engine that powered the outstanding but overshadowed 1967-1976 SCCA Formula 5000 Championship Series, a SCCA Formula A open-wheel class designed for lower cost. Weighing 1400 lbs., with 525-550 hp, a 5-spd. transaxle, and 20 in. wide 15 in. rear wheels, it produced incredibly exciting racing. Prepared with a Lucas-McKay mechanically-timed fuel-injection, individual-stack magnesium induction-system that was paired with ported production double-hump iron heads and a virtually stock production crankshaft, it had a lasting impact on the series' ability to conduct high car-number finishes and close competition events by the degree of mechanical success it provided to a series filled with star international Grand Prix drivers like, David Hobbs, Brian Redman, Jody Scheckter, and Mario Andretti.

327

The 327 cu in (5,354 cc) V8, introduced in 1962, had a bore of 4 in (101.6 mm) and a stroke of 3.25 in (82.55 mm). Power ranged from 210 hp (157 kW) L30 to 375 hp (280 kW) depending on the choice of carburetor or fuel injection, camshaft, cylinder heads, pistons and intake manifold. In 1962, the Duntov solid lifter cam versions produced 340 hp (254 kW), 344 lb·ft (466 N·m) with single Carter 4-barrel, and 360 hp (268 kW), 352 lb·ft (477 N·m) with Rochester mechanical fuel injection. In 1964, horsepower increased to 365 hp (272 kW) for the now dubbed L-79 version, and 375 hp (280 kW) for the fuel injected L-84 respectively, making the L-84 the most powerful naturally aspirated, single-cam, production small block V8 (aside from the limited-run Ford Boss 351) until the appearance of the 385 hp (287 kW), 385 lb·ft (522 N·m) Generation III LS6 in 2001. This block is one of three displacements that underwent a major change in 1968/1969 when the main journal size was increased from 2.30 inches (58.4 mm) to 2.45 inches (62.2 mm).

In 1966, Checker began offering the 327 as an option.^[5]

350

The 350 first appeared as a high-performance 295 hp L-48 option for the 1967 Chevrolet Camaro. One year later it was made available in the Chevrolet Nova, and finally in 1969 the rest of the Chevrolet line could be ordered with a 350. Many variants followed:

• L-48

Years: 1967–1980

The L-48 is the original 350 cu in (5.7 L), available only in the Camaro (1967-up) or Chevy II/Nova in '68-79. In '69 it was used in almost all car lines; Camaros, Impalas, El Caminos, Chevelles & Novas. 1969 L-48's use a Hyd Cam, 4bbl Quadrajet carburetor, cast pistons, 4-bolt main #010 Blocks & #041 or 186 heads. Power output was 300HP and 380 lb·ft (520 N·m) torque. Compression ratio was 10.25-1. In 1972 the only way to get a L-48 (4bbl V8) in a Chevy Nova was to get the Super Sport Package. This is indicated by the 5th digit in the VIN being a "K". 1972 was the only year you could verify the Super Sport package by the VIN.

The L-48 V8 was the standard engine in the 1975–1980 Chevrolet Corvette. The L-48 V8 Corvette engine produced 165 bhp in 1975. Power increased to 180 bhp in 1976 and stayed the same in 1977. 1978 saw 175 bhp for California or high altitude areas and 185 bhp for everywhere else. Power increased to 195 bhp in 1979 and decreased to 190 bhp in 1980.^[6]

• ZQ3

Years: 1970-1974 The ZQ3 was the standard engine in the 1970–1974 Chevrolet Corvette. It was a 300 bhp version of the 350 cu in small-block, with 10.25:1 compression and hydraulic lifters. It used a Rochester "4MV" Quadra-Jet 4-barrel carburetor.^[7] This was the first block produced that featured the larger 2.45 inch main bearing versus the older 2.30 inch main bearing in 1968/1969.

• note* post 1971 blocks had a lower nickel content but thicker cylinder deck, and post 1974 heads of the small block chevy used less iron in them and are lighter weight, and less powerful because of the lower compression ratios used.

In 1971, power decreased to 270(gross)bhp and 300(gross)lb-ft of torque with 8.5:1 compression. 1972 saw 200(net)bhp and 270(net)lb-ft of torque. In 1973 power decreased to 190 bhp, but increased slightly in 1974 to 195 bhp.^[6]

• L46

Years: 1969 The L46 was an optional engine for the 1969 Chevrolet Corvette. It was a higher performance version of the base 350 cu in V8 with #492 LT-1 "2.02" 2.02/1.60 valve heads and had a 11:1 compression ratio and produced 350 bhp.^[6]

• LT-1

LT-1 from a 1970 Chevrolet Camaro Z28

Years: 1970–1972

The LT-1 was the ultimate 350 cu in V8, becoming available in 1970. It used solid lifters, 11:1 compression, the '178' high-performance camshaft, and a 780 CFM Holley four-barrel carburetor on a special aluminum intake, with rams' horn exhaust manifolds in the Chevrolet Corvette, Delco transistor ignition and a low-restriction exhaust to produce a factory rated 370 bhp at 6000 rpm and 380 lb-ft at 4000^[8] (the NHRA rated it at 425 hp for classification purposes). Redline was 6500 rpm but power fell off significantly past 6200 rpm. The LT-1 was available in the Corvette, Corvette ZR-1, and Camaro Z28. Power was down in 1971 to 330 bhp and 360 lb-ft of torque with 9:1 compression, and again in 1972 (the last year of the LT-1, now rated using net, rather than gross, measurement) to 255 bhp and 280 lb-ft.

The "LT1" designation was later reused on a Generation II GM engine, the LT1.

• L82

Years: 1973–1980

The 1973–1974 L82 was a "performance" version of the 350 that still used the #624 76cc chamber LT-1 "2.02" heads but with a Rochester Quadra-jet 4-Bbl carburetor and dual-plane aluminum intake manifold, an updated version of the 350hp 327 hydraulic-lifter cam, and 9:1 compression forged-aluminum pistons producing 250 bhp (`73 was the first year for SAE net hp rating, as installed in the vehicle with accessories and mufflers) and 285 lb-ft of torque. Its cast-aluminum LT-1 valvecovers were painted crinkle-black contrasting with the aluminum manifold and distributor housing. It was down to 205 bhp and 255 lb-ft of torque for 1975. It produced 210 bhp in the Corvette for 1976-1977. The 1978 L82 recovered somewhat, producing 220bhp and 260lb-ft in the Corvette and in 1979 it produced 225 bhp in the Corvette. In 1980, its final year, it produced a peak of 230 bhp.^[6] This engine was also available on the Chevrolet Camaro.

• L81

Years: 1981

The L81 was the only 5.7 L (350 cu in) Corvette engine for 1981. It produced 190 bhp and 280 lb-ft of torque from 8.2:1 compression, exactly the same as the 1980 L48, but added computer control spark advance, replacing the vacuum advance^[9]

• L83

Years: 1982, 1984

The 1982 L83 was again the only Corvette engine (and only available with an automatic transmission) producing 200 bhp and 285 lb-ft of torque from 9:1 compression. This was again the only engine on the new 1984 Vette, at 205 bhp and 290 lb-ft of torque. The L83 added Cross-Fire fuel injection (twin throttle-body fuel injection). Since GM did not assign a 1983 model year to production Corvettes, there was also no L83 for 1983.^[6]

• L98

For the new Generation IV V8, see GM L98.

Years: 1985–1992

The new 1985 L98 added tuned-port fuel injection "TPI", which was standard on all 1985–1991 Corvettes. It was rated at 230 bhp for 1985-1986, 240 bhp for 1987-1990 (245 bhp with 3.07:1 rear axle ratio (1988-1990 only)), and 245 bhp in 1991 (250 bhp with 3.07:1 rear axle). Aluminum cylinder heads (Corvette only) were released part way through the 1986 model run and continued through the end of L98 Corvette production in 1991.^[10] The L98 V8 was optional on 87–92 Chevrolet Camaro & Pontiac Firebird models (rated at 225 hp (168 kW)-245 hp (183 kW) and 330 lb·ft (447 N·m)-345 lb·ft (468 N·m)) 1987 versions had 10 hp (7 kW) and 15 lb·ft (20 N·m) more thanks to 9.5:1 compression and a change to hydraulic roller camshaft. Compression was up again in 1991 to 10:1 but output stayed the same.

• LM1

The LM1 is the base 5.7 L (350 cu in) with a 4-barrel carburetor (usually with a Rochester Quadrajet) in passenger cars until 1988. Throughout its lifespan, it received either a points, electronic, and/or computer-controlled spark system, to conventional and feedback carburetors.

LM1s were superseded with the L05 powerplant after 1988.

• L05

The L05 was introduced in 1987 for use in Chevrolet/GMC trucks in both the GMT400 (introduced in April 1987 as 1988 models) and the R/V series trucks such as the K5 Blazer, Suburban, and rounded-era pickups formerly classed as the C/K until 1991 which includes chassis cabs and 4-door crew cabs. Although usage was for trucks, vans, and 9C1-optioned Caprices, the L05 was also used with the following vehicles:

• 1992/1993 Buick Roadmaster sedan and station wagon
• 1990–1992 Cadillac Brougham (optional engine)
• 1993 Cadillac Fleetwood
• 1989-1993 Chevrolet Caprice 1A2-optioned special service station wagon
• 1992/1993 Chevrolet Caprice Wagon (optional engine)
• 1993 Chevrolet Caprice LTZ
• 1992 Oldsmobile Custom Cruiser Wagon (optional engine)

L05 usage was replaced by the LT1 after 1993 in GM B-Bodies until production ceased in 1996.

In mid 1996 the L05 was equipped with Vortec heads used in the 1996 G30.

• L31

The L31 replaced the L05 in 1996 – known as the Vortec 5700. The Vortec 5700 produces 255 hp (191 kW) to 350 hp (261 kW) at 4600 rpm and 330 ft-lbf (448 N·m) to 350 ft-lbf (475 N·m) of torque at 2800 rpm. Known as the GEN 1+, this was the final incarnation of the 1955-vintage small block, ending production in 2005 with the last vehicle being a Kodiak/Topkick HD truck. Volvo Penta and Mercury Marine still produces the L31. The "MARINE" intake is a potential upgrade for L31 trucks. Using this "MARINE" intake will allow the use of common types of injectors with various flow rates while still maintaining emission compliance.

• Goodwrench

The GM Goodwrench 350 crate engine comes in several variations. The cheapest version produces 195 net horsepower (with accessories), and 260 gross horsepower (without the alternator, power steering, A/C compressor, catalytic converter, factory exhaust manifold, and muffler) when used with a four barrel carburetor, dual exhaust, and headers. The low output is the result of the relatively low 8.5:1 compression ratio, restrictive cylinder heads, dished pistons, and stock camshaft profile.^{[citation needed]}

All of the GM Goodwrench engines use the pre-1986 four-bolt casting molds with two dipstick locations; pre-1980 on the driver's side and post-1980 on the passenger's side. This engine was produced in Mexico since 1981 as the Targetmaster 350, and now the GM Goodwrench 350.^{[citation needed]}

The 350 can be turned into a 383 stroker or a 355. The 383 can be made by purchasing a kit that comes with everything that is needed except machine work. The cylinders should also be bored .030 over. The 383 has a bore of 4.030 and a stroke of 3.75 inches.The 355 can be made by just boring the block .030 over and using the stock 350 crank. The 355 has a bore of 4.030 and a stock stroke of 3.48 inches.

4.125 in bore family (1970–1980)

400

The only block of this family, 400 cu in (6.6 L) small-block, was introduced in 1970 and produced for 10 years. It was loosely based on the medium journal 350 and had a 4.125-inch (104.8 mm) bore and a 3.75-inch (95.3 mm) stroke. The 400 differed from other small blocks in that the cylinders were siamesed, used a 2.65” large journal, and oftentimes had one more freeze plug on both the left and right sides of the block. Initial output was 265 hp (198 kW) and was only available equipped with a 2-barrel carburetor. In 1974 a 4-barrel version of the 400 was introduced, while the 2-barrel version stopped production in 1975. 1976 was the last year that the 400 was used in a Chevrolet Passenger car, available in both A-Body and B-Body lines. While popular with circle-track racers and drag racers, the engine was prone to cooling problems if cylinder heads without steam holes were used.

3.671 in bore family (1975–2003)

Designed and built during the era of the gas embargo and tighter emissions, this engine family was meant as “economy” V8’s. This family through the 305 became an all purpose engine that was intended to have better gas economy than the larger 350 but more power and torque than GM's contemporary line of inline 6 cylinders. During the 80’s when GM was streamlining their engine lineups, the 305 rose to prominence as Chevrolet’s “Corporate” engine, signifying its use in multiple GM brands. Through much of the 80’s the 305 became an alternative to the 350 as the least poorly-performing engine in the F body cars and even made an appearance in the Corvette for one year in 1980. The first engine in this family was the medium journal 262 in 1975, and the last the medium journal 305. The medium journal 305 would later on, like its contemporary 350, in the early 1990s be further developed- although with a reduced stroke- into the "Generation II" LT L99 263.

262

The 1975–1976 262 was a 262 cu in (4.3 L) 90° pushrod V8 with an iron block and heads. Bore and stroke were 3.67 in (93 mm) by 3.10 in (78.7 mm). Power output for 1975 was 110 hp (82 kW) and 195 lb·ft (264 N·m) at 3600 rpm. The 262 was replaced by the 305 for the 1977 model year.

This was Chevrolet's second 4.3 L-displacement powerplant; three other Chevrolet engines displaced 4.3 L: the Vortec 4300 (a V6 based on the Chevrolet 350, with two cylinders removed), the original 265 V8 in 1955, and a derivative of the GenerationII LT engines known as the L99 (using the 305's 3.736-inch bore, 5.94-inch connecting rods, and a 3-inch crankshaft stroke).

This engine was used in the following cars:

• 1975–1976 Chevrolet Monza
• 1975 Chevrolet Nova
• Early 1977 Pontiac Ventura

305

The 305 5.0L variant of the small-block Chevrolet which was a 262 that was bored out and stroked using the crank of the 350 was introduced in 1975 had a displacement of 305 cu in (5.0 L) with a 3.7350-inch (94.869 mm) bore, and 3.4803-inch (88.4 mm) stroke. Many performance enthusiasts shun the 305 because of the wide availability of 350 engines, along with the fact that the same parts will yield much more power in a 350 cubic inch package. Due to the popularity of the 350, items like rebuild kits are more expensive for the 305. The 305 still has power potential due to the broad selection of aftermarket parts that are readily interchangeable with the popular 350. Not all cylinder heads may be adapted to this engine due to valves having bore interference or shrouding issues with the narrow bore of the 305 engine, but there are many LO3 setups that can produce over 300 horsepower from the right combination.

Induction systems for the 305 included carburetors (both 2 and 4-barrel), throttle-body injection (TBI), tuned-port fuel injection (TPI), and sequential fuel injection (GM Vortec).

The 305 was used in the following cars:

• 1976–1992 Chevrolet Camaro
• 1980 Chevrolet Corvette (California only)
• 1977–1993 Chevrolet Caprice (includes Impala)
• 1977–1986 Pontiac Parisienne
• 1976–1979 Chevrolet Monza
• 1976–1979 Chevrolet Nova (also GM X-body clones after 1976)
• 1976–1988 Chevrolet Malibu, Chevrolet El Camino, and Chevrolet Monte Carlo
• 1978–1992 Pontiac Firebird
• 1978–1980 Oldsmobile Cutlass (US Market only, Canadian market 1978–1987)
• 1991–1992 Oldsmobile Custom Cruiser
• 1981–1987 Pontiac Grand Prix
• 1975–1979 Buick Skylark
• 1977–2003 Chevrolet/GMC Trucks, SUVs, Vans
• 1991–1992 Cadillac Brougham
• 1978–1987 Buick Regal

After 1996, its usage was limited to light trucks and SUVs until the 2000 model year (vans and commercial vehicles until 2003) as the Vortec 5000. Currently still in production as a marine powerplant for Mercury Marine.

Year	hp (kW)	lb•ft (N•m)
1976	140	250	w/2bbl.
1977	145	245	w/2bbl.
1978	140	240	w/2bbl.
1978	160	235	w/4bbl.
1979	130	245	w/2bbl.
1979†	125	235	w/2bbl.
1980	155	240	w/4bbl.
1981	150	240	w/4bbl

† California Emissions

• LG3

Years:1976–1980

This variant used a Rochester 2GC carburetor for 1976–78. In 1979 the more fuel efficient Dualjet 2-bbl carburetor replaced the older 2GC. This change also resulted in a drop in the horsepower rating to 130 hp (125 for California emissions cars). All years had an 8.5:1 compression ratio.

• LG4

Years: 1980–1987

The LG4 produced 150 hp (112 kW)-170 hp (127 kW) and 240 lb·ft (325 N·m)-250 lb·ft (339 N·m). The addition of a knock sensor for the engine management system in 1985 allowed an increase in compression and a more aggressive spark timing map in the ECM. As a result power increased for the 1985 models to 165 hp (123 kW) from the 150 hp (112 kW) rating in 1984.

• L69

Years: 1983–1986

The L69 featured a compression ratio of 9.5:1, heads from the LU5 engine and the camshaft from the L83. Additionally the engine came equipped with a dual snorkel air cleaner assembly, aluminum intake manifold, aluminum flywheel and a knock sensor which allowed more aggressive spark timing. This engine produced 190 hp (142 kW) @ 4800 and 240 lb·ft (325 N·m) of torque @ 3200 rpm.

• LE9

Years: 1981–1986

The LE9 5.0 L (305 cu in) was a truck/van/car version 4BBL 650CFM that also had a 9.5:1 compression ratio, the LM1 cam and 14010201 casting heads featuring 1.84/1.50" valves and 53 cc chambers. The engine made 210 hp (157 kW) @ 4,000 and 250 lb·ft (339 N·m) @ 2,000 rpm. NOTE, while it is 5.0 liters, the body is a 5.7 liter 350, the difference is in relation to the camshaft with respect to the diameter of their cylinders,and the 4 bolts in 350 vs to 2 in 305,being the last designs carburetor.

• LB9

Years: 1985–1992

The LB9 was introduced with 215 hp (160 kW) and 275 lb·ft (373 N·m) and varied between 190 hp (142 kW)-230 hp (172 kW) (with 275 lb·ft (373 N·m)-300 lb·ft (407 N·m) of torque) over the years offered.

• LO3

Years: 1987–95

The LO3 produced 170 hp and 255 lb·ft (346 N·m) of torque; 170 hp at 4,400 rpm and 275 lb·ft (373 N·m) at 2,400 in 1993–1995 GM trucks. This engine used throttle-body fuel injection.

3.50 in bore family (1979–1982)

267

The 267 was introduced in 1979 for GM F-Body (Camaro), G-bodies (Chevrolet Monte Carlo, El Camino, and Malibu Classic) and also used on GM B-body cars (Impala and Caprice models). The 268 cu in (4,390 cc) engine had the 350's crankshaft stroke of 3.48" and the smallest bore of any small-block, 3.500 in (88.9 x 88.4 mm). The 3½ in bore was also used on the 200 cu in (3.3 L) V6, which was introduced a year earlier. (The 200 was a Chevrolet V6 engine based on the small block with the #3 and #6 cylinders removed).

It was available with a Rochester Dualjet 210 – effectively a Rochester Quadrajet with no rear barrels. After 1980, electronic feedback carburetion was used on the 267. The 267 also saw use in 1980 to 1982 Checker Marathons.^[11]

While similar in displacement to the other 4.3–4.4 L V8 engines produced by General Motors (including the Oldsmobile 260 and Pontiac 265, the small bore 267 shared no parts with the other engines and was phased out after the 1982 model year due to inability to conform to emission standards. Chevrolet vehicles eventually used the 305 cu in (5.0 L) as its base V8 engine.

Major changes

The original design of the small block remained remarkably unchanged for its production run, which began in 1955 and ended, in passenger vehicles, in 2003. The engine is still being built today for many aftermarket applications, both to replace worn-out older engines and also by many builders as high-performance applications. The principal changes to it over the years include:

• 1956 – Full flow oil filtration was introduced, using a paper element filter in a canister that was mounted to a feature that was added to the cylinder block casting and machined for this purpose.
• 1957 – The displacement of the base V8 continued at 265 cubic inches but optional V8s were introduced with 283 cubic inch displacement.
• 1958 – Bosses for side motor mounts were added to the block casting and utilized for production mounts for this and all future model years. However the features for front motor mounts as used in 1955–1957 remained part of the block casting in this and future years. The 265 cubic inch version of the engine was discontinued.
• 1962 – The block's cylinder wall casting was revised to allow four inch bores and the 327 cubic inch version of the engine using this bore diameter and increased crankshaft stroke was introduced.
• 1968 – The main journal diameter was increased to 2.45 in (medium) from 2.30 in (small) and the connecting rod journal diameter was increased to 2.10 in from 2.00 in. This allowed the use of cast iron crankshafts as the previous parts were made of forged steel. The rod bolts were changed from 11/32 in. diameter to 3/8 inch. Additionally, the canister/sock style oil filter was now converted to use spin on filters. The oil fill location was moved from a tube on the front of the intake manifold to a cap on either side valve cover.
• 1986 – The rear main seal was changed from a 2-piece rubber design to a 1-piece rubber design that used a mounting appliance to hold it in place. This necessitated a change in the flywheel/flexplate bolt pattern, as well as the need for an externally balanced flexplate/flywheel.
• 1987 – The valve cover surfaces were changed such that cylinder head mounting lip was raised and the bolt location was moved from 4 bolts on the perimeter, to 4 bolts down the centerline of the valve cover (this design debuted on the Corvette in 1986, and Chevrolet 4.3 L the year before). Also changed were the mounting angles of the center 2 bolts on each side of the intake manifold (from 90 degrees to 73 degrees) and the lifter bosses were increased in height to accept roller lifters. The alloy heads for use in the Corvette still retain the non-angled bolts (center 2 bolts attaching to the intake). Also all carburetors were done away with and replaced by TBI (throttle-body injection) fuel injection on the Camaro & Firebird.
• 1996 – This was the last change for the Generation I engine, and continued through the end of the production run in 2003; all 1997–2003 Generation I engines were Vortec truck engines. The cylinder heads were redesigned using improved ports and combustion chambers similar to those in the Generation II LT1, resulting in significant power increases. The intake manifold bolt pattern was also changed to four bolts per cylinder head instead of the traditional six.

See also

• Buick V8 engine
• Cadillac V8 engine
• Oldsmobile V8 engine
• Pontiac V8 engine
• Chevrolet Big-Block engine
• GM LT engine – Generation II small block
• GM LS engine – Generation III/IV small block
• Chevrolet 90-Degree V6 engine - a V6 version of the original small-block removing cylinders 3 and 6, still in production
• List of GM engines

References

• McGuire, Bill (June 20, 2005). "Horsepower Nation: Chevrolet's small-block V8 celebrates its 50th birthday". AutoWeek. http://www.autoweek.com/article/20050620/FREE/506200719. Retrieved June 15, 2005. 

1. ^ Sherman, Dan (January 1, 2000). "The 10 Best Engines of the 20th Century". Ward's AutoWorld. http://wardsautoworld.com/ar/auto_best_engines_th/index.html. 
2. ^ "Chevy Corvette 1955 Technical Specifications". Unique Cars and Parts. http://www.uniquecarsandparts.com.au/chevy_corvette_1955_technical_specifications.htm. 
3. ^ Flory, J. "Kelly", Jr. American Cars 1960–1972 (Jefferson, NC: McFarland & Coy, 2004), p.341.
4. ^ Ron Kowalke, ed (1999). Standard Catalog of Independents: The Struggle to Survive Among Giants. Iola, WI: Krause Publications, Inc.. p. 36. ISBN 0-87341-569-8. 
5. ^ Flory, p.411.
6. ^ ^{a b c d e} Gunnell, John. Standard catalog of Corvette, 1953-2005. Krause Publications, 2004
7. ^ Gunnell, John. Standard Catalog of Corvette, 1953-2005. Krause Publications, 2004
8. ^ Gunnell, John, 360 bhp with the Camaro's 'log' manifold exhaust system and points ignition. Standard Catalog of Corvette, 1953-2005. Krause Publications, 2004
9. ^ Gunnell, John. Standard Catalog of Corvette, 1953-2005. Krause Publications, 2004
10. ^ Gunnell, John. Standard Catalog of Corvette, 1953-2005. Krause Publications, 2004
11. ^ Standard Catalog of Independents, pp. 41-42