HISTORY: 350 / 5.7

[] 350 / 5.7L

4.001 in Bore

3.48 in Stroke

350 CID 1967 – Present

 The 350, with a 3.48-inch stroke, first appeared as a high-performance 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. The engine was also exported to Australia where it appeared in the Holden Monaro from 1969 through 1972.

Engine Variant:

 L46

 1969 - 1970

 L48

 1967 - 1980

 L65

 2bbl ver. LM1

 LM1

 1972 - 1988

 ZQ3

 1970 - 1974

 LT-1

 1970 - 1972

 L82

 1973 - 1980

 L81

 1981

 LT-9

 1981- 1986

 L83

 1982 & 1984

 L98

 1985 - 1992

 LO5

 1987 - 1996

 L31

 1996 - 2002

 

[] L46

Years: 1969-1970

 The L46 became an optional engine for the 1969 Chevrolet Corvette. It was a higher performance version of the base 350 cu in V8 with casting number 492 2.02"/1.60" valve heads and had an 11:1 compression ratio (high octane gas must be used) and produced 350 bhp. It was also available in 1970. 4bbl Quadrajet carburetor and L46 hydraulic cam, dome piston (+2.6 cc), 186 heads, and a four-bolt block.

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[] L48

Years: 1967–1980

 The L48 is the original 350 cu in (5.7 L), solely available for 1967 in the Super Sport version of Camaro SS 350 (1967-up) or Chevy II/Nova in 1968-1979. In 1969 it was used in almost all car lines; Camaros, Impalas, El Caminos, Chevelles & Novas. 1969 L48's use a Hyd Cam, 4bbl Quadrajet carburetor, cast pistons, 4-bolt main casting number 010 Blocks & casting number 041 or 186 heads. Power output was 300 hp SAE and 380 lb·ft torque. Compression ratio was 10.25:1. The compression ratio of the L48 was lowered to 8.5:1 in 1971.

 In 1972 the only way to get a L48 (4bbl V8) in a Chevrolet Nova was to get the Super Sport Package. This is indicated by the fifth digit in the VIN being a "K". 1972 was the only year you could verify the Super Sport package by the VIN.

 The L48 V8 was the standard engine in the 1975-1980 Chevrolet Corvette. The L48 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.

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[] L65

Years: 1972 – 1976

  The 2bbl carburetor version of the LM1 350.

[] LM1

Years: 1972 – 1988

The LM1 is the base 5.7 L (350 cu in) with a 4-barrel carburetor (usually with a Rochester Quadrajet) 155-175 hp engine in passenger cars to 1979 as a retail option (its final use with a retail passenger car was the 1981 Camaro Z28) and police package 9C1 A/G (Malibu to 1981) and B-bodies (Caprice, Impala) until 1988 (retail market GM rear wheel drive/V8s sold to the general public had a maximum 5.0L displacement with the exception of its musclecar survivors e.g. Corvette and F-bodies (Camaro IROC Z or Trans Am). Throughout its lifespan, it received either a points, electronic, and/or computer-controlled spark system, to conventional and feedback carburetors. The LM1 was superseded by the L05 powerplant after 1988.

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[] 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. 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 supposedly had a lower nickel content but thicker cylinder deck, and post 1974 heads of the small block Chevrolet used less iron, and were lighter weight, crack-prone, 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.

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[] LT-1

Years: 1970 – 1972

Generation II V8 from 1991-1997, are "LT1"

  Generation V V8, are LS-based "GM LT1"

LT-1 from a 1970 Chevrolet Camaro Z28

  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 factory rated at 370 bhp in the Corvette, and 360 bhp at 6000 rpm and 380 lb-ft at 4000 in the Camaro Z28[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, and Camaro Z28. Power was down in 1971 to dual-rated 330 bhp, 255 nethp 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 only, rather than gross, measurement) to 255 bhp and 280 lb-ft.

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[] L82

Years: 1973 – 1980

  The 1973-1974 L82 was a "performance" version of the 350 that still used the casting number 624 76cc chamber "2.02" heads but with a Rochester Quadra-jet 4bbl carburetor and dual-plane aluminum intake manifold, the earlier L46 350 hp 350 hydraulic-lifter cam, and 9:1 compression forged-aluminum pistons producing 250 bhp (`71 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 220 bhp and 260 lb-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. This engine was also available on the Chevrolet Camaro.

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[] 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 hotter cam and computer control spark advance, replacing the vacuum advance. The L81 was unique in that it was the only Corvette engine that employed a "smart carburetor." The Rochester Quadrajet from 1980 was modified to allow electronic mixture control, and an ECM (Engine Control Module), supplied with data from an exhaust oxygen sensor, modified the fuel/air mixture being fed to the engine.

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[] LT-9

Years: 1981 - 1986

  The LT-9 served as GM's truck-based Heavy Emissions variant of the 5.7 L (350 cu in) supplied in K20/K30 pickups and with the P30 chassis used for motorhomes and stepvans.

  The LT-9's listed specifications are 160 bhp @ 3800 rpm and 250 lb-ft of torque @ 2800 rpm with 8.3:1 compression. LT-9's are carbureted with Rochester Quadrajets from factory and are generally 4-bolt mains. The LT-9 is often known by VIN code as the "M-code 350."

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[] 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.

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[] L98

Years: 1985 – 1992

 Generation IV V8, are "GM L98"

  The new 1985 L98 350 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 1987-1989 (245 bhp with 3.07:1 rear axle ratio (1988-1989 only), and 245 bhp in 1990-1991 (250 bhp with 3.07:1 rear axle). Aluminum cylinder heads (Corvette only) were released part way through the 1986 model run, modified for 1987 with D-ports, and continued through the end of L98 Corvette production in 1991 (still used on ZZx 350 crate engines until 2005 when the ZZ6 received the Fast Burn heads). The L98 V8 was optional on Jan. '87-'92 Chevrolet Camaro & Pontiac Firebird models (rated at 225 hp-245 hp and 330 lb·ft-345 lb·ft . 1987 versions had 10 hp and 15 lb·ft more and a change to hydraulic roller camshaft. Compression was up again in 1990 to 9.5:1 Camaro/Firebird and 10:1 Corvettes, but rated output stayed the same.

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[] L05

Years: 1987 – 1996

  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,

Also used in the following vehicles:

* 1992-1993 Buick Roadmaster sedan and station wagon

* 1990-1992 Cadillac Brougham (optional engine)

* 1993 Cadillac Fleetwood

* 1989-1993 Chevrolet Caprice 9C1 police package (roller cam); 1A2-optioned special service station wagon

* 1992-1993 Chevrolet Caprice Wagon (optional engine)

* 1993 Chevrolet Caprice LTZ

* 1992 Oldsmobile Custom Cruiser Wagon (optional engine)

* 1995-1996 AM General Hummer H1

  L05s were used primarily with casting number 14102193 (64cc combustion chambers) cylinder heads with swirled intake ports - the intake ports were designed for fuel economy (the design was also shared with the 103 heads used on the 4.3L with TBI). The swirl ports (known to GM as a vortex chamber) along with the irregular shape of the combustion chambers limit the airflow and horsepower output where they did not provide a fast burn, later phased in with the 1996+ Vortec heads. A majority of the L05s used with the truck/vans had conventional flat tappet camshafts while the Caprice 9C1 (1989–93) had a roller cam. 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.

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[] L31

Years: 1996 - 2002

  The Vortec 5700 L31 (Vin code 8th digit "R") is a V8 truck engine. Displacement is 5.7 L. It is the last production Generation I small-block from Chevrolet. The cylinder heads feature combustion chambers and intake ports very similar to those of the LT1 V8, but without the reverse-flow cooling. As such, the L31 head is compatible with all older small-blocks, and is a very popular upgrade. It offers the performance of more expensive heads, at a much lower cost. It does, however, require a specific intake manifold (A 5.7L, 350 CI L31, Vortec engine has eight bolts attaching the intake manifold or four per head, as opposed to the traditional six bolts per head twelve in total found on older Chevrolet small blocks). The L31 was replaced by the 5.3 L 5300 LM7. The 2002 model year was the final year for the L31 5.7 L small block V-8 whose origins date back to 1955. The Vortec 5700 produces 255 hp to 350 hp at 4600 rpm and 330 lb·ft to 350 lb·ft of torque at 2800 rpm. It is currently being produced as a crate engine for marine applications and automotive hobbyists as the 'RamJet 350' with minor modifications. 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 despite its cast iron construction. Using this "MARINE" intake will allow the use of common types of Bosch-style injectors with various flow rates while still maintaining emission compliance.

L31 applications:

* 1996-2002 Chevrolet Express/GMC Savana full-size vans

* 1996-1999 Chevrolet/GMC C/K full-size trucks

* 1996-1999 Chevrolet Suburban/GMC Suburban full-size long-wheelbase SUVs

* 1996-2000 Chevrolet Tahoe/GMC Yukon. full-size short-wheelbase SUVs

* 2000 Chevrolet Tahoe Limited / Tahoe Z71 models. full-size short-wheelbase SUVs

* 1999-2000 Cadillac Escalade

L31 TBI applications:

* 1996 G-Series vans over 8,500 lb GVW w/ 4L80E transmission

Special applications:

* Oscar Mayer Wienermobile

* Isuzu Box Trucks

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