Home arrow Corvettes arrow Small-Block
Chevrolet Small-Block Engine E-mail
Chevrolet Small-Block Engine

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" LE 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 that produced a then milestone one horsepower per cubic inch, the 327 cu in (5.4 L) , 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Finally superseded by GM's Generation II LT and Generation III V8 in the early 2000s and discontinued in 2004, the engine is still made by a GM subsidiary in Mexico as an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.

Confusion with LT and LE engines

The original Chevrolet-designed small-block is a specific family of engines manufacturerd 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 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.

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 engines 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, it is still in production today at General Motors' Toluca, Mexico plant under the company's "Mr Goodwrench" brand.

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

Chevrolet tested the small-block twice with no water and no oil at wide-open throttle. The first time it lasted an hour and 15 minutes and the second time it lasted two hours.

Original small-blocks

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. Chronologically, the original series of small-blocks include:

265


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 in-line six, the 165 hp (123 kW) 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


283

The 265 ci V-8 was bored out to 3.87 in (98 mm) in 1957, giving it a 283 cu in (4.6 L) displacement. 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. Power was up a bit each year for 1958, 1959, and 1960.

The 1957 Ramjet mechanical fuel injection version produced an even 1 hp (1 kW) per cubic inch, an impressive feat at the time. By 1961, a prolific 315 hp (235 kW) was generated by this unit.

327


327

The 327 cu in (5.4 L) V8, introduced in 1962, had a bore and stroke of 4 in (102 mm) by 3.25 in. Power ranged from 250 hp (186 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-brl, 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 L76 version, and 375 hp (280 kW) for the fuel injected L84 respectively, making the L84 the most powerful naturally aspirated, single-cam, production small block V8 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 under went a major change in 1968/1969 when the main bearing size was increased from 2.30 to 2.45 inches (58.4–62.2 mm).

350


350

The 350 first appeared as a high-performance 295 hp L48 option for the 1967 Chevrolet Camaro. A year later it was made available in the Nova, in 1969 the balance of the Chevrolet line. Many variants followed:

    * L48

Years: 1967-1980

The L-48 is the original 350 cu in (5.7 L), available only in the Camaro or Chevy II/Nova in '67 & '68. In '69 it was used in almost everything; Camaros, Corvettes, Impalas, Chevelles & Novas. From '75-'80 it was available only in the Corvette. L-48's use a Hyd Cam, 4bbl Qjet, Cast pistons, 2 bolt main caps, "Pink" Rods, #0014 Blocks & #993 heads. Power output ranges from 300HP(gross) down to 175HP(net).

The L48 was the standard engine in the 1971 Chevrolet Corvette. It produced 270 hp (201 kW) and 360 lb·ft (488 N·m) with an 8.5:1 compression ratio.

The 1976-1979 L48 was the standard Corvette engine and produced 180 hp (134 kW) and 270 lb·ft (366 N·m). The 1980 L48 stood at 190 hp (142 kW) and 280 lb·ft (380 N·m) from 8.2:1 compression.

In 1972 the only way to get a L48 (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.

In 1973 the "L-48" had cold air induction (throttle activated) and developed 190 hp (142 kW) (net). Beginning in 1974 the hp was reduced for several years until it reached a low of 165 hp (123 kW) (net) in 1975, before rising again.

    * ZQ3

Years: 1969, 1970, 1972-1975

The ZQ3 was the standard engine in the 1969-1970 Chevrolet Corvette. It was a 300 hp (224 kW) version of the 350 cu in (5.7 L) 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.

The 1969 ZQ3 produced 200 hp (149 kW) and 300 lb·ft (407 N·m) with 8.5:1 compression, dropping another 10 hp (7 kW) in 1973. 1975 saw the ZQ3 at 165 hp (123 kW) and 255 lb·ft (346 N·m).

    * L46

Years: 1969, 1970

The L46 was an optional engine on the 1969-1970 Chevrolet Corvette. It was a 349 hp (260 kW), 380 lb·ft (515 N·m) version of the ZQ3 with higher 11:1 compression.

    * LT-1

Years: 1970-1972

The LT-1 was the ultimate 350 cu in (5.7 L) V8, becoming available in 1970. It used solid lifters, 11:1 compression, a high-performance camshaft, and a Holley four-barrel carburetor on a special aluminum intake to produce 370 hp (276 kW) and 380 lb·ft (515 N·m). It was available on the Corvette and Camaro Z28. Power was down in 1971 to 330 hp (246 kW) and 360 lb·ft (488 N·m) 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 hp (190 kW) and 280 lb·ft (380 N·m).

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

302


302

Chevrolet produced a special 302 cu in (4.9 L) engine for Trans Am racing from 1967-1969. It was the product of placing the 3-inch stroke crankshaft into a 4-inch bore block. Although the 283 also used a 3-inch stroke crankshaft, it was a low performance cast iron crankshaft. The crankshaft for the 302 was specially built of forged steel. This engine was used only in the first-generation Camaro Z28. Conservatively rated at 290 hp (216 kW), actual output was around 375 hp (280 kW). This block is one of 3 displacements that underwent a transformation for the 1968/1969 period when the main bearing size was increased from 2.30 in to 2.45 in.

A letter from G.D. Thompson, Chevrolet Engineering Laboratory, dated June 5, 1967 to D.A. Martens, Engineering Department, subject Z-28 Service Pack Power Breakdown states "engine capable of 448 HP will deliver 432HP in full vehicle dress" .... "as installed data corrected to 100 degree brake and 29.52hg dry barometer yields a maximum of 403.8 HP. This correction more closely represents what is available when installed in a vehicle" *bhp@7400rpm

307


307

A 307 cu in (5 L) 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 replaced the 283 in Chevrolet cars and produced 200 hp (149 kW) SAE gross at 4600 rpm and 300 lb·ft (407 N·m) of torque at 2400 rpm in the 1960s. The later emissions-modified versions produced just 115 hp (86 kW) SAE net, giving the engine one of the lowest power-per-displacement ratings of all time. Chevrolet never produced a high-performance version of this engine, though they 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.

400


400

A 400 cu in (6.6 L) small-block was introduced in 1970 and produced for 10 years. It had a 4.125-inch (104.8 mm) bore and a 3.75-inch (95.3 mm) stroke. 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 the A-Body and B-Body line. While popular with circle-track racers, the engine was prone to cooling troubles if cylinder heads without steam holes were used. They mostly put out 250 hp stock. Due to the way the block was designed, the 2 bolt main engines were stronger than the 4 bolt versions. The 509 2 bolt main block is the most desirable 400 block.


Later Small Blocks

Multiple variations of the original small-block were introduced after 1970's bore-out to 400 cubic inches, many based on the already much modified 350 design. Chronologically, they include:

350 variants


350 variants

    * L82

Years: 1973-1980

The 1973-1974 L82 was a "performance" version of the 350 producing 250 hp (186 kW) and 285 lb·ft (386 N·m) from 9:1 compression. It was down to 205 hp (153 kW) and 255 lb·ft (346 N·m) for 1975. It was the optional engine again in 1976-1977, producing 5 hp (4 kW) more. The 1978 L82 recovered somewhat, producing 220 hp (164 kW) and 260 lb·ft (353 N·m), and then 5 hp (4 kW) and 10 lb·ft (14 N·m) more for 1979. 1980 saw yet another 10 hp (7 kW) and 15 lb·ft (20 N·m).

    * L81

Years: 1981

The L81 was the only 5.7 L (350 cu in) Corvette engine for 1981. It produced 190 hp (142 kW) and 280 lb·ft (380 N·m) from 8.2:1 compression, exactly the same as the 1980 L48, but added computer control spark advance, replacing the vacuum advance.

    * L83

Years: 1982, 1984

The 1982 L83 was again the only Corvette engine (and only available with an automatic transmission) producing 200 hp (149 kW) and 285 lb·ft (386 N·m) from 9:1 compression. This was again the only engine on the new 1984 Vette, at 205 hp (153 kW) and 290 lb·ft (393 N·m). 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.

    * L98

    For the new Generation IV V8, see GM L98.

Years: 1985-1992

The new 1985 L98 added tuned-port fuel injection "TPI", which produced 230 hp (172 kW) and 330 lb·ft (447 N·m). It was standard on all 1985-1991 Corvettes (rated at 230 hp (172 kW)-250 hp (186 kW) and 330 lb·ft (447 N·m)-350 lb·ft (475 N·m)). 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 LO5 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 1996 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
    * 1991/1992 Cadillac Brougham (optional engine)
    * 1993 Cadillac Fleetwood
    * 1992/1993 Chevrolet Caprice Wagon (optional engine)
    * 1993 Chevrolet Caprice LTZ
    * 1992 Oldsmobile Custom Cruiser Wagon (optional engine)

L05 usage was replaced by the GM 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 LO5 in 1996 - known as the Vortec 5700. 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.

    * Mr. Goodwrench

The GM Goodwrench 350 crate engine comes in several variations. The lowest priced uses 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.

262


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). The 262 was underpowered and was replaced by the 305 the following year.

This was Chevrolet's second 4.3 L-displacement powerplant; two other Chevrolet engines displaced 4.3 L: the Vortec 4300 (a V6 based on the Chevrolet 350, with two cylinders removed), and a derivative of the LT1 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

305


305

The 305 5.0L variant of the small-block Chevrolet introduced in 1975 had a displacement of 305 cu in (5 L) with a 3.7350-inch (94.869 mm) bore, and 3.4803-inch (88.4 mm) stroke. Some performance enthusiasts have noted a marked interest to performance upgrades on the 305 because of its mod´s opportunities, good selection of performance parts, and the relatively high availability of 305 cu in (5 L) engines. Little mods on cooling system, better intake and exhaust, internal efficiency and fuel delivery, can turn a 305 into a solid performance engine making the same or even more horsepower than than a stock 350 5.7L engine.

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:

    * 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)
    * 1976-1992 Chevrolet Camaro
    * 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 as the Vortec 5000.

    * LG3

Years:1976-1980

Dualjet 2 bbl carb version with 8.5:1 compression.

267


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 267 cu in (4.4 L) had the 350's crankshaft stroke of 3.48" and the smallest bore of any small-block, 3.500 in. The 3.500" 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.

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 L) as its base V8 engine.

    * LG4

Years: 1980-1987

The LG4 was the "low output" 305 cu in (5 L) (compared to the L69). It 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 was the last true H.O. engine. The High Output 5 L (305 cu in) , featuring higher compression of 9.5:1 with heads of the to-be-discontinued LU5 Cross-Fire fuel injection engine, and utilizing camshaft and 4" catalytic converter of the 5.7 L (350 cu in) L83 which was used on the Corvette of 1982 and 1984. Complete with a 2.75 inch exhaust system, topped by a recalibrated 4-barrel carburetor, dual snorkel air cleaner assembly, aluminum intake manifold, aluminum flywheel, electric cooling fan, and furthermore a knock sensor including more aggressive spark timing, this engine produced 190 hp (142 kW) @ 4800 and 240 lb·ft (325 N·m) of torque @ 3200 rpm. In most cases, being mated to a 3.73 or 3:42 ratio limited slip rear axle and a T5 5-speed or 700R4 automatic, this engine provided its driver with a wide range of rpm to play in.

    * LE9

Years: 1981-1986

The LE9 5 L (305 cu in) was the truck/van version of the High Output 305. It also had flattop pistons for a 9.5:1 compression ratio, the "929" truck 350 camshaft for more torque, 14022601 casting heads featuring 1.84/1.50" valves and 58 cc chambers, a specially calibrated 4bbl Q-Jet, the hybrid centrifugal/vacuum advance distributor with ESC knock sensor setup, and lower restriction exhaust. The engine made 210 hp (157 kW) @ 4,600 and 250 lb·ft (339 N·m) @ 2,000 rpm.

    * LB9

Years: 1985-1992

Introduced in 1985, the LB9 was the first Chevrolet small block to have tuned-port fuel injection (TPI). It 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. It was an option on all 1985-1992 Chevrolet Camaro & Pontiac Firebird models.

    * LO3

Years: 1987-95

The LO3 was the "Low Output" 5 L (305 cu in) (compared to the 305 TPI LB9). It produced 170 hp and 255 lb·ft (346 N·m) of torque; 190 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. The TBI uses a unique injector firing scheme: for every rotation of the engine, each injector fired twice.
 

427 Small Block


427 Small Block

Chevrolet announced the 2008 Corvette 427 Limited Edition Z06, a limited-production model that pays homage to the big-block Stingray models of the mid-1960s. The 427 designation refers to the cubic-inch displacement for the highest-performance engines offered between 1966 and ’69 – and is also the cubic-inch equivalent of the Z06’s 7.0L LS7 small-block V-8.

“The heritage of the 427 designation with the Corvette is legendary,” said Harlan Charles, Corvette product manager. “Recognizing the tie-in of the original 427 engine and the LS7’s 427-inch displacement has been on the Corvette team’s mind since the Z06 was introduced, and we’re thrilled to express it in this special model.”

Available under order code Z44, this special Z06 enters production spring 2008. Only 427 will be offered in the United States and Canada, with 78 more exported outside North America. That’s a total of 505 production vehicles – the same number of horsepower produced by the LS7 engine.

The Corvette Z06 that is the foundation for the 427 Limited Edition offers carefully executed levels of capability and technology, making it one of the best performance values on the market.

The Z06’s LS7 7.0L engine reintroduced the 427-cubic-inch engine to the Corvette lineup. It uses racing-derived lightweight technology, including titanium connecting rods and intake valves, to help boost horsepower and rpm capability – it is rated at 505 horsepower (377 kW).* The only transmission offered with the Z06 is a six-speed manual.

History of the Corvette and the 427 engine

The Chevrolet Mark IV V-8 debuted in the Corvette in 1965 and was dubbed the big-block, because it was physically larger in all respects than Chevy’s other V-8 engine, which became known as the small-block. In ’65, the big-block was offered in a 396-cubic-inch displacement, with a maximum rating of 425 gross horsepower (317 kW). In 1966, the big-block received larger cylinder bores and grew to its legendary 427-cubic-inch form. It came in two power levels: 390 hp (291 kW) and 425 hp.

By 1967, the Corvette’s 427 engine was a legend in its own time and was offered with a unique induction system that featured an inline trio of two-barrel carburetors. Known as the “L71” (its order code), it was characterized by a large, chrome triangular air cleaner assembly. It was rated at 435 gross horsepower (324 kW). The ’67 big-block Corvettes were easily distinguished from their small-block brethren by a raised “stinger” hood.

A handful of Corvettes with the “L88”-code 427 engine slipped out of the factory in 1967, each rated at 430 horsepower (321 kW), but the L88 would be more closely associated with the redesigned 1968 and ’69 models. The L88 breathed through a single four-barrel carburetor rather than the L71’s three two-barrels. The triple-carburetor induction system was still available, however, as the Corvette was offered with both the L88 and L71 versions of the 427.

No less than six versions of the engine were offered in 1969, the final year for the 427. They included the L88, the L71 and a very rare ZL1 427 that was built with a lightweight aluminum cylinder block. Only two regular-production Corvettes were built with the ZL1 engine, putting them on the short list of the most collectible Corvettes in history.

The big-block increased in size to 454 cubic inches in 1970, and the original big-block engine family exited the Corvette lineup after the 1974 model year. The 2008 Corvette Z06’s LS7 engine offers big-block displacement and horsepower, but in a more efficient small-block architecture.
 

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 - Oil filtration was introduced, using a sock style filter in a canister.
    * 1957 - The engine came with only front mounts, the side mount bosses were present but not drilled and tapped leaving its retrofitting problematic.
    * 1962 - The block's cylinder wall casting was revised to allow four inch bores. Previously, only certain years of the 283 engine (1958-1962) could be bored safely to four inches.
    * 1968 - The main journal diameter was increased to 2.45 in from 2.30 in 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.
    * 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 1985, 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 that acts some what like a carburetor.
    * 1992 - The cooling system was revised by moving in the direction of reverse cooling and rebranded as the LT1. The coolant was routed through the cylinder heads first. The changes made to the blocks and heads made these components incompatible with other small block Chevy engines without heavy modifications. The engine, along with the cooling route changes, also featured a cam driven water pump and distributor. The distributor was dubbed the "optispark", and had two revisions. The oil pump remained in the standard location cam driven with a drive mechanism that resembled a distributor lower section. The intake manifold had very short runners, and was dubbed by GM as "untuned". The internal components of the motor, as far as internal dimensioning, remain unchanged. The engine was used in the automotive line and was never installed in the truck line.
    * 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 from four bolts per cylinder head instead of the traditional six.

Source: Wikipedia




Bookmark this article
Digg!Reddit!Del.icio.us!Google!Live!Facebook!Slashdot!Netscape!Technorati!StumbleUpon!Spurl!Newsvine!Furl!Fark!Blogmarks!Yahoo!Ma.gnolia!Squidoo!FeedMeLinks!Free social bookmarking plugins and extensions for Joomla! websites! title=
 

Sponsored Links

 

Sponsors

 
Advertise with us
Do you want to
advertise on this site?
We have multiple
options for you:
  • Banners
  • Banner Rotations
  • Advertising Blocks
  • Link Options
  • Ad Sense
Contact us and we will
explain all the details!

Vettester.com -

Your business partner!

Check out the Top Corvette Sites

Top Corvette Sites - Net Corvettes

Corvette Top Sites

Vote for us on the Vette Top 100

 

Sponsored Links


Fatal error: Class 'JTEXT' not found in /home/frankpope/public_html/components/com_joomlastats/count.classes.php on line 867