GM Small-Block engine encyclopedia topics

Chevrolet Small-Block V8 engine
Manufacturer:	General Motors
Production:	1955–2002
Successors:	GM LT engine, GM LS engine
Type:	small-block V8
265
Production:	1954–1956
Displacement:
Power:	-
Bore and Stroke:
283
Production:	1957–1967
Displacement:
Power:	-
Bore and Stroke:
307
Production:	1968–1973
Displacement:
Power:	-
Bore and Stroke:
327
Production:	1962–1969
Displacement:
Power:	-
Bore and Stroke:
302
Production:	1967–1969
Displacement:
Power:
Bore and Stroke:
400
Production:	1970–1981
Displacement:
Power:	-
Bore and Stroke:
262
Production:	1975–1976
Displacement:
Power:
Bore and Stroke:
305
Production:	1976–1992
Displacement:
Power:	-
Bore and Stroke:
350
Production:	1967–2002 (production ceased in 2002 for USA production only; still manufactured in Mexico for GM's Goodwrench Replacement Engines)
Displacement:
Power:	-
Bore and Stroke:

Introduction

Chevrolet's small-block V8 is a famous automobile engine. Nicknamed "mouse motor (opposed to the big block engines, nicknamed "rat") for its compact dimensions compared to other V8 engines of the time, production began in 1955 with the 265 engine. By 1957 it had grown to , and with the optional Rochester mechanical fuel injection, it became one of the first production engines ever to make one horsepower per cubic inch. This engine was used to power the Corvette, and the Bel Air at that time. It would later be extended to other vehicles as well, and replace the old style 265 V8s. The displacement changed over the years, eventually reaching , but none caught on like the small-block. This engine is still in production today at General Motors Toluca, Mexico plant (primarily for the GM over-the-counter Goodwrench powerplants), but is no longer offered in current model year vehicles since the year 2004. Its production numbers were impressive, with more than 90,000,000 built. It has been produced in carbureted, mechanical fuel injection, and electronic fuel injection forms.

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

Although Buick, Cadillac, Oldsmobile, and Pontiac also designed V8 engines (see list of GM engines), it was Chevrolet's small-block that became the GM corporate standard. Over the years, every American General Motors division except Saturn used the Chevrolet small-block, and its descendants (see GM LT engine and GM LS engine) continue as the company's mainstream V8 design today.

The small-block was on the Ward's 10 Best Engines of the 20th Century list.

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.

Major Versions

Generation 1

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. There were, however many minor changes made to the engine over the years; these changes are listed below.

1955 - The first year of introduction in only. As was fairly common for the time, no provision for an oil filter was included in the engine design.
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.
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). 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. 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.
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. This change resulted in significant power increases.

SB2 and SB2.2

(Small Block/second generation) This engine was produced from 1996 to the present for racing applications only. The cylinder heads were redesigned and the lifter bores were offset. The valve sequence for each head was changed from the traditional E-I-I-E-E-I-I-E to a new I-E-I-E-E-I-E-I and because of this the camshaft was redesigned.

Generation II

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

Generation III / IV

See the GM LS engine page for more information on the current family of General Motors small-block V8s.

Early Small Blocks

The first small block Chevrolet V-8 was a engine that was developed in 1955 for the Corvette. Displacement and power eventually reached and (in prototypes) before the Corvette switched to Chevrolet big-block power. Although less powerful than big blocks, small block engines have remained popular due to their lower cost (including the cost of performance add-ons) and solid performance and reliability.

265

The V8 was the first Chevrolet small block. Designed by Ed Cole's group at Chevrolet, it filled the power gap in the 1955 Corvette lineup, producing an impressive . The little engine went from drawings to production in just 15 weeks. Besides its compact dimensions, the small-block was known for its novel green-sand foundry construction process.

Dimensions were oversquare - 3.75 in (95 mm) bore and 3 in (76 mm) stroke. The small-block's 4.4 in (111.8 mm) bore spacing would continue in use for decades. It was a pushrod cast-iron engine with hydraulic lifters and a 2-barrel or 4-barrel Rochester carburetor. The 1955 conventional passenger car version produced with a 2-barrel carburetor, or could be upgraded at extra cost to a "Power Pack" version conservatively rated at with a four-barrel Rochester and dual exhaust. The first production year of this engine had no provision for oil filtration built into the block; however, an add-on filter mounted on the thermostat housing was installed during production. Due to the lack of adequate oil filtration provisions, the '55 model year block is typically only desirable to period collectors.

The 1956 Corvette introduced three versions of this engine - , with twin 4-barrel carbs, and with a high-lift cam.

1955, 1956 Chevrolet Corvette
1955 Chevrolet, (2-barrel) and (4-barrel)

283

The V8 was introduced in 1957. It was a version of the with a larger bore at 3.87 in (98 mm). There were five different versions ranging from to 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 engine featured Ramjet mechanical fuel injection, allowing the engine to produce per cubic inch, an impressive feat at the time. For 1961, an amazing was available from this unit.

1957-1962 Chevrolet Corvette

302

Chevrolet produced a special engine for Trans Am racing from 1967-1969. It was the product of placing the 3-inch stroke crankshaft from a 283 into a 4-inch bore 327 block. This engine was mostly used in the first-generation Camaro Z28. Just over 100 DZ block 302 engines were used in the, unique to South Africa, Chevrolet Firenza Can Am. Conservatively rated at 290 hp (216 kW), actual output was around . 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.

307

A version was produced from 1968 through 1973. Engine bore was 3.875 inches (98.4 mm) with a stroke.

The 307 replaced the 283 in Chevrolet cars and produced 200 hp (149 kW) SAE gross at 4600 rpm and 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 and 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 , and SAE gross.

One of the biggest myths about the 307 is that all the blocks were cast with a very low nickel content. However, some 307 blocks, such as casting number 3970020 with suffix VxxxxTHA (x's in place for date), had 010 and 020 stamped under the timing chain cover indicating high tin and nickel content.

327

The V8, introduced in 1962, had a bore and stroke of 4 in (102 mm) by 3.25 in. Power ranged from to 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 , with single Carter 4-brl, and , with Rochester mechanical fuel injection. In 1964, horsepower increased to for the now dubbed L76 version, and 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 , Generation III LS6 in 2001. * L76, L84 1963-1965; Chevrolet Corvette. This block is one of three displacements that under went a major change in 1968/1969 when the main bearing size was increased from .

400

A small-block was introduced in 1970 and produced for 10 years. It had a bore and a stroke. Initial output was 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.

Later Small Blocks

This section documents the odd-size small blocks developed after the 350 appeared in 1969. Many of these basic blocks are variations of the 350 design.

262

The 262 was a 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 and . 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 (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

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 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 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, one half of a Rochester Quadrajet. 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 coupled with a THM200-4R overdrive.

305

The 305 variant of the small-block Chevrolet had a displacement of with a 3.736-inch (95 mm) bore and 3.48-inch (88.4 mm) stroke. The 262 was considered underpowered for use in vehicles with a wheelbase greater than 110 inches, so GM engineers decided to increase the bore diameter from and increase the stroke from (from the 350). Some performance enthusiasts have noted a marked resistance to performance upgrades on the 305 because of its small bore, poor selection of aftermarket cylinder heads, and the relatively high availability of engines.

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).

After 1996, its usage was limited to light trucks and SUVs as the Vortec 5000.

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	125	235	w/2bbl.
1979	130	245	w/2bbl.
1979	155	225	w/4bbl.
1981	300	350	w/4bbl

The 305 was used in the following cars:

1976-1993 Chevrolet Caprice (includes Impala)
1986 Pontiac Parisienne Brougham
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 after 1980)
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

LG3

Years:1976-1980

Dualjet 2 bbl carb version with 8.5:1 compression.

LG4

Years: 1980-1987

The LG4 was the "low output" (compared to the L69). It produced - and -. 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 from the rating in 1985.

L69

Years: 1983-1986

The L69 was the last true H.O. engine. The High Output , 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 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 @ 4800 and 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 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 53 cc chambers, a specially calibrated 4bbl Q-Jet, the weird hybrid centrifugal/vacuum advance distributor with ESC knock sensor setup, and lower restriction exhaust. The engine made @ 4,600 and @ 2,000 rpm.

L03

Years: 1987-95

The L03 was the "low output" (compared to the 305 TPI LB9). It produced and of torque (at 4,400 rpm and 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.

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 and and varied between - (with - of torque) over the years offered. It was an option on all 1985-1992 Chevrolet Camaro & Pontiac Firebird models.

350

The first generation of Chevrolet small-blocks began with the 1955 Chevrolet V8. But it was the series that came to be emblematic of the Chevrolet small block V8 engine. The engine's physical dimensions (oversquare 4.00-inch bore and 3.48-inch stroke, 102 mm by 88 mm) are nearly identical to the LS2 engine of today, but much has changed. It is by far the most widely used Chevrolet small-block; it has been installed in everything from station wagons to sports cars, in commercial vehicles, and even in boats and (in highly modified form) airplanes.

First usage of the 350 was in the 1967 Chevrolet Camaro and 1968 Nova producing 295 horsepower (gross); other Chevrolet vehicle lines followed suit in the year 1969.

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.

ZQ3

Years: 1969, 1970, 1972-1975

The ZQ3 was the standard engine in the 1969-1970 Chevrolet Corvette. It was a version of the 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 and with 8.5:1 compression, dropping another in 1973. 1975 saw the ZQ3 at and .

L46

Years: 1969, 1970

The L46 was an optional engine on the 1969-1970 Chevrolet Corvette. It was a , version of the ZQ3 with higher 11:1 compression.

LT-1

Years: 1970-1972

The LT-1 was the ultimate 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 and . It was available on the Corvette and Camaro Z28. Power was down in 1971 to and with 9:1 compression, and again in 1972 (the last year of the LT-1) to and .

There was also a later small-block engine called the "LT1".

L48

Years: 1967-1980

The L-48 is the original , 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 and with an 8.5:1 compression ratio.

The 1976-1979 L48 was the standard Corvette engine and produced and . The 1980 L48 stood at and 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 (net). Beginning in 1974 the hp was reduced for several years until it reached a low of (net) in 1975, before rising again.

L82

Years: 1973-1980

The 1973-1974 L82 was a "performance" version of the 350 producing and from 9:1 compression. It was down to and for 1975. It was the optional engine again in 1976-1977, producing more. The 1978 L82 recovered somewhat, producing and , and then and more for 1979. 1980 saw yet another and .

L81

Years: 1981

The L81 was the only Corvette engine for 1981. It produced and 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 and from 9:1 compression. This was again the only engine on the new 1984 Vette, at and . The L83 added Cross-Fire fuel injection (twin throttle-body fuel injection).

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 and . It was standard on all 1985-1991 Corvettes (rated at - and -). Optional on 87-92 Chevrolet Camaro & Pontiac Firebird models (rated at - and -) 1987 versions had and more thanks to 9.5:1 compression. Compression was up again in 1991 to 10:1 but output stayed the same.

LM1

The LM1 is the base 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.