Chevrolet Small-Block V8 engine
Manufacturer:General Motors
Successors:GM LT engine, GM LS engine
Type:small-block V8
Displacement:265 in³ (4.3 L)
Power:162–240 hp (121–179 kW)
Bore and Stroke:3.750" x 3.00"
Displacement:283 in³ (4.6 L)
Power:220–315 hp (164–235 kW)
Bore and Stroke:3.875" x 3.00"
Displacement:307 in³ (5.0 L)
Power:115–200 hp (86–149 kW)
Bore and Stroke:3.875" x 3.25"
Displacement:327 in³ (5.4 L)
Power:250–375 hp (186–268 kW)
Bore and Stroke:4.000" x 3.25"
Displacement:302 in³ (4.9 L)
Power:290 hp (216 kW)
Bore and Stroke:4.000" x 3.00"
Displacement:400 in³ (6.6 L)
Power:150-265 hp (112-197 kW)
Bore and Stroke:4.125" x 3.75"
Displacement:262 in³ (4.3 L)
Power:110 hp (82 kW)
Bore and Stroke:3.670" x 3.10"
Displacement:305 in³ (5.0 L)
Power:130–250 hp (97–186 kW)
Bore and Stroke:3.736" x 3.48"
Production:1967–2002 (production ceased in 2002 for USA production only; still manufactured in Mexico for GM's Goodwrench Replacement Engines)
Displacement:350 in³ (5.7 L)
Power:145–370 hp (108–276 kW)
Bore and Stroke:4.000" x 3.48"


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 283 cubic inches, and with the optional Rochester mechanical fuel injection, it became the first production engine 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 400 in³ (6.6 L), but none caught on like the 350 in³ (5.7 L) 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 carburated, 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 350 in³ 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.

Major VersionsRectify

Generation 1Rectify

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 265 cubic inches 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.
  • 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. 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 troublesome leaky 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 4.3L the year before). The troublesome 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).
  • 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 SB2.2Rectify

(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 IIRectify


LT1 from a 1993 Chevrolet Camaro Z28

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 / IVRectify


LS1 from a 1998 Chevrolet Camaro Z28

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

Early Small BlocksRectify

Most current GM small-block V8s (the LT and LS series) trace their lineage to the 1955 265 in³ V8 developed for the Corvette. Displacement and power eventually reached 327 in³ and 509 hp (in prototypes) before the Corvette switched to Chevrolet big-block power. But the small-block lived on, settling in at 350 in³ for decades of performance.


The 265 in³ (4.3 L) 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 195 hp (145 kW). 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 - 210 hp (157 kW), 225 hp (168 kW) with twin 4-barrel carbs, and 240 hp (179 kW) with a high-lift cam.


The 283 in³ (4.6 L) V8 was introduced in 1957. It was a version of the 265 in³ (4.3 L) with a larger bore at 3.87 in (98 mm). There were five different versions ranging from to 283 hp (164 kW to 211 kW) 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.


Chevrolet produced a special 302 in³ (4.9 L) 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.


A 307 in³ (5.0 L) version was produced from 1968 through 1973. Engine bore was 3.875 in (98.4 mm) with a 3.25 stroke.

The 307 replaced the 283 in Chevrolet cars and produced 200 hp (149 kW) SAE gross at 4600 rpm and 300 ft·lbf (410 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 motor, though they did produce, for Outboard Marine Corporation, a high-performance marinized 307, rated at 235 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 210, 215 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.


The 327 in³ (5.4 L) V8, introduced in 1962, had a bore and stroke of 4 in (102 mm) by 3.25 in. Power ranged from to 375 hp (186 kW to 280 kW) depending on the choice of carburetor or fuel injection, camshaft, cylinder heads and intake manifold. In 1962, the Duntov solid lifter cam versions produced 340 hp (254 kW), 344 ft·lbf (466 N·m) with single Carter 4-brl, and 360 hp (268 kW), 352 ft·lbf (477 N·m) with Rochester mechanical fuel injection. In 1964, horsepower increased to 365 for the now dubbed L76 version, and 375 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 ft·lbf (522 N·m) Generation III LS6 in 2001. * L76, L84 1963-1965; Chevrolet Corvette. This block is one of three displacements that underwent a major change in 1968/1969 when the main bearing size was increased from 2.30 in to 2.45 in.


A 400 in³ small-block was introduced in 1970 and produced for 10 years. It had a 4.125 inch bore and a 3.75 inch 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 BlocksRectify

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.


The 262 was a 4.3 L (262 in³) 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 ft·lbf (264 N·m). The 262 was underpowered and was replaced by the 305 the following year.

This was Chevrolet's second 4.3L-displaced powerplant; two other Chevrolet engines displaced 4.3L: 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" bore, 5.94" connecting rods, and a 3 inch crankshaft stroke).

This engine was used in the following cars:


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 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 V6, which was introduced a year earlier. (The 200 was a Chevrolet V6 motor 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 4.3-4.4L V8 motors produced by General Motors (including the Oldsmobile 260 and Pontiac 265, the small bore 267 shared no parts with the other motors and was phased out after the 1982 model year due to inability to conform to emission standards. Chevrolet vehicles eventually used the 305 (their own 5.0L) coupled with a THM200-4R overdrive.


The 305 variant of the small-block Chevrolet had a displacement of 5.0 L (305 in³) with a 3.736 in (95 mm) bore and 3.48 in (88.4 mm) stroke. The 262 was considered underpowered for use in vehicles with a wheelbase greater than 110", so GM engineers decided to increase the bore diameter from 3.671" to 3.736" and increase the stroke from 3.10" to 3.48" (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 350 in³ 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) ft·lbf (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.
1979 160 235 w/4bbl.

The 305 was used in the following cars:



Dualjet 2 bbl carb version with 8.5:1 compression.


Years: 1980-1987

The LG4 was the "low output" 305 in³/ 5.0L (compared to the L69). It produced 145–170 hp (110–127 kW) and 240–250 ft·lbf (325–340 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 from the rating in 1984.


Years: 1983-1988

The L69 was the so-called High Output 305 in³/ 5.0L, featuring higher compression of 9.5:1 with heads of the to-be-discontinued LU5 Cross-Fire fuel injection engine, and utilizing camshaft and catalytic converter of the 350 in³/ 5.7L 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 and furthermore a knock sensor including more aggressive spark timing, this engine produced 190 hp (142 kW) @ 4800 and 240 ft·lbf (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 Turbo 350 or 700R4, this engine provided its driver with a wide range of rpm to play in.


Years: 1981-1986

The LE9 305 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.


Years: 1987-95

The L03 was the "low output" 305 in³/ 5.0L (compared to the 305 TPI LB9). It produced and of torque (185 HP @ 4,400 / 275 TQ @ 2,400 in 1993-1995 GM trucks). The 305 dropped the Computer-controlled carburetor and received the fuel-injected TBI (throttle-body injection). The TBI unit consisted of two barrels, much like those of a two barrel carb, but instead of "jets", there was a fuel-injector placed above each barrel, resulting in a 2-barrel, 2-injector setup. The TBI uses a unique injector firing scheme, for every rotation of the engine, each injector fired twice.

TBI injection was used on trucks/vans through the 1995 model year, mainly because of its strong torque curve, allowing for heavy towing, hauling and taller axle gearing for fuel economy.


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 ft·lbf (373 N·m) and varied between 190 and 230 hp (with 275 to torque) over the years offered. It was an option on all 1985-1992 Chevrolet Camaro & Pontiac Firebird models.


The first generation of Chevrolet small-blocks began with the 1955 Chevrolet 265 in³ (4.3 L) V8. But it was the 350 in³ (5.7L) series that set the standard for high performance. The engine's physical dimensions (oversquare 4.00 in bore and 3.48 in stroke, 102 mm by 88 mm) are nearly identical to the 400 hp (300 kW) LS2 engine of today, but of course 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.

A 350 is usually common with engine swaps - much of the older, pre-1968 Chevrolet V8s were usually swapped with a later 350 when engine replacement was the norm. It has been known to swap a 350 in place of a different small block since all small blocks are the same on the outside (the external dimensions of a Chevrolet small block are the same).

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 motor 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 motor was produced in Mexico since 1981 as the Targetmaster 350, and now the GM Goodwrench 350.

Note that Buick, Oldsmobile, and Pontiac all produced three entirely different 350 in³ V8 engines that shared nothing in common other than displacement. The Buick 350 had a 3.80 in bore and a 3.85 in stroke (96.52 mm by 97.91 mm), the Oldsmobile 350 had a 4.057 in bore and 3.39 in stroke (103 mm by 86 mm), and the Pontiac 350 had a 3.876 in bore and a 3.75 in stroke (98.5 mm by 89.66 mm).


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 in³ (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 (150 kW) and 300 ft·lbf (407 N·m) with 8.5:1 compression, dropping another 10 hp (7.5 kW) in 1973. 1975 saw the ZQ3 at 165 hp (123 kW) and 255 ft·lbf (346 N·m).


Years: 1969, 1970

The L46 was an optional engine on the 1969-1970 Chevrolet Corvette. It was a 350 hp (261 kW), 380 ft·lbf (515 N·m) version of the ZQ3 with higher 11:1 compression.



LT-1 from a 1970 Chevrolet Camaro Z28

Years: 1970-1972

The LT-1 was the ultimate 350 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 ft·lbf (515 N·m). It was available on the Corvette and Camaro Z28. Power was down in 1971 to 330 hp (246 kW) and 360 ft·lbf (477 N·m) with 9:1 compression, and again in 1972 (the last year of the LT-1) to 255 hp (190 kW) and 280 ft·lbf (380 N·m).

Note that there was a later small-block engine called the "LT1".


Years: 1967-1980

The L-48 is the original 350, available only in the Camaro or Chevy II/Nova in '67 & '68. In '69 it was used in almost eveything; 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 ft·lbf (477 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 ft·lbf (366 N·m). The 1980 L48 stood at 190 hp (142 kW) and 280 ft·lbf (380 N·m) from 8.2:1 compression.

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


Years: 1973-1980

The 1973-1974 L82 was a "performance" version of the 350 producing 250 hp (186 kW) and 285 ft·lbf (386 N·m) from 9:1 compression. It was down to 205 hp (153 kW) and 255 ft·lbf (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 ft·lbf (353 N·m), and 5 hp (4 kW) and 10 ft·lbf (14 N·m) more for 1979. 1980 saw another 10 hp (7.5 kW) and 15 ft·lbf (20 N·m).


Years: 1981

The L81 was the only 350 Corvette engine for 1981. It produced 190 hp (142 kW) and 280 ft·lbf (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. The L81 is the exact same as any ordinary 350 5.7L ci gm motor.


Years: 1982, 1984

The 1982 L83 was again the only Corvette engine (and only available with an automatic transmission) producing 200 hp (150 kW) and 285 ft·lbf (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 ft·lbf (393 N·m). The L83 added Cross-Fire fuel injection (twin throttle-body fuel injection).


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 ft·lbf (447 N·m). It was standard on all 1985-1991 Corvettes (rated at 230-250 hp and 330-350ft·lbf torque). Optional on 87-92 Chevrolet Camaro & Pontiac Firebird models (rated at 225-245 hp and 330-345ft·lbf torque) 1987 versions had 10 hp (7.5 kW) and 15 ft·lbf (20 N·m) more thanks to 9.5:1 compression. Compression was up again in 1991 to 10:1 but output stayed the same.


The LM1 is the base 350 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.


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:

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.


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 to this day. The "MARINE" intake is a potential upgrade for L31 trucks.

See also...Rectify

From the 1950s through the 1970s, each GM division had its own V8 engine family. Many were shared among other divisions, but each design is most-closely associated with its own division:

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


External linksRectify