General Chevy Small Block V-8 Data - 4.00 Bore Family
|General Chevy Small Block V-8 Data|
|3.75 Bore Family|
|4.00 Bore Family|
|4.125 Bore Family|
|3.670 Bore Family|
|3.50 Bore Family|
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 trucks. 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 1990’s.
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-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 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.
The 350 first appeared as a high-performance 295 hp L-48 option for the 1967 Chevrolet Camaro. Two years later it was made available in the Nova, and finally in 1969 the balance of the Chevrolet line received the 350. Many variants followed:
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, El Caminos, 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 L-48 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 L-48 was the standard Corvette engine and produced 180 hp (134 kW) and 270 lb·ft (366 N·m). The 1980 L-48 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 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.
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 (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.
Post 1971 blocks had a lower nickel content but thicker cylinder deck, and post 1971 heads of the small block chevy used less iron in them and are lighter wight, but less powerfull because of the lower compression ratios used.
The 1972 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 (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.
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.
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).
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 (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.
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)). Aluminum cylinder heads (Corvette only) were released part way through the 1986 model run and continued through the end of L98 Corvette production in 1992.
The L98 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.
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.
The LO5 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 LO5 was also used with the following vehicles:
- 1992/1993 Buick Roadmaster sedan and station wagon
- 1990 - 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)
LO5 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. It is known as the Vortec 5700 and 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.
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.
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. The 302 used the same crank as the 265 and the 283. When the journal size increased to the standard medium journal size, 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