HISTORY: 305 / 5.0

[] 305 / 5.0L

3.736 in Bore

3.48 in Stroke

305 CID 1976 - 1998

  Designed and built during the era of the gas embargo, CAFE mandates, and tighter emissions, this engine family was designed to become Chevrolet's cost-effective, all-purpose "economy V8" engine line. These were intended to fill the gap where the venerable 283 ('57-'67), & 307 ('68-'73) had been. Bore and stroke were 3.736 in by 3.48 in, utilizing the 350's crankshaft throw. This new engine family would provide better gas economy than the 350, share its basic architecture and many parts with the 350 (thus reducing production costs), and provide customers with more horsepower/torque than Chevrolet's 1970s-era inline 6 and V6 engines. During the early 1980s, when GM was streamlining their engine lineups, the Chevrolet 305 would rise to prominence as General Motors' "corporate" engine, signified by being the standard (and often only) V8 in many GM vehicles. Through much of the 80's, the 305 became General Motors' most common V8, followed closely by Oldsmobile's robust 307. The Chevrolet 305 also became the standard V8 in GM's C/K truck series, and was even used in the Corvette for one year in 1980.

 Crankshafts used with the 305 had the same casting number as the 350 with one discernable difference - the 305 crank is lighter in weight to compensate for engine balancing. (The counterweights are smaller, which makes it unsuitable for use in a 350 where metal would have to be welded back on.) The medium journal 305, like its big-brother 350, would be further developed in the 1990s, although with a reduced 3.00" stroke (using 5.94" connecting rods), into the "Generation II SBC" GM LT-Series engine L99 263

  The Chevrolet 305 is a reliable, fuel efficient V8, easily capable of 200,000 miles, if maintained. From 1976 onward into the early 1980s, these engines were also prone to wearing out their camshaft's lobes very prematurely due to a combination of improper manufacturing and reduced/poor quality controls (a result of GM cost-cutting measures). The 305 is sometimes dismissed in performance circles because of its "lack of power", its small bore size, and difficulty flowing large volumes of air at higher rpms; however, two variants of the '83-'92 305 were notable performers, especially when in comparison to most of the other "performance engines" of that time: the '83 -'88 L69 "High Output 5.0L" (only used in late '83 -early '86 F-body/ late '83 -'88 Monte Carlo SS) and the '85 -'92 LB9 "Tuned Port Injection 5.0L" (F-body only).

 After 1993, its usage was limited to light trucks and SUVs until the 2000 model year (vans and commercial vehicles until 2003). The 305 was sold as a crate motor under the Mr. Goodwrench brand as a replacement motor and as a boat engine for Mercury Marine until late 2014 when it was discontinued. The cylinder block is still in production by GM (part number 10243869) for Sprint Car Spec Racing.

 Engine Variant:

 LG3 1976-1980

 LG4 1980-1988

 LU5 1982-late 83

 L69 late 1983-88

 LE9 1981-1986

 LB9 1985-1992

 LO3 1987-1995

 L30 1996-2003


[] The 305 was used in the following cars:

* 1976-1992 Chevrolet Camaro

* 1977-1993 Chevrolet Caprice (includes Impala)

* 1980 Chevrolet Corvette (California only)

* 1976-1988 Chevrolet Malibu, Chevrolet El Camino/GMC Caballero, and Chevrolet Monte Carlo

* 1976-1979 Chevrolet Monza

* 1976-1979 Chevrolet Nova (also GM X-body clones after 1976)

* 1977-2003 Chevrolet/GMC Trucks, SUVs, Vans

* 1978-1987 Buick Regal (rare after 1980)

* 1975-1979 Buick Skylark

* 1991-1992 Cadillac Brougham

* 1977-1981 Checker Marathon

* 1991-1992 Oldsmobile Custom Cruiser

* 1977 Oldsmobile Omega

* 1978-1980 Oldsmobile Cutlass (U.S. market)

* 1978-1987 Oldsmobile Cutlass (Canadian market)

* 1977-1981 Pontiac Catalina (B-body)

* 1977-1981 Pontiac Bonneville (B-body)

* 1982-1986 Pontiac Bonneville (G-body)

* 1977-1992 Pontiac Firebird

* 1981-1987 Pontiac Grand Prix

* 1978-1981 Pontiac Grand LeMans (A/G-body, includes Grand Am)

* 1982-1986 Pontiac Parisienne (B-body)

* 1982-1986 Pontiac Parisienne Safari (B-body wagon)

* 1979 Pontiac Sunbird

[] LG3

Years:1976 – 1980

  This variant used a Rochester 2GC from 1976 to 78. In 1979, the more fuel-efficient Rochester Dual-Jet 2bbl carburetor replaced the older 2GC. This change also resulted in a drop in the horsepower rating to 130 hp, 125 for California emissions cars. All years had an 8.5:1 compression ratio.

BACK to Engine Variant

[] LG4

Years: 1980 – 1988

 The LG4 produced 150 hp - 170 hp and 240 lb·ft - 250 lb·ft. Introduced in 1978, the LG4 was essentially an LG3 with the addition of a 4-bbl carburetor. The engine saw a series of gradual improvements, increasing reliability, mpg, and power output through its production run. In 1981 (1980 for California models) Chevrolet added GM's new "Computer Command Control" (CCC) engine management system to the LG4 engines (excpet Canadian models). The CCC system included the electronic Rochester 4-bbl E4ME Quadra-Jet, where the primary side of the carburetor had the fuel metering controlled by computer. In 1983, Chevrolet replaced the cast iron intake with an aluminum version and utilized either 14014416 ("416") or 14022601("601") heads with int: 1.84/ exh: 1.50 valves, 58cc chambers, 178cc runners. For 1985, the 4-valve-relief, flat top pistons from the L69 were added to the LG4 which resulted in an increase in compression. Also added was a knock sensor to allow the "CCC" engine management system to compensate for the 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 from the 150 hp rating in 1984. For 1986, Chevrolet changed over to a 1 piece rear main seal engine block design to minimize leaks and warranty claims, however some early '86 blocks retained a 2 piece rear main seal.

 For 1987, Chevrolet once again made some revisions to increase overall reliability. An all-new electronic distributor design (with a smaller distributor cap) was used. The intake manifold to head bolt pattern was redesigned to improve gasket integrity - four of the center intake manifold bolts were drilled at 72 degrees instead of 90 degrees for the cast iron cylinder heads. Changes to the valve covers were also made. "ribbing" was added to the top of the valve covers to increase surface area, acting as a heat sink. To improve intake gasket sealing, the mounting bolts were relocated to the valve cover centerline, placing all sealing pressure evenly upon the mounting flange perimeter... thus these became known as "centerbolt valve covers", first introduced in 1985 on the LB4 4.3L V6 and the Corvette a year earlier (the aluminum cylinder heads used with the Vette were the first to have the centerbolt valve covers). Another improvement was utilization of a hydraulic lifter/roller camshaft on most '87 LG4's. Some early engines have lifter retainer provisions, but utilize the older, non-roller camshaft. 1987 would also be the last year for the LG4 production, however a run of LG4 engines was made to supplement the carry-over production for the 1988 Monte Carlo and the 1988 Chevrolet Caprice.

BACK to Engine Variant

[] LU5

Years: 1982 – late 1983

  The LU5 "Crossfire EFI 5.0L" featured a dual Throttle Body Injection set-up, based upon the original "Crossram Intake" supplied by Chevrolet for the 1969 Camaro Z28. Unlike, the original '69 version, Chevrolet did not place it in the trunk for owners to install. The system utilized a special version of GM's still-new "CCC" engine management system. Fuel was supplied by the two TBI units, set diagonally apart from each other, atop the unique, aluminum intake manifold. Unfortunately, the system was placed atop the basic LG4 and lacked any significant performance capability. The engine was originally planned for the long awaited '82 Camaro Z28, however due to a last-minute GM-mandated cancellation of Pontiac's 301 V8 production & Turbo 4.9L Project (T301), the Crossfire 305 was made available in the '82 Trans Am. A 350 cubic inch version was also used in the Corvette. Being fairly early into GM's electronic engine management development and electronic fuel injection programs, few dealerships had the technology, equipment, or properly trained mechanics capable of dealing with these engines. Compounding these problems were widely varying fuel quality standards, production issues, poor quality control by GM, & owners who tinkered with a system they did not understand. In a very short time, these engines obtained the notorious nickname; "Ceasefire Engine".

 To day, owners with these engines note that they are fairly reliable, and that a significant upgrade can be made by simply using the L69/LB9 TPI/L98 TPI exhaust manifolds/ exhaust systems... When combined with performance-built stock 305 heads w/larger valves or aftermarket heads, plus a camshaft upgrade, these engines can perform surprisingly well. Thanks mostly to a somewhat cult-like following, a number of aftermarket performance parts are also available through Crossfire-specialized manufacturers.

BACK to Engine Variant

[] L69

Years: late 1983 – 1988

  The L69 "High Output 5.0L" was released late into the 1983 model year. It was optional only in the "Firebird Trans Am" and "Camaro Z28" & "IROC-Z", and was Standard in the revived "Monte Carlo Super Sport" (no other GM models were available with this engine).

  The L69 features a compression ratio of 9.5:1, 4-relief flat top pistons, a unique & relatively aggressive stock camshaft, GM PN: 14088843* hydraulic flat tappet - duration @ .050": 202/206 - max lift: .403/.415 - 115 - idle: 650 rpm... *(not a camshaft taken from another Chevrolet engine). It also utilizes a performance-tuned "CCC" ECM/PROM, a knock sensor, a performance-tuned E4ME 750CFM Rochester Quadra-Jet 4 barrel carburetor, and a special, free-flowing exhaust system with large diameter exhaust manifolds, Y-Pipe, catalytic converter, and exhaust system, (The L69 F Body exhaust system components would be revised slightly and used again on the later LB9 305 & L98 350 TPI engines). Additionally, the engines came equipped with a functional cold air induction hood on the '83-'84 Trans Am H.O., a dual snorkel air cleaner assembly on the '83-'86 Camaro Z28/IROC-Z H.O., & '85-'86 Trans Am H.O., and a large, single snorkel on '83 -'88 Monte Carlo SS (also, rare optional dual snorkel in '87-'88), an aluminum intake manifold, high stall torque converter in the Monte SS and 1984 F-Body, or a lightweight flywheel on T-5 eqipped F-Body's, and all utilized 3.73 axle gears (3.42 Standard in '84 F-Body/ THM700R4/optional w/3.73:1). The Monte Carlo SS featured a special HD version of the THM200-4R also used in the Buick Turbo Regal/GN and Olds Hurst/Olds-442.

  The L69 engine produced 190 hp @ 4800 and 240 lb·ft of torque @ 3200 rpm. in the F-Body and was rated at 180 hp in the Monte SS.

BACK to Engine Variant

[] LE9

Years: 1981 - 1986

  The LE9 5.0 L (305 CID) was a truck/van/car version 4BBL 650CFM that also had a 9.5:1 compression ratio, the LM1 cam and 14010201 casting heads featuring 1.84/1.50" valves and 53 cc chambers. The engine made 165 hp @ 4,400 and 240 lb·ft @ 2,000 rpm.

BACK to Engine Variant

[] LB9

Years: 1985 - 1992

  The LB9 "Tuned Port Injection 5.0L" was introduced in 1985. At its core was the stout L69 shortblock and it utilized the same aggressive L69 camshaft profile. The induction system was unlike any system used previously by GM. It featured a large plenum made of cast aluminum, with individual runners made of tubular aluminum, feeding air to each cylinder. And each cylinder had its own fuel injector fed by a fuel rail mounted above each bank. In 1985, this engine was optional only in the "Camaro IROC-Z" and "Trans Am" equipped with the WS6 performance suspension. In the Corvette, a 350ci version of this engine, the L98, was released...it would be two years before the L98 would be offered in the F-Body. The LB9 was also available in the '87-92 GTA and Firebird Formula. 215 hp and 275 lb·ft and varied between 190 hp @ 275 lb·ft - 230 hp @ 300 lb·ft of torque over the years offered.

BACK to Engine Variant

[] L03

Years: 1987 – 1995



  The L03 produced 170 hp and 255 lb·ft of torque; 170 hp at 4,400 rpm and 275 lb·ft at 2,400 in 1993-1995 GM trucks. This engine used the TBI throttle-body fuel injection. It featured "swirl port" heads and served as the base engine in all C/K 1500 Series GMC/Chevrolet Trucks/Vans.

BACK to Engine Variant

[] L30

Years: 1996 - 2003

 The Vortec 5000 L30 is a V8 truck engine. Displacement is 5,013 cc, (305.9 cubic inches). Bore is 3.7 in stroke is 3.5 in. The compression ratio is 9.1:1. It is a based on the Generation I small-block from Chevrolet. It was replaced by the 4.8 L Vortec 4800 LR4 for the 2003 full-size vans. In van configuration it produces 220 hp net flywheel at 4,600 rpm and 290 lb·ft net flywheel torque at 2,800 rpm. The engine uses a hydraulic roller cam and high flowing, fast burn style vortec heads. Differences include bore and stroke, intake valve size, and smaller combustion chamber

BACK to Engine Variant

From Wikipedia, the free encyclopedia


 << 302 - HOME - HEADS INDEX - BLOCK INDEX - 307 >>