1980 California 305 Engine
photo:corvsport gallery

1980 LG4 305CI “California” V8 Engine Guide: Specs, Features, & More

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When already stringent emissions standards are further exacerbated by the state of California’s unfathomably-strict environmental mandates, a stifling set of circumstances are posed for the majority of the nation’s automotive manufacturers. This was the reality faced by those hoping to market performance vehicles of any make and model, on the west coast, during the late 1970s and early 1980s.

General Motors was not immune to this hardship and found itself facing a critical question of sorts. Should the industry giant forgo the sale of Corvettes in California during the 1980 model year, or attempt to rectify a troubling situation. In the end, buyers in California would indeed be able to purchase a Corvette in 1980, albeit with a variation of the same engine that was offered in Chevrolet’s passenger cars of that era, the 305 cubic-inch V8.

LG8 305CI History

White 1980 California Corvette
photo: time.com

The Corvette line was dealt an enormous blow in 1970, with the passage of the Clean Air Act. This legislation spawned oversight that would ultimately govern the emissions output of all vehicles manufactured and sold in the United States.

Prior to the implementation of such mandates, consumers could purchase a Corvette with their choice of several engines, including a number of both big-block and small-block offerings. However, as if overnight, the number of engines listed on the Corvette’s options sheet began to dwindle.

The big-block beasts that once resided beneath the Corvette’s hood were the first powerplants to suffer, completely disappearing from production by 1974. At the same time, GM began detuning many of its small-block offerings, in a bid to reach compliance. Doing so was seen as a way to buy time until subsequent technological advancements came to pass.

In the vast majority of cases, the implementation of these changes was enough to keep the Corvette flying below the radar. However, in California, where the era’s emissions standards far exceeded those that were federally mandated, the Corvette was still under-fire.

The biggest problem faced by the Corvette design team was the 350 cubic-inch small-block’s irreconcilable failure to meet California’s emissions standards. However, before pulling the plug on Corvette sales in California during the 1980 year model, a compromise of sorts was reached.

The Corvette sales would indeed continue in California. However, the cost associated with this decision was quite steep. The legendary 350 cubic-inch small-block would not be available to consumers in the state. In the engine’s place would be GM’s 305 cubic-inch small-block, which had first been introduced in 1976, as GM’s powerplant of choice for the company’s base-model sedans.

LG4 305CI Specifications and Technical Configurations

1980 California 305 engine
photo: topclassiccarsforsale.com

The 1980 LG4 featured a cast-iron engine block, which housed a nodular-iron crankshaft of an identical casting number to that used in the 350CI small-block. However, the 305 cubic-inch LG4’s crankshaft was lighter in weight and featured smaller counterweights. This crankshaft was of a two-bolt main construction.

The 305CI V8’s crankshaft was fitted with General Motors’ “pink” connecting rods, so named for the pink paint markings that they carried. These connecting rods were fitted with dished-top pistons at their opposing ends, which reciprocated within 3.736” diameter cylinder bores, with a stroke of 3.48”.

The LG4’s featured a relatively mild hydraulic lifter camshaft and was fitted with a pair of standard cast-iron cylinder heads. These heads featured valves that measured 1.72” (intake) and 1.50” (exhaust), respectively. The LG4 operated on a rather subdued 8.5:1 compression ratio.

The “California” 305CI V8 was supplied fuel through a modified four-barrel Rochester Quadrajet carburetor, which was controlled by GM’s Command Control System (CCC). This system also included the use of two closed-loop oxygen sensors. In many ways, the LG4’s computer-controlled carburetor pre-dated later TBI systems to come.

All things considered, the LG4 mustered only 180 horsepower and was largely unremarkable in almost every regard. To make matters worse, the LG4 could only be paired with an automatic transmission.

Yellow 1980 California Corvette
Photo: Corvsport gallery

LG4 305CI Specs Index

  • Horsepower: 180 hp @ 4,200 rpm
  • Torque: 255 lb.-ft @ 2,000 rpm
  • Compression Ratio: 8.5:1
  • Displacement: 305CI (5.0L)
  • Cylinder Bore: 3.736” (94.89 mm)
  • Stroke: 3.48” (88.39 mm)

LG4 (305CI) Additional Uses

The 305 cubic-inch LG4 spent only one year beneath the Corvette’s hood, before eventually being replaced the following year when those at GM finally found a way to bring the 350 cubic-inch small-block into compliance with California emissions standards. This engine would come to be known as the L81.

However, the LG4 would ultimately serve as the emissions-compliant engine of choice for numerous GM models throughout the 1980s, including the Chevrolet Monte Carlo and Caprice. Throughout its production run, the LG4 would undergo a number of subsequent revisions, many of which were aimed at squeezing out additional horsepower.

The 305 Cubic-Inch “Corvette” Small-Block

Even today, many Corvette enthusiasts fail to acknowledge the existence of a 305 cubic-inch small-block powered Vette. This, of course, is for good reason. One would be hard-pressed to have described the LG4 as little more than anemic, carrying only a slight bit higher output than the Corvette’s original “Blue-Flame” Stovebolt-Six from some 30-years prior.

However, the story of the 305CI LG4 is indeed a noteworthy entry in the history of America’s sports car. In many ways, a desire to overcome stifling emissions standards of the era led to much of the ingenuity that is now seen beneath the Corvette’s hood. For better or for worse, the 1980s were a time in which even the nation’s most revered performance car could not escape the politics of the day.