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Big block and small block differences

Several different engine options were available during the Corvette C3 generation. One of the debates between the big block and the small block is which one is better. Even from the name, you can tell the difference between them, the big block is physically bigger, which therefore allows better cooling, and larger cylinders -> more power and torque.

The disadvantage of the big block is the weight compared to the small block, which affects on handling and acceleration of the car. Big blocks are also more valuable, more expensive to repair, and consume more fuel.

Starting in 1975, the C3 Corvette only had small block engines, and in its final years of production, the engine range was very limited. When comparing horsepower, it should be noted that in 1972, GM changed the way they reported engine horsepower.

On Decoder's main page, you can learn more about the available engine options by model year.

Corvette C3 big blocks

427 cu in (1968 - 1969)

In the first years of the C3 generation (1968-1969), the big blocks (427 cu in) were powerful as in the previous generation (390-435 hp), the more powerful models used 2-throat carburetors made by Holley, while the others used Rochester Quadrajets.

454 cu in (1970 - 1974)

In 1970, the big block grew to 454 cu in. Its output ranged from 289 horsepower to 425 horsepower, but in its last three years of production, the engine was only available as a 270-275 horsepower version.


X 1969 Chevrolet Corvette C3 V8 L68 Quat-Power 427 cui

Corvette C3 small blocks

327 cu in (1968 - 1969)

The 327 cu in engine that was also in use in the C2 generation was in production only in 1968 and 1969 (300 and hp), after that its displacement was increased to 350 cu in.

350 cu in (1970 - 1982)

The 350 cu in was the most common Corvette C3 engine and was used throughout the third generation, except for the first two years of production. It's a very good engine that can easily be modded for more power if desired.

305 cu in (1980)

In 1980, stricter emission restrictions forced the introduction of a 305 cu in engine in the Corvette in California. This one-year exception produced only 185 hp, the next year engineers got a 350 cu in engine to meet emissions requirements.

L48 and L82

Between 1973 and 1980, two different versions of the 350 cu in were offered. The basic model was called L48, and the performance version was called L82. The power difference varied slightly every year, but the L82 was typically about 40 hp more powerful than the L48 engine.

L48 and L82 share the same block, but the L82 included many components to produce more power. The L82 had an aluminum intake (L48 in 1980), four-bolt mains, larger heads and valves, forged steel crank and different pistons than the L48.



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Last Updated 12/28/2022