Did they make a 400 big block?

Yes, Chevrolet did produce a 400 cubic inch (6.6 liter) big block V8 engine. The 400 big block was a popular and powerful engine option for many Chevrolet vehicles in the 1960s and 1970s.

The 400 Big Block Engine

The 400 big block was part of Chevrolet's line of big block V8 engines, which were known for their large displacement and high horsepower output. The 400 big block was introduced in 1970 and was produced until 1980. It had a bore of 4.125 inches and a stroke of 3.75 inches, giving it a total displacement of 400 cubic inches (6.6 liters).

The 400 big block was available in a variety of power ratings, with horsepower ranging from around 260 to 300 horsepower, depending on the specific engine configuration and year. It was used in a wide range of Chevrolet vehicles, including the Chevelle, Impala, Caprice, and Corvette.

Why Was the 400 Big Block Popular?

The 400 big block was popular for several reasons:

• Power and Performance: The large displacement and high horsepower output of the 400 big block made it a powerful and responsive engine, providing excellent acceleration and towing capacity.


• Durability: The big block design of the 400 engine made it a robust and reliable powerplant, able to withstand high-performance use and heavy-duty applications.


• Availability: The 400 big block was a widely available engine option, making it easy for consumers to find and purchase vehicles equipped with this powerful V8.

The 400 big block's combination of power, durability, and availability made it a popular choice among Chevrolet enthusiasts and performance-oriented drivers during the 1960s and 1970s.

Did Chevy ever make a 400 big block?

No, Chevy did not make a "400" big block, but they did make a large, powerful 402 cubic inch big block and a 400 cubic inch small block engine around the same time, which caused some confusion. From 1971 to 1973, Chevy sometimes used "400" in its advertising for the 402 big block, which was officially known as the "Turbo-Jet 400" (while the 400 small block was the "Turbo-Fire 400"). 
You can watch this video to learn about the history of the Chevy small-block 400: 56sRare Classic Cars & Automotive HistoryYouTube · Aug 31, 2023
Chevrolet's 400 cubic inch engines 

• 400 Small Block: This engine was produced from 1970 to 1980 and was the largest displacement for the small block family. It was designed for low-end torque, making it well-suited for heavy cars and trucks. 
• 402 Big Block: This was the actual displacement of the big block engine that was sometimes marketed as a "400". It was part of the Mark IV big block V8 line, produced from 1970 to 1972. 

Why the confusion?

• In marketing materials, especially from 1971-1973, Chevy used the "400 Turbo-Jet" designation for the 402 big block to avoid confusion with the smaller engines, but it was still a confusing marketing decision.
• The existence of two 400 cubic inch engines in different engine families (one small block and one big block) was a source of confusion for car enthusiasts. 

Is there a 400 big block?

Yes, a "400" engine is often considered a big block, but it depends on the manufacturer, as some had a 400 cubic inch big block (like Mopar and Buick), while others had a 400 cubic inch small block or a similar engine that was larger than a small block but not a traditional big block (like Ford's 400, sometimes called a "medium block"). The distinction is based on the physical dimensions of the engine block, not just the cubic inch displacement.
 
Examples of 400 "big block" engines

• Mopar: The 400 cubic inch engine was a member of the B-series big block engine family, replacing the 383 in 1972. 
• Buick: The 400 cubic inch engine was a part of Buick's big-block engine lineup and was found in models from 1967–1969. 

Examples of 400 engines that are not considered big blocks 

• Ford: The 400 cubic inch engine is a unique case. It is physically larger than a small block, but smaller and lighter than Ford's larger 429 and 460 engines. It is sometimes called a "medium block". 
• Chevrolet: While Chevrolet had big blocks like the 396, 402, 409, and 427, the 400 was not produced as a big block. 

Did Ford make a 400 big block?

No, the Ford 400 was not a traditional big block, but rather a unique engine that shared the bore spacing and bell housing pattern of Ford's big blocks, though it was part of the 335-series family alongside the 351 Cleveland and the 351M (Modified). It was built with a taller deck and longer stroke, making it a "stroker" version of the 351 Cleveland. This design made it a powerful and unique engine, often considered in its own category between small blocks and big blocks.
 
Ford 400 engine characteristics

• Engine family: The 400 belongs to the 335 engine family, which also includes the 351 Cleveland and the 351M. 
• Bore and stroke: It features a 4.00-inch bore and a 4.00-inch stroke, giving it a 400 cubic inch displacement. 
• Deck height: The deck height is taller than the 351 Cleveland, which is why it is sometimes called a "tall deck" engine. 
• Bell housing: It uses the same bell housing bolt pattern as Ford's 429/460 big block engines, making it compatible with big block transmissions like the C6. 
• Cylinder heads: It shares cylinder heads with the 351 Cleveland and 351M engines. 
• Performance: In stock trim, the 400M produced around 160–180 horsepower, but was known for its low-end torque, making it ideal for towing and hauling. With modifications like a four-barrel carburetor, camshaft, and intake manifold, it could be built to produce significantly more power. 
• Availability: It was produced from 1971 to 1982 and was found in many larger Ford cars, trucks, and vans during that time. 

This video explains the Ford 400 engine and its characteristics: 42sThe Junkyard NecromancerYouTube · Jan 24, 2025
Is it a small block or big block?
While it shares some characteristics with both, the 400 is most accurately described as a unique engine that falls into its own category. 

• It's not a small block because of its tall deck and longer stroke, but it's not a true big block due to its bore spacing. 
• It's a "stroker" version of the 351 Cleveland, meaning it has a longer stroke to achieve its higher displacement. 
• It's often called a "400M" because it shares the block with the 351M engine. 

Did Dodge make a 400 big block?

The 400 was used in car, truck, and motorhome chassis. Horsepower and torque ratings gradually declined through the years because of the addition of more federally mandated emissions controls, until all Chrysler passenger vehicle big-block production ceased in 1978.