Is a 426 Hemi a Big Block or Small Block?

Chrysler eight cylinder engines came in big block or small block designs. For this reason some people wonder and ask, is a 426 Hemi a big block?

The 426 Hemi is a big block Chrysler engine first released in 1964 for racing. Its Hemispherical cylinder heads were designed to bolt on to a modified big block 426 wedge engine. The 426 street Hemi is also a big block and was produced for vehicles from 1966 to 1971.

This article will explain why the Hemi is a big block instead of a small block. In addition, I’ll take a look at why a big block is classified as such.

Is a 426 Hemi a Big Block or a Small Block?

When the first 426 Hemi Engine was invented and designed, Chrysler already had some Mopar big-block wedge engines in production.

One of those was the 426 max wedge engine, which was a big block engine. The difference between a big or small block Chrysler engine is not the cubic inches but its block dimensions.

When the Hemi Engine was in its planning stages, Chrysler opted to use the already existing 426 wedge block.

With some modifications to the wedge block, the Hemi Heads were designed and the wedge engine was adapted to fit the new Hemi heads.

When the designing was complete and the 426 Hemi was released by Chrysler for racing in 1964, it was released as a big block engine. This started a whole new car era.

What Makes a 426 Hemi a Big Block

Typically, a big block engine is larger and weighs heavier than a small block. Due to the larger size, bigger engine parts can be utilized.

Big blocks typically have larger bores and strokes. The cylinder heads used are also larger, so they can bolt onto the larger size block.

Due to the size of the heads, they can use bigger valves, intake and exhaust ports. The bigger engine parts can lead to more horsepower and torque.

It typically weighs more and has larger dimensions than a small block. The extra weight, which can be a negative in some ways, is offset by the extra horsepower.

The larger sized block engines also have bigger oil passages and systems.

There are no cubic inch displacements, dimensions or weight measurements which officially classifies an engine as a big block.

The newer engines are no longer classified as any particular size block, small or big, as they did in the earlier days. The current discussions typically say the cubic inch or liter only, including the package or kits available.

When I bought my first Mopar 38 years ago, it had a big block and manual steering. The extra weight made steering extremely difficult, especially when parallel parking. In the summer I would built a sweat, of course I didn’t have AC either.

Check out one of my latest articles, How to Identify a 426 Hemi.

I learned about 426 Hemis and Chrysler big blocks by reading Mopar books, articles, watching videos, talking to knowledgeable people and attending seminars. The research and knowledge I acquired has accumulated for 40 years.

If you have any questions or if you have more information you’d like to contribute, send us an email found on our contact page.

Read More Chrysler Hemi Articles

How Many Liters is a 426 Hemi?

Who Invented the 426 Hemi and Designed it

Where Was the 426 Hemi Built?

426 Hemi Specifications

Hemi Oil Capacity (Each Year and Model)

Evolution of the 426 Hemi big block.

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