Mopower Garage

Published by Christopher J. Holley | Mopar History & Tech | June 2025

By the late 1960s, the muscle car wars were in full swing. Big blocks ruled the drag strips, and every major automaker had a contender. However, Chrysler noticed something missing in its lineup, a true high-performance small-block V8. What came next was one of the most respected street engines of the era, the 340.

Follow along as we explore why Chrysler created the 340 cubic-inch V8 and what made it a legend among Mopar enthusiasts.

The Performance Gap Chrysler Needed to Fill

In the mid-’60s, Chrysler’s small-block engines, like the 273 and the 318, were solid and dependable but not precisely known for laying down rubber. Meanwhile, GM and Ford were having success with high-winding small blocks like the Chevy 302 Z/28, 327 Chevy II, and the Ford Hi-Po 289. Chrysler needed something to compete in the lightweight, affordable performance car space.

So, in 1968, they rolled out an answer: the 340 V8. But this was not just a bored-out 318. Chrysler engineered the 340 as a performance engine from the ground up.

Built to Rev, Built to Run

Right from the factory, the 340 was packed with go-fast parts:

• Big valve heads (X or J heads with 2.02″ intake and 1.60″ exhaust valves)
• Dual-plane intake manifold
• High-lift camshaft
• 10.5:1 compression ratio
• Four-barrel Carter AVS carb
• Forged steel crankshaft (on early models)
• Windage tray and beefy internals

Officially, it was rated at 275 horsepower, but most agree it was underrated, especially when it ran neck-and-neck with 383s and 396 Chevys on the street.

A-Body Rockets: Small Block, Big Attitude

The 340 perfectly matched Chrysler’s A-body cars, compact platforms like the Dodge Dart Swinger, GTS, Plymouth Duster, and Barracuda. Lightweight and affordable, these cars became serious street machines when paired with the new small block.

The Duster 340 emerged as an affordable street icon.  It had the power to run with big-block cars but without the insurance penalty or front-end weight. The Duster 340 could hold its own in the quarter mile and still handle well enough for spirited street driving.

Trans Am Racing Influence

There was more than just a street cred behind the 340’s development. Chrysler also had racing on its mind, particularly SCCA Trans Am racing, which had a 305 cubic inch limit.

While Chrysler never dominated Trans Am like Ford or Chevy, the idea of a de-stroked 340 for track use was in play. And the engineering that went into making the 340 so robust came in part from that racing ambition.

Beating the Insurance Game

By 1970, insurance companies were cracking down on muscle cars, especially big blocks with 400+ cubic inches. The 340 gave buyers a way to get serious performance without sky-high premiums. It looked good on paper—just a small V8—but it ran like a big block.

Savvy buyers figured it out fast: you did not need a 440 to go fast if you had a well-tuned 340 under the hood.

Mopar Legacy Sealed

The 340 quickly earned a loyal following among racers, street drivers, and young enthusiasts. It was dependable, rev-happy, and responded well to modifications. Even today, it is regarded as one of Chrysler’s most well-balanced performance engines.

When the 360 replaced it in 1974, many Mopar purists felt the era of the “real” small block had ended. The 340 was not just about cubes but about attitude, engineering, and hitting the sweet spot between power and weight.

Final Thoughts

Chrysler did not build the 340 just to fill a spec sheet. They built it to win back the streets, compete in racing, and offer serious power in small packages. And for a few glorious years, it did precisely that.

Whether you owned a Duster 340, a Dart GTS, or a ‘Cuda with the small-block screamer, one thing was clear, you did not need a HEMI to haul.