AMC's first inline-six engine was a legacy model initially designed by Nash Motors; it was discontinued in 1965.

This family of six-cylinder engines was also manufactured by Vehículos Automotores Mexicanos and included a version available only in Mexico.

American Motors' first straight-six engine was the 196 cubic inch (195.6 cu in (3.2 L)) six produced from 1952 through 1965, initially as a flathead (L-head) side-valve, and later an overhead valve (OHV) version.

[3] American Motors introduced a die-cast aluminum block version of the OHV 195.6 cu in (3.2 L) engine in 1961 and produced it through 1964.

This AMC and Jeep engine's "longevity and reputation as a rugged, reliable powerplant for off-road vehicles" has put it ahead of Chrysler's Slant-6.

[5] Called the "Torque Command" when first introduced, the 232 cu in (3.8 L) inline six was AMC's first modern six-cylinder engine.

[6] Road tests by Consumer Reports described the new powerplant as "a very smooth and quiet engine, which should give good performance.

"[7] To commemorate the engine's May 1964 launch, a total of 2,520 "Typhoon" versions were made based on the Rambler Classic hardtop body.

"[11] For the first Indy attempt, Navarro designed a fuel-injection system, a unique head, and a single turbo to achieve 550 hp (410 kW; 558 PS) at 6000 rpm.

[18] An auction was held on 14 July 2005, to clear the remaining contents of the Navarro Engineering shop in Los Angeles.

[19] A private collector purchased a complete Navarro 700 hp (522 kW; 710 PS) 199 cu in (3.3 L) engine for $15,000.

[21] Air conditioning was available only with the older 196 engine in the American models because there was not enough space for the compressor with the longer 232.

[21] Changes for the 1976 model year included fuel economy improvements that reduced emissions and warmup time.

Output for 1972 Rambler American Rally model (gross): Engine dimensions: The 258 cu in (4.2 L) was produced from 1971 through 1990.

For 1981, as part of a weight reduction program (aluminum intake manifold, plastic rocker arm cover), the crankshaft was changed from a twelve counterweight design to four, saving approximately 20 pounds (9.1 kg).

The 282 cu in (4.6 L) engine was produced by AMC's Mexican subsidiary Vehículos Automotores Mexicanos (VAM) beginning in 1971 through 1986.

All units were produced in VAM's engine plant located in Lerma, Estado de México.

in just 26 months using many off-the-shelf components while featuring, among others, additional strength, improved combustion chamber, port setup, and cam profile.

[31] A Motor Trend long-term test of a 1997 Cherokee XJ noted "this long-lived OHV powerplant has a reputation for getting people where they need to go" as well as "much love expressed by owners for the torquey 4.0-liter/190-horsepower inline six.

[33][34] The vibration dampener (harmonic balancer) usually gives out after 300,000 miles, where it is common for the rubber insulation to deteriorate where a service replacement is warranted.

[24] A knock sensor allowed the ECU to control spark advance in response to fuel octane and engine load.

RENIX systems also have no permanent memory for diagnostics codes, thus making diagnosing intermittent problems more difficult.

Chrysler also enlarged the throttle body and redesigned the intake and exhaust manifolds for more efficiency, and the fuel injectors were replaced with higher flow units.

Early 0331 heads are prone to cracking, causing coolant to contaminate the oil, which can lead to catastrophic engine failure.

Output:[39] The 4.0 L engine was discontinued at the end of the 2006 model year, replaced in the redesigned 2007 JK Jeep Wrangler by Chrysler's 3.8 L OHV V6, which originated in the company's minivans.

1964–1970: 1971–2006: The deck height of the AMC six-cylinder block was increased by 1⁄8 in (3.2 mm) (half the rod length difference) in 1971 to allow for the longer stroke required for the 258.