Editing AMC straight-6 engine

{{Short description|Series of I6 engines built by American Motors and Chrysler}}
{{Main|List of AMC engines}}
{{Use dmy dates|date=April 2024}}

{{Infobox automobile engine
| name = AMC Straight-6 engine
| image = 1973 AMC Matador wagon sx-Cecil'10.jpg
| manufacturer =  {{ubl | [[American Motors Corporation]] (1964-1987) | [[Chrysler Corporation]] (1987-2006) }}
| production = 1964–2006
| configuration = [[Naturally aspirated]] [[Straight-six engine|Straight-6]]
| block = [[Cast-iron]]
| head = [[Cast-iron]]
| valvetrain = [[Overhead valve engine|OHV]] 2 valves x cyl.
| fueltype = [[Petrol engine|Gasoline]]
| fuelsystem =  {{ubl | [[Carburetor]] | [[Multi-port fuel injection]] }}
| coolingsystem = [[Radiator (engine cooling)|Water-cooled]]
| management =  {{ubl | [[AMC Computerized Engine Control|AMC CEC]] | [[Renix]] or [[Mopar]] (manufactured by [[Siemens]]) }}
| displacement = {{ubl |{{cvt|199|CID|L|1}}|{{cvt|232|CID|L|1}}|{{cvt|242|CID|L|1}}|{{cvt|252|CID|L|1}}|{{cvt|258|CID|L|1}}|{{cvt|282|CID|L|1}} }}
| bore = {{ubl | {{cvt|3.75|in|mm|1}} | {{cvt|3.875|in|mm|1}} | {{cvt|3.91|in|mm|1}} | {{cvt|3.917|in|mm|1}} }}
| stroke = {{ubl | {{cvt|3|in|mm|1}} | {{cvt|3.414|in|mm|1}} | {{cvt|3.4375|in|mm|1}} | {{cvt|3.5|in|mm|1}} | {{cvt|3.895|in|mm|1}} }}
| power = {{cvt|129–200|hp|kW PS|0}}
| torque = {{cvt|216–280|lbft|Nm|0}}
| weight = {{cvt|483|lb|kg}} (4.0&nbsp;L engine)
| compression = 7.7:1, 8.0:1, 8.5:1, 9.5:1
}}

The '''AMC straight-6 engine''' is a family of [[straight-six engine]]s produced by [[American Motors Corporation]] (AMC) and used in passenger cars and [[Jeep]] vehicles from 1964 through 2006. Production continued after [[Chrysler]] acquired AMC in 1987.

American Motors' first inline-six engine was a legacy model initially designed by [[Nash Motors]]; it was discontinued in 1965. A completely new design was introduced by AMC in 1964. The engine evolved in several displacements and underwent upgrades. [[Vehículos Automotores Mexicanos]] (VAM) also manufactured this family of six-cylinder engines, including a version available only in Mexico.

A new 4.0&nbsp;L engine was introduced by AMC in 1986 and became the final version of AMC inline sixes. It is regarded as one of the best 4x4 and off-road engines. This engine was produced by Chrysler through 2006.

Among "classic American engines, the AMC straight-six stands as a testament to smart engineering and enduring performance".<ref>{{cite web|url= https://automotiveamerican.com/2024/11/27/the-amc-straight-six-a-long-running-story/
|title=The AMC Straight Six, a Long Running Story |date=27 November 2024 |website=automotiveamerican.com |access-date=2 April 2025}}</ref>

==Predecessors==
{{Main|Nash Rambler straight-six engine}}
[[File:AMC 196.jpg|left|thumb|A 1964 Rambler American with a 195.6 OHV engine]]

The straight-six engine lineage at AMC goes back to [[Nash Motors]]. An economy-focused engine debuted in the 1941 [[Nash 600|Nash Ambassador 600]] model.<ref name="Trendsetter">{{cite web |last1=McGuire |first1=Bill |title=Trendsetter: The 1941 Nash 600 |url= https://www.macsmotorcitygarage.com/trendsetter-the-1941-nash-600/ |website=macsmotorcitygarage.com |date=16 December 2021 |access-date=17 April 2024}}</ref><ref>{{cite web |last1=Perschbacher |first1=Gerald |title=Merger Mania: Nash and Hudson form AMC |url= https://www.oldcarsweekly.com/features/merger-mania-nash-and-hudson-form-amc |work=Old Cars Weekly |date=11 January 2021 |access-date=17 April 2024}}</ref> Its initial displacement of {{cvt|172.6|CID|L|1}} was subsequently increased to {{cvt|184|CID|L|1}} and finally to {{cvt|195.6|CID|L|1}} in 1952. 

After Nash merged with [[Hudson Motor Car Company|Hudson]] to form AMC in 1954, efforts continued to enhance performance and meet evolving market demands. The engine's architecture underwent a significant transformation for the 1956 model year, transitioning from a [[Flathead engine|flathead]] (L-head) side-valve configuration to an [[overhead valve]] (OHV) design.<ref name="RamblerLore">{{cite web |last1=Jennings |first1=Tom |last2=Swygert |first2=Frank |title=Rambler 195.6 ci overhead valve six — Brief History |url= https://www.ramblerlore.com/AMC/195.6ohv/index.html |website=ramblerlore.com |date=3 December 2023 |access-date=17 April 2024}}</ref> This modernization aimed to improve engine efficiency and power output.<ref name="RamblerLore"/> The flathead version was reintroduced in 1958, serving as the base economy engine for the newly launched [[Rambler American]] compact car.<ref name="RamblerLore"/> This dual-engine strategy persisted until 1965, catering to performance-oriented and economy-minded consumers.<ref name="RamblerLore"/>

To reduce vehicle weight and enhance fuel efficiency, AMC introduced a die-cast aluminum block version of the OHV {{cvt|195.6|CID|L|1}} engine in 1961.<ref>{{cite web|url= http://amcrc.com/feature/alum_eng.html |title=America's First Die-Cast Aluminum Engine (from: (1993 Rambler Reader, Vol. 14 No. 2) |website=amcrc.com |access-date=17 April 2024}}</ref> This innovative approach resulted in a significant weight reduction, with the aluminum engine weighing  {{cvt|380|lb|kg}}, compared to its cast-iron counterpart's {{cvt|460|lb|kg}}.<ref name="Magnante">{{cite web|url= https://www.hotrod.com/features/ccrp-0608-junkyard-crawl-aluminum-block/ |title=Junkyard Crawl - Alloy Granny |first=Steve |last=Magnante |date=21 September 2006 |work=Hot Rod |access-date=2 April 2025}}</ref> This aluminum engine was produced through 1964, showcasing AMC's engineering prowess and willingness to experiment with advanced materials.<ref name="Magnante"/>

While not known for high performance, this engine was known for reliability. This engine was also used in marine applications.

{{clear left}}

=={{anchor|232|232 (Modern Era)}} Modern Era ==
[[File:1968 Rambler American wagon-engine-MDshow.jpg|thumb|Engine bay of a 1968 [[Rambler American]] ]]

American Motors introduced a groundbreaking inline-six engine in 1964. It featured a short-stroke design and a robust seven-[[main bearing]] crankshaft with an overall design to provide good torque at low RPMs. This engine, a testament to AMC's engineering, enjoyed a remarkable production run that continued under AMC and Vehículos Automotores Mexicanos (VAM) as well as by Chrysler until 2006. Its enduring legacy and reputation as a reliable and rugged engine, particularly in off-road applications, has solidified its position as superior to Chrysler's Slant-6.<ref>{{cite web|title=Chrysler Slant-6 Vs. AMC/Jeep Inline-6: Which Is The Better Engine? |url= https://www.slashgear.com/1557060/chrysler-slant-6-vs-amc-jeep-inline-6-which-engine-is-better/ |first=Ron |last=King |date=12 April 2024 |website=slashgear.com |access-date=23 April 2024}}</ref>

Initially marketed as the "Torque Command" engine, the {{cvt|232|CID|L|1}} inline-six represented AMC's first genuinely modern six-cylinder engine.<ref>{{citation |first=David V. |last=Potter |first2=George F |last2=Leydorf, Jr. |first3=Robert L. |last3=Lawler |title=The new Rambler Six Engine — Torque Command 232 (Technical Paper 640276) |publisher=Society of Automotive Engineers |date=June 1964 |doi=10.4271/640276}}</ref> Road tests conducted by ''Consumer Reports'' lauded the engine as "a very smooth and quiet engine, which should give good performance."<ref>{{cite magazine |title=The 1965 Autos |magazine=Consumer Reports |date=April 1965 |volume=30 |page=198}}</ref>

To commemorate the engine's launch in May 1964, AMC produced 2,520 special "Typhoon" editions based on the [[Rambler Classic]] two-door hardtop.<ref>{{cite magazine |url= https://books.google.com/books?id=rC0DAAAAMBAJ&q=Rambler+Typhoon&pg=PA66 |title=Rambler blows in with Typhoon |magazine=Popular Science |date=June 1964 |page=66 |volume=184 |issue=6 |via=Google Books |access-date=17 April 2024}}</ref> These distinctive vehicles featured the {{cvt|145|hp|kW PS|0}} 8.5:1 compression ratio engine, a striking Solar Yellow exterior with a Classic Black roof, and "Typhoon" badging in place of the standard "Classic" script. Notably, all other Rambler Classic options, except alternative engine choices, were available on the Typhoon edition.<ref>{{cite web |author=((Auto editors of ''Consumer Guide'')) |title=How Rambler Cars Work: 1963, 1964 Rambler Cars |website=auto.howstuffworks.com |url= https://auto.howstuffworks.com/rambler-cars.htm#pt3 |date=15 June 2007 |access-date=17 April 2024}}</ref>

For the 1965 model year, the 232 engine superseded the aging Nash {{cvt|195.6|CID|L|1}} OHV inline-six in the Classic and Ambassador models. This marked the return of a six-cylinder engine in the Ambassador line since 1956, reflecting AMC's commitment to offering a wider range of powertrain options.<ref>{{cite web|url= https://auto.howstuffworks.com/1965-1966-rambler-ambassador.htm |author=((Auto Editors of "Consumer Guide")) |title=1965-1966 Rambler Ambassador |date=23 October 2007 |website=auto.howstuffworks.com |access-date=2 April 2025}}</ref>

In 1966, AMC expanded its six-cylinder lineup by introducing the {{cvt|199|CID|L|1}} version of the 232 engine. This smaller variant replaced the OHV and L-head {{cvt|195.6|CID|L|1}} engines across AMC's passenger car lineup.

Both the 199 and 232 engines shared a {{cvt|3.75|in|mm|1}} bore, differing only in stroke: {{cvt|3|in|mm|1}} for the 199 and {{cvt|3.5|in|mm|1}} for the 232. The 199 engine was discontinued in 1970, while the 232 continued production alongside the larger {{cvt|258|CID|L|1}} engine, which the increase in displacement was achieved by employing a {{cvt|3.895|in|mm}} stroke crankshaft and a slightly taller engine block.

More stringent [[Vehicle emissions control|emission control regulations]], coupled with the growing weight of vehicles due to [[Automobile safety|safety]] mandates, led to a gradual decline in engine power output, ultimately resulting in the discontinuation of the 232 in 1979.

[[File:1966 Rambler Classic 770 conv six white FS-m.jpg|thumb|Standard 232 in a 1966 [[Rambler Classic]]]]
[[File:1971 AMI Rambler Gremlin AnnMD engn3.jpg|thumb|Engine bay of 1971 [[Australian Motor Industries|AMI]] Rambler Gremlin]]
[[File:1975 AMC Hornet 232 I6 engine.JPG|thumb|Engine bay of a 1975 [[AMC Hornet]] with a 232]]

===199===
The {{cvt|199|CID|L|1}} engine was produced from 1965 through 1970.

====Navarro Indy====
Barney Navarro selected the 199 AMC engine to power a race car for the [[Indianapolis 500]]. Navarro had previously applied turbocharging to a variety of engines that led to the 199 engine's Indy-related application "based on a Stone-Age-strong Nash 6."<ref>{{cite web|url= https://www.motortrend.com/features/barney-navarro-982-1647-112-1/ |title=Barney Navarro (Originally published in the May 1998 issue of Hot Rod magazine) |date=1 January 2023 |work=Motor Trend |access-date=23 April 2024}}</ref>

This engine had not been used in an [[IndyCar]]. However, Navarro selected it "due both to its strong bottom end and thick cylinder walls."<ref name="unconventional">{{cite web|url= https://www.hemmings.com/stories/article/barney-navarro |title= Barney Navarro — Unconventional thinking and hard work put his products in the record books |first=Daniel |last=Strohl |date=23 September 2018 |work=Hemmings |access-date=23 April 2024}}</ref> For the first Indy attempt, Navarro designed a fuel-injection system, a unique head, and a single turbo to achieve {{cvt|550|hp|kW PS|0}} at 6000&nbsp;rpm. This was with the stock block featuring seven main bearings and large journal sizes, while the second block was drilled for four-bolt caps.<ref>{{cite web|url= https://www.inliners.org/ubbthreads/ubbthreads.php?ubb=showflat&Number=76243 |title=Thinking about hot rodding an AMC 199 |date=6 November 2013 |first=Ton |last=Jenkins |website=inliners.org |access-date=23 April 2024}}</ref> Successive engines incorporated double turbochargers to produce {{cvt|640–700|hp|kW PS|0}}.<ref>{{cite web|url= https://www.ramblerlore.com/AMC/Navarro-turbo-motor/index.html |title=Barney Navarro-built Rambler turbo Indy motor |first=Tom |last=Jennings |website=ramblerlore.com |access-date=17 April 2024}}</ref><ref>{{cite web|url= https://www.motortrend.com/news/0903cct-h-and-h-flatheads-navarro-racing-equipment/ |title=H&H Flatheads & Navarro Racing Equipment — Classic Life |first=John |last=Gilbert |date=1 March 2009 |work=Motor Trend |access-date=23 April 2024}}</ref>

Navarro fielded a 1964 Watson car with the AMC 199 engine for three years at the Indianapolis 500.<ref>{{cite web|url= https://www.oldracingcars.com/watson/64/ |title=Watson 1964 Indy car-by-car histories — 'the Ward car' |date=3 May 2023 |website=oldracingcars.com |access-date=23 April 2024}}</ref> However, the #50 Navarro-Rambler never qualified due to problems with drivers and with the suspension of the cars.<ref name="unconventional"/><ref>{{cite web|url= http://www.navarroengineering.com/about_barney.html |title=Barney Navarro |website=navarroengineering.com |archive-url= https://web.archive.org/web/20061209083433/http://www.navarroengineering.com/about_barney.html |archive-date=9 December 2006 |access-date=23 April 2024}}</ref> The car was also entered at the 1971 IndyCar "[[Autódromo Ciudad de Rafaela|Rafaela]] 300" season opener in Argentina. This was the car's fourth actual race start, and it began at 19 on the starting grid. Dave Strickland drove it for 45 laps.<ref>{{cite web|url= https://forums.autosport.com/topic/75917-rafaela-300-and-the-1971-usac-season/ |title=Rafaela 300 and the 1971 USAC season |date=January 2005 |website=autosport.com |access-date=23 April 2024}}</ref> This car was then driven by Les Scott in practice for the 1971 Indy 500 race.<ref name="notes"/> The following year, another attempt to qualify was with [[Leon Sirois]] as the driver.<ref name="notes">{{cite web|url= https://www.oldracingcars.com/indy/results/1965/indianapolis500/ |title=Indianapolis 500 — Indianapolis Motor Speedway (Notes on the cars: #29) |website=oldracingcars.com |access-date=23 April 2024}}</ref>

An auction was held on 14 July 2005, to clear the remaining contents of the Navarro Engineering shop in Los Angeles.<ref name="auction"/> A private collector purchased a complete Navarro {{cvt|700|hp|kW PS|0}} {{cvt|199|CID|L|1}} engine for $15,000.<ref name="auction">{{cite web|url= https://www.ramblerlore.com/AMC/Navarro-Indy-motor/index.html |title=Barney Navarro-built Rambler turbo Indy motor |first=Tom |last=Jennings |website=ramblerlore.com |access-date=23 April 2024}}</ref>

{{Hidden begin
|title = Applications:
|titlestyle = background:#88FF88; text-align:left;
|bodystyle = text-align:left;
}}
* [[Rambler Classic]] (1965–1966, fleet cars only)
* [[Rambler American|Rambler American/AMC Rambler]] (1965–1969)
* [[AMC Hornet]] (1970)
* [[AMC Gremlin]] (1970)
* VAM Rambler American (mid 1965–1969) U.S. equivalent — AMC Rambler American and AMC Rambler sedans
* VAM Camioneta Rambler American (mid 1965–1967) U.S. equivalent — AMC Rambler American wagon
{{Hidden end}}

===232===
The {{cvt|232|CID|L|1}} engine was produced from 1964 until 1979. The 232 was the base six-cylinder engine on many models through 1979, and even towards the end of its usage, it was considered reasonably modern in design.<ref>{{cite book |title=Chilton's Auto Repair Manual 1982 |year=1987 |publisher=Chilton |isbn=978-0-8019-7052-8}}</ref>

After its midyear 1964 introduction in the "Typhoon" two-door hardtop as part of the mid-sized [[Rambler Classic]] line, the 232 engine was adapted to fit into the smaller 1965 [[Rambler American]] by using a special short water pump, an adaptive piece also used in the 1971 through 1975 Jeep CJ-5.<ref name="amcyclopedianode16">{{cite web |url= http://www.amcyclopedia.org/node/16 |title=1964 — 1965 American |author=((mhaas)) |date=17 January 2006 |website=amcyclopedia.org |archive-url= https://web.archive.org/web/20140302073556/http://www.amcyclopedia.org/node/16 |archive-date=2 March 2014 |access-date=17 April 2024}}</ref> 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.<ref name="amcyclopedianode16"/>

Through the 1970 model year, the 232 shared a deck height with the {{cvt|199|CID|L|1}} engines. Starting in 1971, AMC raised the deck height to produce the 258, and the 232 adopted the 199's longer connecting rods and shared deck height with the 258. Bore and stroke remained the same.

In 1972, the bell housing bolt pattern changed to match the larger version used on the V8 engines.<ref name="amcyclopedianode16"/>

Changes for the 1976 model year included [[Fuel economy in automobiles|fuel economy]] improvements that reduced emissions and warmup time.<ref name="ps75-10">{{cite magazine|last=Dunne |first=Jim |title=How American Motors does it |magazine=Popular Science |date=October 1975 |volume=207 |issue=4 |url= https://books.google.com/books?id=LQEAAAAAMBAJ&q=AMC+232+six&pg=PA117 |page=117 |via=Google Books |access-date=17 April 2024}}</ref> This was accomplished by reshaped [[carburetor]] air passages that pushed the [[fuel efficiency]] of a 232-equipped [[AMC Gremlin]] to {{cvt|30|mpgus|L/100 km mpgimp}} as tested by the [[United States Environmental Protection Agency]], compared to {{cvt|24|mpgus|L/100 km mpgimp}} in 1975.<ref name="ps75-10"/>

{{Hidden begin
|title = Applications:
|titlestyle = background:#88FF88; text-align:left;
|bodystyle = text-align:left;
}}
*[[Rambler Classic]] (1964–1966)
*[[Rambler American|Rambler American/AMC Rambler]] (1964–1969)
*[[AMC Marlin|Rambler/AMC Marlin]] (1965–1967)
*[[AMC Ambassador|Rambler/AMC Ambassador]] (1965–1970)
*[[AMC Rebel|Rambler/AMC Rebel]] (1967–1970)
*[[AMC Javelin]] (1968–1974)
*[[AMC Hornet]] (1970–1977)
*[[AMC Gremlin]] (1970–1978)
*[[AMC Matador]] (1971–1974)
*[[AMC Pacer]] (1975–1979)
*[[AMC Concord]] (1978–1979)
*[[AMC Spirit]] (1979)
*[[Jeep CJ]] (1972–1979)
*[[Jeep Cherokee (SJ)|Jeep Cherokee]] (1974–1979)
*[[Jeep Wagoneer]] (1965–1971)
*[[Jeep J-Series]] (1965–1970)
*[[Jeep Commando]] (1972–1973) (1976 in Spain)<ref>{{cite magazine |last=Lamm |first=Michael |title=Old cars never die ... they show up in foreign lands |magazine=Popular Mechanics |date=November 1976 |volume=146 |issue=5 |url= https://books.google.com/books?id=ouIDAAAAMBAJ&q=Jeep+232+engine&pg=PA160 |page=160 |via=Google Books |access-date=17 April 2024}}</ref>
*[[International Scout]] (1969–1971)
*[[International Light Line pickup]]s/[[International Travelall|Travelall]] (1968–1971)
*VAM Rambler American Hardtop (1965) U.S. equivalent AMC Rambler American 440H hardtop
*VAM Rambler American Rally (1969–1971) U.S. equivalent 1969 AMC Rambler Rogue sedan instead of hardtop and 1970–1971 Hornet X
*VAM Rambler American (1968–1972) U.S. equivalent AMC Rambler American sedans and AMC Hornet sedans 
*VAM Camioneta Rambler American (1968–1972) U.S. equivalent AMC Rambler American wagon and AMC Hornet Sportabout
*VAM Rambler Classic 660 (1965) U.S. equivalent AMC Rambler Classic
*VAM Rambler Classic 770 (1966–1969) U.S. equivalent 1966 AMC Rambler Classic sedans plus AMC Rebel four door sedan
*VAM Rambler Classic SST (1967–1969) U.S. equivalent AMC Rebel hardtop
*VAM Javelin (1968–1969) U.S. equivalent AMC Javelin
*VAM Gremlin (1974–1976) U.S. equivalent AMC Gremlin
{{Hidden end}}

[[File:VAM 252.jpg|thumb|right|A VAM 252 engine in a Mexican Javelin]]

===252===
The {{cvt|252|CID|L|1}} engine was produced by AMC's Mexican subsidiary [[Vehículos Automotores Mexicanos]] (VAM) beginning in 1969 and was dropped after 1972, replaced with AMC's 258 for the 1973 model year onward. This was similar to a 232 in stroke with a larger {{cvt|3.91|in|mm|1}} bore, for an actual displacement of {{cvt|252.15|CID|L|1}}. It was produced in VAM's Lerma, Estado de México engine plant.

'''Output for 1972 Rambler American Rally model ([[Horsepower#SAE gross power|gross]]):'''
*Horsepower {{cvt|170|hp|kW PS|0}} at 4600&nbsp;rpm
*Torque {{cvt|240|lbft|Nm|0}} at 2300&nbsp;rpm

'''Engine dimensions:'''
*[[Compression ratio]] 9.5:1
*Intake valve diameter {{cvt|2.02|in|mm}}
*Exhaust valve diameter {{cvt|1.6755|in|mm}}
*Connecting Rod length {{cvt|5.875|in|mm}}
*Deck height {{cvt|9.424|in|mm}}
*Bore {{cvt|3.91|in|mm|1}}
*Stroke {{cvt|3+1/2|in|mm|1}}

{{Hidden begin
|title = Applications:
|titlestyle = background:#88FF88; text-align:left;
|bodystyle = text-align:left;
}}
*VAM Javelin (1969–1970) U.S. equivalent — [[AMC Javelin]]
*VAM Rambler Classic SST (1969–1971) U.S. equivalent — [[AMC Rebel]] hardtop and [[AMC Matador]] hardtop
*VAM Rambler Classic 770 (1970) U.S. equivalent — [[AMC Rebel]] sedan
*VAM Rambler Classic DPL (1971) U.S. equivalent — [[AMC Matador]] sedan
*VAM Rambler American Rally (1972) U.S. equivalent — [[AMC Hornet]] Rallye X
{{Hidden end}}

===258===
[[File:1974 AMC Gremlin X red with white stripes AMO 2015 meet 8of8.jpg|thumb|258 engine in a 1974 [[AMC Gremlin]]]]
[[File:1980 AMC AMX engine bay 258 I6 CZ.jpg|thumb|Engine bay of a 1980 [[AMC Spirit]] AMX with 258 and emissions controls]]

The {{cvt|258|CID|L|1}} was produced from 1971 through 1990. It featured an [[undersquare]] {{cvt|3.75|in|mm|1}} bore and {{cvt|3.895|in|mm}} stroke; it was otherwise similar to the 199 and 232 (Note: Starting in the mid-1970s the 258's bore and stroke was changed to a {{cvt|3.82|in|mm}} bore over a 3.75" stroke. This allowed one block to be used for both the 232 and 258 and the same crankshaft blank could be milled to the two different strokes).

This engine is considered reliable, inexpensive, and torquey.<ref name="offroaders">{{cite web |url= http://www.offroaders.com/tech/jeep/engine-factory-amc258i6.htm |title=AMC 258 I6 |website=offroaders.com |access-date=17 April 2024}}</ref> Later 258 models (starting with the 1980 model year for [[California]] AMC Concords and Spirits, 1981 for California Jeeps, California [[AMC Eagle|Eagles]], and 49-state Concord and Spirits, as well as in 1982 for 49-state Eagles and all other applications) are equipped with [[AMC Computerized Engine Control]] (CEC) system. 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 {{convert|20|lb|kg|1}}.

This engine also found use in farm/industrial applications such as the International Harvester 4000 [[swather]].

{{Hidden begin
|title = Applications:
|titlestyle = background:#88FF88; text-align:left;
|bodystyle = text-align:left;
}}
*[[AMC Hornet]]/[[AMC Concord|Concord]]/[[AMC Eagle|Eagle]] (1971–1988)
*[[AMC Pacer]] (1975–1980)
*[[AMC Matador]] (1971–1978)
*[[AMC Gremlin]] and [[AMC Spirit|Spirit]] (1971–1983)
*[[International Scout]] and [[International Light Line pickup|Light Line trucks]] (1972–1980)
*[[Jeep CJ]] (1972–1986)
*[[Jeep Cherokee (SJ)|Jeep Cherokee]] and [[Jeep Wagoneer|Wagoneer]] (1972–1986)
*[[Jeep J-Series]] (1971–1988)
*[[Jeep Wrangler]] (1987–1990)
*[[Jeep Commando]] (1972–1973)
*VAM Rambler American (1973–1974) U.S. equivalent — AMC Hornet sedans
*VAM Rambler American Rally (1973–1974) U.S. equivalent — AMC Hornet X sedan instead of a hatchback
*VAM Camioneta Rambler American (1973–1974) U.S. equivalent — AMC Hornet Sportabout
*VAM American (1975–1983) U.S. equivalent — AMC Hornet sedan base model and AMC Concord sedan base model
*VAM American Rally (1975) U.S. equivalent — AMC Hornet X sedan instead of a hatchback
*VAM Camioneta American (1975–1983) U.S. equivalent — AMC Hornet Sportabout and Concord base model wagon
*VAM American ECD (1975–1979) U.S. equivalent — AMC Hornet DL two and four-door sedans and AMC Concord DL/Limited four-door sedan
*VAM Gremlin X (1976–1982) U.S. equivalent — AMC Gremlin X and AMC Spirit sedan X model equivalent
*VAM Gremlin (1977–1983) U.S. equivalent — AMC Gremlin and AMC Spirit sedan base model
{{Hidden end}}

===282===
[[File:1982 VAM Lerma 620 two-door liftback with 4.6 L at 2021 All AMC Day Cecil Dragway 31of32.jpg|thumb|VAM 4.6&nbsp;L engine]]

The {{cvt|282|CID|L|1}} engine was produced by AMC's Mexican subsidiary [[Vehículos Automotores Mexicanos]] (VAM) beginning in 1971 through 1986. This was similar to a 258 in stroke, cast with a larger {{cvt|3.917|in|mm}} bore, {{cvt|0.16|in|mm}} larger than the 258, making {{cvt|281.7|CID|L|1}}.<ref>{{cite web |url= http://membres.multimania.fr/pacer/mexeng.htm |title=Mexican AMC 6 Cyl. Engine Info |first=Thomas |last=Anhalt |archive-url= https://web.archive.org/web/20130529041905/http://membres.multimania.fr/pacer/mexeng.htm |archive-date=29 May 2013 |access-date=17 April 2024}}</ref> All VAM 282s from 1971 through 1978 were still advertised with an output measured using the gross rating system that was last used under AMC in 1971. The 1979 through 1983 engines were measured under the new net rating system. All units were produced in VAM's engine plant located in Lerma, Estado de México.

The 282, which had a larger bore, is considered the ancestor of the &nbsp;L stroker engine, where it is common for the engine rebuilder to use an AMC 258 crankshaft in a Jeep 4.0 cylinder block – a 4.5 uses the stock AMC 258 connecting rods (with stock or .020 overbore using aftermarket pistons). In contrast, the 4.6, 4.7, and 5.0 strokers use the 258 cranks, but retain the 4.0 connecting rods.

'''Output for 1971–1973 models (gross):'''
* Horsepower {{cvt|200|hp|kW PS|0}} at 4400&nbsp;rpm
* Torque {{cvt|280|lbft|Nm|0}} at 2200&nbsp;rpm
* Compression ratio 9.5:1

'''Output for 1974 models (gross):'''
* Horsepower {{cvt|200|hp|kW PS|0}} at 4400&nbsp;rpm
* Torque {{cvt|280|lbft|Nm|0}} at 2200&nbsp;rpm
* Compression ratio 8.5:1

'''Output for 1975–1976 models (gross):'''
* Horsepower {{cvt|200|hp|kW PS|0}} at 4400&nbsp;rpm
* Torque {{cvt|280|lbft|Nm|0}} at 2200&nbsp;rpm
* Compression ratio 7.7:1

'''Output for 1977–1978 models (gross):'''
* Horsepower {{cvt|200|hp|kW PS|0}} at 4400&nbsp;rpm
* Torque {{cvt|280|lbft|Nm|0}} at 2200&nbsp;rpm
* Compression ratio 8.0:1

'''Output for 1979–1981 Standard models (net):'''
* Horsepower {{cvt|132|hp|kW PS|0}} at 3800&nbsp;rpm
* Torque {{cvt|216|lbft|Nm|0}} at 2200&nbsp;rpm
* Compression ratio 8.0:1

'''Output for 1979 American 06/S and 1980–81 Rally GT models (net):'''
* Horsepower {{cvt|172|hp|kW PS|0}} at 4200&nbsp;rpm
* Torque {{cvt|225|lbft|Nm|0}} at 2600&nbsp;rpm
* Compression ratio 8.5:1

'''Output for 1982–1983 models (net):'''
* Horsepower {{cvt|129|hp|kW PS|0}} at 4000&nbsp;rpm
* Torque {{cvt|218|lbft|Nm|0}} at 1800&nbsp;rpm
* Compression ratio 8.5:1

'''Engine dimensions:'''
* Intake valve diameter {{cvt|2.02|in|mm}}
* Exhaust valve diameter {{cvt|1.6755|in|mm}}
* Connecting rod length {{cvt|5.875|in|mm}}
* Deck height {{cvt|9.424|in|mm}}
* Bore {{cvt|3.917|in|mm}}
* Stroke {{cvt|3.895|in|mm}}

{{Hidden begin
|title = Applications:
|titlestyle = background:#88FF88; text-align:left;
|bodystyle = text-align:left;
}}
*VAM Javelin (1971–1973) U.S. equivalent — [[AMC Javelin]]
*VAM Classic DPL (1972–1976) U.S. equivalent — [[AMC Matador]] Sedan
*VAM Classic Brougham (1972, 1974–1976) U.S. equivalent — 1972 [[AMC Matador]] hardtop and [[AMC Matador]] Brougham coupe
*VAM Classic AMX (1974–1976) U.S. equivalent — [[AMC Matador]] X coupe
*VAM Pacer (1976–1979) U.S. equivalent — [[AMC Pacer]] coupe
*VAM Pacer X (1979) U.S. equivalent — [[AMC Pacer]] X coupe
*VAM American Rally (1976–1977) U.S. equivalent — [[AMC Hornet]] X sedan instead of hatchback
*VAM American Rally AMX (1978–1979) U.S. equivalent — [[AMC Concord]] AMX hatchback
*VAM American GFS (1977–1982) U.S. equivalent — [[AMC Hornet]] DL two-door sedan plus [[AMC Concord]] DL and Limited two-door sedans
*VAM Camioneta American Automática (1977–1978) U.S. equivalent — [[AMC Hornet]] DL wagon and [[AMC Concord]] DL wagon, both with automatic transmission
*VAM Camioneta American DL (1979–1983) U.S. equivalent — [[AMC Concord]] DL and Limited wagons
*VAM American 06/S (1979) U.S. equivalent [[AMC Concord]] two-door sedan, high-performance limited edition
*VAM American ECD (1980–1982) U.S. equivalent — [[AMC Concord]] DL and Limited four-door sedans
*VAM Rally AMX (1980–1983) U.S. equivalent — [[AMC Spirit]] GT coupe, standard version
*VAM Rally GT (1980–1981) U.S. equivalent — [[AMC Spirit]] GT coupe, high-performance version
*VAM Rally SST (1981) U.S. equivalent — [[AMC Spirit]] Limited coupe
*[[VAM Lerma]] (1981–1982)
*VAM Jeep Wagoneer (1972–1983) U.S. equivalent — AMC Jeep Wagoneer
*Renault/VAM Jeep Grand Wagoneer from 1984 through 1986 (U.S. equivalent — Jeep Grand Wagoneer)
{{Hidden end}}

==={{anchor|4.0|242}} 4.0===
[[File:1993 Jeep Grand Cherokee Laredo - Blackberry with Crimson interior 16.jpg|thumb|Engine bay of a 1993 [[Jeep Grand Cherokee]] with 4.0&nbsp;L]]
[[File:Jeep 5 millionth 4.0 engine r.jpg|thumb|The 5 millionth Jeep 4.0 engine produced on the "Greenlee Block Line" dated June 15, 2001]]

American Motors began developing the {{cvt|242|cuin|L|1}} engine in 1984 and it was completed in just 26 months using many off-the-shelf components while featuring, among others, additional strength, improved combustion chamber, port setup, and cam profile.<ref name="pm-tech-amc">{{cite magazine |url= https://books.google.com/books?id=z-MDAAAAMBAJ&q=1987+American+Motors+was+caught+performance+stronger+4.0&pg=PA143 |page=145 |title=Technical Highlights: American Motors |first=Pete |last=Warren |magazine=Popular Mechanics |date=October 1986 |volume=163 |issue=10 |via=Google Books |access-date=17 April 2024}}</ref> The total weight of the new engine was {{convert|483|lb|kg}}, only one pound more than the 258 six despite its heavier-duty components and parts.<ref name="pm-tech-amc"/> The cast aluminum valve cover featured 15 bolts, the industry's most, to achieve a positive seal.<ref name="pm-tech-amc"/>

The new engine, which was introduced in 1986 for the 1987 model year, was a further evolution of AMC's 258 six.<ref name=kickass>{{cite magazine |url= http://www.jpmagazine.com/techarticles/engine/154_0604_jeeps_kick_ass_engine_history_4_liter/index.html |last=Tellem |first=Tori |title=Jeeps Kick Ass Engine — The History Of The 4.0 L (page 1) |magazine=JP Magazine |date=April 2006 |archive-url= https://web.archive.org/web/20081224045801/http://www.jpmagazine.com/techarticles/engine/154_0604_jeeps_kick_ass_engine_history_4_liter/index.html |archive-date=24 December 2008 |access-date=17 April 2024}}</ref><ref>{{cite magazine |url= http://www.jpmagazine.com/techarticles/engine/154_0604_jeeps_kick_ass_engine_history_4_liter/the_90s.html |last=Tellem |first=Tori |title=Jeeps Kick Ass Engine — The History Of The 4.0 L (page 2 |magazine=JP Magazine |date=April 2006 |archive-url= https://web.archive.org/web/20081029043449/http://www.jpmagazine.com/techarticles/engine/154_0604_jeeps_kick_ass_engine_history_4_liter/the_90s.html |archive-date=29 October 2008 |access-date=17 April 2024}}</ref> It had a {{cvt|3.875|in|mm}} bore and a {{cvt|3.414|in|mm}} stroke giving it a displacement of {{cvt|241.6|cuin|L|1}}.<ref name=xjmanual>{{cite book |title=Service Manual 2000 Jeep Cherokee |chapter=XJ 4.0 L|page=115 |publisher=DaimlerChrysler |year=2000 |quote=bore x stroke = 3.875 x 3.414 inches}}</ref> Connecting rod length was 6.125 inches — similar to the discontinued 199 which was phased out in 1970.

The 4.0&nbsp;L is one of AMC's best-known engines.<ref>{{cite book |first=Jim |last=Allen |title=Jeep: Collector's Library |page=178 |publisher=MBI Publishing |year=2003 |isbn=978-0-7603-1486-9}}</ref> It was one of four AMC engines kept in production when Chrysler bought AMC in 1987. Chrysler engineers continued to refine the engine to reduce [[noise, vibration, and harshness]]. The last in the line of the AMC inline sixes, the 4.0&nbsp;L is regarded as one of the best Chrysler 4x4 off-road engines.<ref>{{cite web |url= https://www.motortrend.com/how-to/129-0901-jeep-motors-history/ |last=Worthy |first=Willie |title=Jeep Motors History — Willies Workbench: Jeep Engines De-Mystified |work=Motor Trend |date=January 2009 |access-date=17 April 2024}}</ref> 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."<ref>{{cite magazine |url= http://www.motortrend.com/roadtests/suvs/112_9903_1997_jeep_cherokee/viewall.html |magazine=Motor Trend |date=March 1999 |first1=Jeff |last1=Bartlett |first2=Randy |last2=Lorentzen |title=Road Test: '97 Jeep Cherokee — Long-Term Wrap-Up |access-date=17 April 2024 |archive-date=23 August 2011 |archive-url= https://web.archive.org/web/20110823115702/http://www.motortrend.com/roadtests/suvs/112_9903_1997_jeep_cherokee/viewall.html |url-status=dead}}</ref> The engine is known for longevity, and can sometimes go more than {{convert|300000|mi|km|0}} without rebuilding.<ref>{{cite web |url= https://www.cherokeeforum.com/f2/cherokee-longevity-17463/ |title=Cherokee longevity |website=cherokeeforum.com |access-date=17 April 2024}}</ref><ref>{{cite web|url= https://www.vehiclehistory.com/articles/the-jeep-4-0l-engine-a-legend-to-many |title=The Jeep 4.0L Engine: A Legend To Many |author=((Sandy B)) |date=9 February 2021 |website=vehiclehistory.com |access-date=17 April 2024}}</ref> 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. Described "as reliable as a block of wood" by ''[[Popular Mechanics]]'' and ranked first among "the ten best car engines they stopped making in the past 20 years," the 4.0&nbsp;L should run 200,000 miles before a rebuild is even expected and it is also able to "suffer running conditions that'd kill most motors."<ref>{{cite web |last=Jancer |first=Matthew |title=The 10 Best Car Engines They Stopped Making in the Last 20 Years |url= https://www.popularmechanics.com/cars/car-technology/g25336816/car-engines-they-stopped-making/ |work=Popular Mechanics |date=29 November 2018 |access-date=17 April 2024}}</ref> It is rated by SlashGear's "most reliable inline six-cylinder engines ever".<ref>{{cite web|url=  https://www.slashgear.com/1489902/what-made-jeep-4-0l-engine-so-great/ |title=A Look At What Made Jeep's 4.0L Engine So Great |first=Joe |last=Capraro |date=14 January 2024 |work=SlashGear |access-date=2 April 2025}}</ref> The 4.0 "has a very good reputation for dependability and durability. It's generally considered indestructible."<ref>{{cite book|url= https://www.google.com/books/edition/Jeep_4_0_Engines/q-JZBAAAQBAJ?hl=en&gbpv=1&dq=development+of+the+jeep+4.0+engine&printsec=frontcover |page=5 |title=Jeep 4.0 Engines - How to Rebuild and Modify |first=Larry |last=Shepard |date=2014 |publisher=CarTech |isbn=9781613251386 |access-date=2 April 2025 |via=Google Books}}</ref>

When introduced, the block-mounted oil filter check valve was eliminated on the 4.0 (along with the 2.5 and 4.2&nbsp;L engines manufactured after September 1986) when AMC engineers standardized their oil filters. The pre-1987 engines had an oil filter adapter with 3/4 (cylinder block end) and 13/16 threads (which used a GM oil filter common to Buick, Oldsmobile, Pontiac, and Cadillac V8 engines). In contrast, the 1987 through 2006 engines were initially fitted with a {{cvt|20|mm|in}} metric thread filter (later revised in 1991 for the common 3/4 threaded Mopar and Ford V8 oil filter; the oil filter adapter was redesigned where the oil filter is positioned 90 degrees offset adjacent to the starter motor — a Ford V8 oil filter can be used in place of the short filter increasing oiling capacity).

The first 4.0&nbsp;L engines in 1987 had a [[Renix]] ([[Renault]]/[[Bendix Corporation|Bendix]]) [[engine management system]] considered quite advanced for their time.<ref name="offroaders"/> A [[engine knock|knock]] sensor allowed the [[Engine control unit|ECU]] to control spark advance in response to fuel octane and engine load. Unfortunately, few scan tools can interface with the system to pull diagnostics codes. RENIX systems also have no permanent memory for diagnostics codes, thus making diagnosing intermittent problems more difficult.<ref name="stern">{{cite web |url= https://www.allpar.com/threads/jeep%E2%80%99s-4-0-liter-powertech-straight-six-engine.229895/#post-1085223993 |last=Stern |first=Peter |first2=Frank |last2=Swygert |title=The Jeep 4.0 liter PowerTech Straight-Six Engine |website=allpar.com |date=16 November 2020 |access-date=17 April 2024}}</ref>

The 1987 Renix 4.0&nbsp;L was rated at {{cvt|173|hp|kW PS|0}} and {{cvt|220|lbft|Nm|0}}. In 1988, the 4.0 received higher flowing fuel injectors, raising output to {{cvt|177|hp|kW PS|0}} and {{cvt|224|lbft|Nm|0}} — more power than some configurations of the [[Ford small block engine|Ford 302]], [[Chevrolet small-block engine (first- and second-generation)|Chevrolet 305]], and [[Chrysler LA engine|Chrysler 318]] [[V8 engine]]s, and more than any of the Japanese 6-cylinder truck engines, but with comparable or superior fuel economy.<ref name="stern"/>

In 1991, a Chrysler [[multi-port fuel injection]] system replaced the RENIX system, and the intake ports were raised approximately {{cvt|1/8|in|mm}} for a better entry radius. 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. The camshaft timing was also changed. The net result was an engine that made {{cvt|190|hp|kW PS|0}} and {{cvt|225|lbft|Nm|0}}. [[Badge|Badging]] on most Jeeps equipped with this engine reads "4.0 Litre HIGH OUTPUT." The new cam profile combined with altered computer programming eliminated the need for an EGR valve and knock sensor, but made the engine more sensitive to alterations, especially where emissions are concerned.{{Citation needed|date=April 2011}} The OEM fuel injectors used with the [[Mopar]] MPI system (manufactured by [[Siemens]]) have been known to leak fuel especially with [[OBD-II PIDs|OBD-II]] where plugged [[catalytic converter]]s are common which usually throws a P0420 code.

Minor changes were made to the cylinder head for the 1995 model year. In 1996, the engine block was redesigned for greater strength. The new block had more webbing and a stud girdle for added rigidity of the crankshaft main bearings. Engines installed in 1999 Grand Cherokees carried the "[[Chrysler PowerTech engine (disambiguation)|PowerTech]]" name that had been used intermittently in prior years and on other Chrysler truck and SUV engines. The name was subsequently passed on to 4.0s in the other Jeep models that used the engine, the Cherokee and Wrangler. The cylinder head was again changed for the 2000 model year to a more emissions-friendly design.{{Citation needed|date=April 2011}} This head was designated as "0331" in the casting number. Early 0331 heads are prone to cracking, causing coolant to contaminate the oil, which can lead to catastrophic engine failure. The head cracks in the center between #3 and #4 cylinders. The crack is usually discernible with the valve cover removed as a "milky" tan line. This condition is usually discovered before a catastrophic engine failure, but can lead there if not corrected promptly. The casting was fixed in mid to late 2001, but the same casting number was retained. The "fixed" heads have "TUPY" cast in the center where the cracks used to occur.<ref>{{cite web |url= https://www.cherokeeforum.com/f2/00-01-xj-cracked-cylinder-head-overview-118922/ |title='00–'01 XJ Cracked Cylinder Head (OVERVIEW) |website=cherokeeforum.com |access-date=17 April 2024}}</ref> Also new for the 2000 model year, was the distributor-less, coil on plug ignition system.<ref>{{cite web |url= https://4wdmechanix.com/pdf-downloads/Jeep%20Ignition%20Upgrades%20for%20Pre-EFI.pdf |title=Pre-EFI Jeep Inline Six-Cylinder Ignition Upgrades (Issue #3, April 2010) |first=Moses |last=Ludel |website=4wdmechanix.com |access-date=17 April 2024}}</ref> Option code: '''ERH'''.

Output:<ref>{{cite web |url= http://www.edmunds.com/jeep/?ps=used |title=Used Jeep Models |work=Edmunds|access-date=17 August 2012}}</ref>
:* 1987–1990: {{cvt|177|hp|kW PS|0}} at 4500&nbsp;rpm and {{cvt|224|lbft|Nm|0}} at 2500&nbsp;rpm
:* 1991–1995: {{cvt|190|hp|kW PS|0}} at 4750&nbsp;rpm and {{cvt|225|lbft|Nm|0}} at 4000&nbsp;rpm
:* 1996–2001: {{cvt|190|hp|kW PS|0}} at 4600&nbsp;rpm and {{cvt|225|lbft|Nm|0}} at 3000&nbsp;rpm
:* 2001–2006: {{cvt|190|hp|kW PS|0}} at 4600&nbsp;rpm and {{cvt|235|lbft|Nm|0}} at 3200&nbsp;rpm

The 4.0&nbsp;L engine was discontinued at the end of the 2006 model year, replaced in the redesigned 2007 JK [[Jeep Wrangler]] by Chrysler's [[Chrysler 3.3 engine#3.8|3.8 L OHV V6]], which originated in the company's minivans.

{{Hidden begin
|title = Applications:
|titlestyle = background:#88FF88; text-align:left;
|bodystyle = text-align:left;
}}
*1987–2001 [[Jeep Cherokee (XJ)|Jeep Cherokee]]
*1993–2004 [[Jeep Grand Cherokee]]
*1987–1990 [[Jeep Wagoneer]]
*1987–1992 [[Jeep Comanche]]
*1991–2006 [[Jeep Wrangler]]
{{Hidden end}}

===Connecting rod lengths===
'''1964–1970:'''
*{{cvt|199|CID|L|1}} — {{cvt|6.125|in|mm}}
*{{cvt|232|CID|L|1}} — {{cvt|5.875|in|mm}}
*{{cvt|252|CID|L|1}} — {{cvt|5.875|in|mm}}

'''1971–2006:'''
*{{cvt|232|CID|L|1}} — {{cvt|6.125|in|mm}}
*{{cvt|242|CID|L|1}} — {{cvt|6.125|in|mm}}
*{{cvt|258|CID|L|1}} — {{cvt|5.875|in|mm}}
*{{cvt|282|CID|L|1}} — {{cvt|5.875|in|mm}}
*The [[Engine displacement|displacement]] differs between 1990–1995 and 1996–2006 versions of the 4.0&nbsp;L engines by around {{cvt|1.7|CID|L|2}}. Both had a bore of {{cvt|3.875|in|mm}}, but the stroke decreased slightly from {{cvt|3.4375|in|mm}} on the earlier engine to {{cvt|3.414|in|mm}} on 1996 and later engines. The small stroke change of {{cvt|0.03|in|mm}} was accomplished by moving the piston pin and changing the crankshaft stroke; the rod length did not change.

The deck height of the AMC six-cylinder block was increased by {{cvt|1/8|in|mm}} (half the rod length difference) in 1971 to allow for the longer stroke required for the 258. There are only two deck heights. Tall deck is {{cvt|9.528–9.534|in|mm}}. Short should be {{cvt|9.278–9.284|in|mm}}. Tall is from 1974 through 1976 AMC factory service manuals; before 1974, deck height was not printed. Deck height changed slightly over the years 1977–1982 service manuals state {{cvt|9.487–9.493|in|mm}}, the 1993 Jeep factory manual states {{cvt|9.429–9.435|in|mm}}. Deck heights may have changed to accommodate slightly different compression ratios over the years.<ref name="74 AMC Technical Service Manual">{{cite book |title=1974 ANC Technical Service Manual |year=1974 |publisher=American Motors Corporation |section=Group 1A, Six-Cylinder Engines |page=1A-31}}</ref>

The 1971 and older blocks use a "small" bell housing bolt pattern exclusive to AMC and small Nash sixes. In 1972, the bell housing bolt pattern was changed to match the AMC V8s. Its final use was in 2006 when the 4.0&nbsp;L was phased out. Four bolts on the cylinder block are matched to the transmission bell housing where an adapter plate serves as a dust cover — two additional bolt holes on the transmission bellhousing used on the AMC V8 are used to secure the dust cover. The 1971 model year 258 uses the "small" pattern, the only version of the 258 to do so.

==See also==
*[[AMC straight-4 engine]]
*[[AMC V8 engine]]
*[[List of AMC engines]]
*[[AMC and Jeep transmissions]]
*[[List of Chrysler engines]]

==References==
{{Reflist|colwidth=30em}}

*{{cite web|title=4.0 head and EFI on a 4.2 block |url= https://www.jeepstrokers.com/forum/viewtopic.php?f=6&t=24 |date=13 February 2008 |website=jeepstrokers.com |access-date=17 April 2024}}

==External links==
{{Commons category}}
* [http://www.amcrc.com/ AMC Rambler Club] encourages and promotes the preservation, restoration, and collection of automobiles produced by American Motors Corporation, as well as collecting information and printed matter relating to these cars
* [https://amo.club/ American Motors Owners Association] aiding and encouraging the use, enjoyment, preservation, and restoration of vehicles built by American Motors Corporation between 1954 and 1988 model years

{{American Motors}}

[[Category:AMC engines]]
[[Category:Chrysler engines]]
[[Category:Straight-six engines]]
[[Category:Jeep engines]]
[[Category:Products introduced in 1964]]