AMC Straight-6 Engine 1 AMC Straight-6 Engine
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AMC straight-6 engine 1 AMC straight-6 engine The American Motors Corporation (AMC) straight-6 family of engines was used in AMC passenger cars and Jeep vehicles from 1964 through 2006. 195.6 American Motors' first straight-six engine was the 195.6 cu in (unknown operator: u'strong' L). It was produced from 1958 through 1965 in both overhead valve (OHV) and flathead (L-head) side-valve versions. Sometimes referred to as the 196 engine, this engine was originally designed by Nash in the 1930s as a flathead, and redesigned as an OHV engine in 1956. The flathead version was discontinued for 1956–1957, but reemerged in 1958 as the economy engine for the "new" Rambler American. When the engine was changed to an OHV configuration the water pump was moved from the left side of the engine (driven by a shaft extending from the back of the generator) to the front above the timing chain. When the flathead model was reintroduced it also received the new water pump. Equipped with such high quality parts as forged crankshafts and connecting rods, these engines earned a reputation for remarkable durability. The flathead, however, was prone to the typical flathead problem of overheating under sustained heavy load. This was from the hot exhaust traveling through the cylinder block to the exhaust manifold. American Motors introduced a die-cast aluminum block version of the OHV 195.6 cu in (unknown operator: u'strong' L) engine in 1961. It was produced through 1964. This engine used cast-iron cylinder liners and a cast-iron head. The cast iron and aluminum block heads are of similar design but will not interchange. The aluminum block is slightly wider than the iron block and the bolts on the left and right sides of the cylinders are further apart. The 196 OHV requires more periodic maintenance than newer-model engines. The head bolts must be re-torqued (retightening process) regularly. Factory service manuals recommend that head bolt torque be checked every 4000 mi (unknown operator: u'strong' km) and to re-torque them every 8000 mi (unknown operator: u'strong' km). With modern head gaskets this service interval can be extended to re-torque the bolts every 12000 mi (unknown operator: u'strong' km), or every other year. The cause of the headbolts loosening over time is believed to be thermal expansion and contraction of the head due to the rather massive design. This loosens the bolts over time and eventually causes the seal between the head and block to fail. This maintenance is imperative to prevent the engine from running hot (the first sign of a blown head gasket) and thus warping or cracking the head. The cast-iron liners in the aluminum block version can also shift if the head bolts are not properly torqued and the engine is run hot. If this process is not followed, then repairs will be necessary and replacement heads and aluminum blocks for these engines are now more difficult to find.[1] The modern era I-6 The company designed an entirely new six-cylinder with a short stroke and seven main bearing crankshaft for 1964. This design was produced in various forms through 2006. The 232 cu in (unknown operator: u'strong' L) "Torque Command" inline six was AMC's first modern six-cylinder engine.[2] To commemorate the engine's May 1964 introduction, 2,520 "Typhoon" cars were made on the Rambler Classic hardtop body.[3] Each featured the 145 hp (unknown operator: u'strong' kW) 8.5:1 Engine bay of a 1968 Rambler American AMC straight-6 engine 2 compression ratio engine, Solar Yellow body paint, a Classic Black roof, and a distinctive "Typhoon" script in place of the usual "Classic" name. All other AMC options (except engine options) were available.[4] The new engine replaced the Nash 195.6 cu in (unknown operator: u'strong' L) OHV I6 in the Classic and Ambassador for the 1965 model year (this was also the first use of a six in the Ambassador since 1956). In 1966, a 199 cu in (unknown operator: u'strong' L) version finally replaced the aging 195.6 cu in (unknown operator: u'strong' L) OHV and L-head engines. Road tests by Consumer Reports described the new powerplant as "a very smooth and quiet engine, which should give good performance."[5] Both the 199 and 232 featured a 3.75 in (unknown operator: u'strong' mm) bore, and either a 3.0 in (unknown operator: u'strong' mm) or 3.5 in (unknown operator: u'strong' mm) stroke. The 199 was discontinued in 1970; the 232 was offered alongside the 258 cu in (unknown operator: u'strong' L) (made by using a 3.895 in (unknown operator: u'strong' mm) stroke crankshaft and slightly taller block) during the 1970s, but was discontinued in 1979. Increasingly stringent emission control regulations continued to decrease the engine's power output, making the smaller version inadequate as increasingly stringent safety regulations also made vehicles heavier. 199 The 199 cu in (unknown operator: u'strong' L) (198.8 cuin / 3,258 cc) 199 was produced from 1965 to 1970. Applications: • Rambler Classic (1965–66, fleet cars only) • Rambler American/AMC Rambler (1965–69) • AMC Hornet (1970) • AMC Gremlin (1970) • VAM Rambler American (1966–1969) U.S. equivalent - AMC Rambler American and AMC Rambler. 232 The 232 cu in (unknown operator: u'strong' L) (231.9 cu in / 3,801 cc) 232 was produced from 1964 to 1979. The 232 was the base six-cylinder engine on many models through 1979, and even towards the end of its usage was considered reasonably modern in design.[6] 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 1971–1975 Jeep CJ-5.[7] Air conditioning was available only with the Standard 232 in a 1966 Rambler Classic older 196 engine in the American, because there wasn't space for it with the longer 232.[7] Through the 1970 model year, the 232 shared a deck height with the 199 cu in (unknown operator: u'strong' L) 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.[7] AMC straight-6 engine 3 Changes for the 1976 model year included fuel economy improvements that also reduced emissions and reduced warmup time.[8] This was accomplished by reshaped carburetor air passages that pushed the fuel efficiency of a 232-equipped AMC Gremlin to 30 mpg (unknown operator: u'strong' L/100 km; unknown -US operator: u'strong' mpg ) as tested by the United States -imp Environmental Protection Agency, compared to 24 mpg (unknown -US operator: u'strong' L/100 km; unknown operator: u'strong' mpg ) in 1975.[8] -imp Engine bay of a 1975 AMC Hornet with a 232 Applications: • Rambler Classic (1964–1966) • Rambler American/AMC Rambler (1964–1969) • Rambler/AMC Marlin (1965–1967) • Rambler/AMC Ambassador (1965–1970) • Rambler/AMC Rebel (1967–70) • AMC Javelin (1968–74) • AMC Hornet (1970–77) • AMC Gremlin (1970–78) • AMC Matador (1971–74) • AMC Pacer (1975–79) • AMC Concord (1978–79) • AMC Spirit (1979) • Jeep CJ (1972–79) • Jeep Cherokee (1974–79) • Jeep Wagoneer (1965–1971) • Jeep J series trucks (1965–1970) • Jeep Commando (1972–1973) (1976 in Spain)[9] • International Harvester Scout (1969–1971) • International Harvester Light Line pickups/Travelall 252 The 252 cu in (unknown operator: u'strong' L) engine was produced by AMC's Mexican subsidiary Vehiculos 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 3.91 in (unknown operator: u'strong' mm) bore, for an actual displacement of 252.15 cu in (unknown operator: u'strong' cc). Output for 1972 Rambler American Rally model (gross): • Horsepower 170 hp (unknown operator: u'strong' kW) @ 4600 rpm • Torque 240 lb·ft (unknown operator: u'strong' N·m) @ 2300 rpm Engine dimensions: • Compression ratio 9.5:1 • Intake valve diameter 2.020 in (unknown operator: u'strong' mm) • Exhaust valve diameter 1.6755 in (unknown operator: u'strong' mm) • Pushrod length 5.875 in (unknown operator: u'strong' mm) AMC straight-6 engine 4 • Deck height 9.424 in (unknown operator: u'strong' mm) • Bore 3.910 in (unknown operator: u'strong' mm) • Stroke 3.50 in (unknown operator: u'strong' mm) Applications: • VAM 1969 and 1970 Javelin (U.S. equivalent - AMC Javelin) • VAM 1969 through 1971 Rambler Classic SST (U.S. equivalent - AMC Rebel hardtop and AMC Matador hardtop) • VAM 1970 Rambler Classic 770 (U.S. equivalent - AMC Rebel sedan) • VAM 1971 Rambler Classic DPL (U.S. equivalent - AMC Matador sedan) • VAM 1972 Rambler American Rally (U.S. equivalent - AMC Hornet Rallye X) 258 The 258 cu in (unknown operator: u'strong' L) was produced from 1971 to 1990. It featured an undersquare 3.75 in (unknown operator: u'strong' mm) bore and 3.895 in (unknown operator: u'strong' mm) stroke; it was otherwise similar to the 199 and 232. This engine is considered reliable, inexpensive, and torquey."[10] Later 258 models (starting with the 1980 model year for California AMC Concords and Spirits, 1981 for California Jeeps, California 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.