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The American Motors Corporation (AMC) straight-6 family of engines was used in AMC passenger cars and Jeep vehicles from 1964 through 2006. (詳細はoverhead valve (OHV) and flathead (L-head) side-valve versions. Sometimes referred to as the 196 engine, this engine was originally designed by Nash and introduced in the 1941 Nash Ambassador 600 model. It featured only four main bearings, unlike the 7-main-bearing 234 flathead engine it replaced. It was a flathead design displacing . It was later enlarged to , and finally to . It was 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 engine in 1961. It was produced through 1964. This engine used cast-iron cylinder liners and a cast-iron head. The cylinder heads for the two types of block (aluminum and cast iron) are of similar design, but are not interchangeable. The cylinder head for the aluminum block is roughly 1/8" wider than that for the cast iron block and uses a slightly different head bolt pattern.〔1950-1965 Nash/AMC Technical Service Manuals〕 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 and to re-torque them every . With modern head gaskets this service interval can be extended to re-torque the bolts every , 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 heavy design. The head expands and contracts by as much as 0.020" in height during normal operation, this loosens the bolts over time and eventually will cause the seal between head and block to fail. This maintenance is also imperative to prevent the engine from overheating (the first sign of a blown head gasket) and 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 allowed to overheat. Good replacement heads and aluminum blocks for these engines are now difficult to find. ==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 "Torque Command" inline six was AMC's first modern six-cylinder engine. To commemorate the engine's May 1964 introduction, 2,520 "Typhoon" cars were made on the Rambler Classic hardtop body. Each featured the 8.5:1 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. The new engine replaced the Nash 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 version finally replaced the aging 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." Both the 199 and 232 featured a bore, and either a or stroke. The 199 was discontinued in 1970; the 232 was offered alongside the (made by using a 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「AMC straight-6 engine」の詳細全文を読む スポンサード リンク
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