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Nash Rambler straight-six engine

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Main article: List of AMC engines

Nash Rambler straight-six engine
The 196ci OHV engine in a 1964 Rambler American
Overview
ManufacturerAmerican Motors Corporation
Production1940–1965
Layout
ConfigurationNaturally aspirated Straight-6
Displacement
  • 172.6 cu in (2.8 L)
  • 184.1 cu in (3.0 L)
  • 195.6 cu in (3.2 L)
Cylinder bore3+1⁄8 in (79.38 mm)
Piston stroke
  • 3+3⁄4 in (95.25 mm)
  • 4 in (101.60 mm)
  • 4+1⁄4 in (107.95 mm)
Cylinder block materialCast-iron/Aluminum
Cylinder head materialCast-iron
Valvetrain
Combustion
Fuel systemCarburetor
Fuel typeGasoline
Cooling systemWater-cooled

The Nash Rambler engine is a family of straight-six engines that were produced by Nash Motors and then American Motors Corporation (AMC), and used in Nash, Rambler, and AMC passenger cars from 1940 through 1965. It was succeeded by the AMC straight-6 engine in 1964, a completely new design. The engine evolved in several displacements and was built with two different valvetrains. The engine was originally of a flathead layout; an OHV version was introduced in 1956 although the flathead continued to be available. A version of the OHV engine with an aluminum block was introduced in 1961.

173 (Nash 600)

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"173" L-head engine in a 1949 Nash 600

Introduced in the autumn of 1940 for the 1941 Nash 600, it was originally designed to be an economy engine by Nash Motors, who initially called it the "Flying Scot" engine.[1] Nash went on to merge with Hudson to form AMC in 1954.[2][3][4] The initial design had a 3+1⁄8 inches (79.4 mm) bore and a 3+3⁄4 in (95.3 mm) stroke, for a displacement of 172.6 cu in (2.8 L; 2,828 cc). This bore was to be kept for all the variants of the engine, which were enlarged by increasing the stroke – an unusual practice given that changing forging is more expensive than changing the block casting.[5] The intake and exhaust manifolds were integrated into the cylinder block casting to reduce both weight and cost; Nash drew attention to the increased reliability of the design by marketing it as "Monitor Sealed".[2] To help keep costs down, the 600 engine had four main bearings, unlike the 7-main-bearing 234 flathead engine it replaced. The new, smaller flathead design was initially rated at 75 hp (56 kW) at 3,600 rpm.[1][2] The engine combined with the new Ambassador's advanced "unitized" construction design provided better than 25 mpg‑US (9.4 L/100 km; 30 mpg‑imp).[6]

When the war ended, Nash updated the 600 for 1946, increasing power to 80 hp (60 kW) at 3,800 rpm.[7] Updates included larger intake valves, reworked manifold and valve passages, and a revised head which provided a somewhat higher compression ratio. A triple-venturi, down-draft carburettor replaced the earlier type, and a number of minor changes to increase durability were also made.[7] The 173 continued to be used for the Nash Rambler until 1952.

184

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Upping the stroke to 4 in (101.6 mm) bore in 1950 increased the displacement to 184.1 cu in (3.0 L; 3,016 cc) for the Nash Statesman. This L-head engine was also installed on the Nash Rambler until the end of the 1955 model year.

196

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The 195.6 cu in (3.2 L; 3,205 cc) model was produced from 1952 through 1965, initially as a flathead (L-head) side-valve, and later in an overhead valve (OHV) version. It became the new American Motors Corporation's first straight-six engine.

This engine was redesigned as an OHV for the 1956 model year.[5] The flathead version was discontinued between 1956 and 1957, but reemerged in 1958 as the economy engine for the "new" Rambler American and was available through 1965.[5] The new OHV configuration for 1956 continued with the water pump mounted on the left side of the engine (driven by a shaft extending from the back of the generator).[5] This was changed for 1957 with the water pump mounted on the front of the engine above the timing chain.[5] When the flathead model was reintroduced, it received the new front mounted water pump. Featuring high-quality parts such as forged crankshafts and connecting rods, these engines earned a reputation for durability. However, the flathead was prone to the typical problem of overheating under sustained heavy loads. The excessive heating was caused by the hot exhaust going through the cylinder block to the exhaust manifold.

American Motors introduced a die-cast aluminum block version of the OHV 195.6 cu in (3.2 L) engine in 1961. It was produced through 1964.[8] 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) have similar designs 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.[9]

The 196 OHV requires more periodic maintenance than newer-model engines. The head bolts must be re-torqued (retightening process) regularly.[10] Factory service manuals recommend that head bolt torque be checked every 4,000 mi (6,400 km) and to re-torque them every 8,000 mi (13,000 km). Modern head gaskets can extend this service interval to re-torque the bolts every 12,000 mi (19,000 km), or every other year. The cause of the head bolts 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 0.02 in (0.51 mm) in height during normal operation; this loosens the bolts over time and eventually will cause the seal between the head and block to fail.[11] 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.[12]

See also

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References

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  1. ^ a b Nash Offers 15 New Models in Three Series For 1942 (PDF) (Press Kit), Detroit, MI: Nash Motors Press Bureau, 8 September 1941, pp. 4, 7
  2. ^ a b c McGuire, Bill (16 December 2021). "Trendsetter: The 1941 Nash 600". macsmotorcitygarage.com. Retrieved 17 April 2024.
  3. ^ Perschbacher, Gerald (11 January 2021). "Merger Mania: Nash and Hudson form AMC". Old Cars Weekly. Retrieved 17 April 2024.
  4. ^ Dworschack, Jim; Knutsen, Jerry (16 November 2020). "Nash engines". allpar.com. Retrieved 17 April 2024 – via The Nash Times by permission.
  5. ^ a b c d e Jennings, Tom; Swygert, Frank (3 December 2023). "Rambler 195.6 ci overhead valve six - Brief History". ramblerlore.com. Retrieved 17 April 2024.
  6. ^ "Early History of AMC (Official American Motors History)". southernclassic.tripod.com. Retrieved 17 April 2024.
  7. ^ a b Nash: Specifications for 1946 (PDF), Detroit, MI: Nash-Kelvinator Corporation, August 1945, pp. 4, 14–16, archived from the original (PDF) on 27 June 2024
  8. ^ "America's First Die-Cast Aluminum Engine (from: (1993 Rambler Reader, Vol. 14 No. 2)". amcrc.com. Retrieved 17 April 2024.
  9. ^ 1950–1965 Nash/AMC Technical Service Manuals
  10. ^ 1963 Rambler American Technical Service Manual. American Motors Corporation. 1962. p. 2.
  11. ^ Jennings, Tom (3 June 2022). "Rambler 195.6 OHV engine Cylinder Head". ramblerlore.com. Retrieved 17 April 2024.
  12. ^ Jennings, Tom (3 December 2023). "Rambler Lore: Introduction". ramblerlore.com. Retrieved 17 April 2024.
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Wikimedia Commons has media related to Nash Rambler engines.
  • 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
  • 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
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