AMC Coupes/Sedans/Wagons 1975-1988 Repair Information

Engine

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4-121 ENGINE



See Figure 1

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Fig. Fig. 1: The engine identification number is located on the left side of the block4 Cyl 121 engine

The 2-letter, 6-digit serial number is stamped on a machined pad on the left side of the block, just in front of the clutch housing.

4-150 ENGINE



See Figures 2 and 3

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Fig. Fig. 2: The engine identification number is located on the right side of the block4 Cyl 150 engine



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Fig. Fig. 3: The oversized/undersized component code is located just above the oil filter4 Cyl 150 engine

The engine serial number for the American Motors built 4-150 is located on a machined pad at the rear right side of the block, just below the head.

Also on the block, just above the oil filter, is the oversized/undersized component code. The codes are explained as follows:

B: cylinder bores 0.010 in. (0.254mm) over

C: camshaft bearing bores 0.010 in. (0.254mm) over

M: main bearing journals 0.010 in. (0.254mm) under

P: connecting rod journals 0.010 in. (0.254mm) under

4-151 ENGINE



See Figures 4 and 5

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Fig. Fig. 4: Location of the engine identification number and if applicable the stamp for vehicles built in Georgia and Tennessee4 Cyl 151 engines



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Fig. Fig. 5: English To Metric Conversion: Mass(Weight) and Temperature

A three character code is stamped into the left rear top corner of the block on these GM built engines. Additionally, engines built for sale in Georgia and Tennessee have a non-repeating number stamped into the left rear block flange.

6-232 & 258 ENGINES



The American Motors engine code is, of course, found in the identification plate on the firewall. The second location is on a machined surface of the block between number 2 and 3 spark plugs. For further identification, the displacement is cast into the side of the block. The letter in the code identifies the engine by displacement (cu. in.), carburetor type and compression ratio.

On vehicles equipped with the 6-232 made prior to 1971, the engine code number is located on a machined surface, adjacent to the distributor. The letter contained in the code number denotes the cu. in. displacement of the engine. The letter, L, denotes 232 cu in. 8.5:1 compression ratio. The engine code letter is located on a boss directly above the oil filter.

On 6-232 engines built before 1971, the size code is stamped on a tag located on the left front side of the baffle above the intake manifold below the build date, and on the boss above the oil filter. The following chart explains just what the letters indicate on the 232 sixes made prior to 1971:

First DigitSize of the bore: A, B, or C

Second DigitSize of the main bearings: A, B, or C

Third DigitSize of the connecting rod bearings: A, B, or C

A - Standard; B - 0.010 in. (0.254mm) undersized; C - 0.010 in. (0.254mm) oversized

All of the engines made after 1971 have the same undersize/oversize letter codes, located on the boss directly above the oil filter. The parts size code is as follows:

Letter B indicates 0.010 in. (0.254mm) oversized cylinder bore.

Letter M indicates 0.010 in. (0.254mm) undersized main bearings.

Letter P indicates 0.010 in. (0.254mm) undersized connecting rod bearings.

Letter C indicates 0.010 in. (0.254mm) oversized camshaft block bores.

8-304, 360, 401 ENGINES



On American Motors built V8 engines, the number is located on a tag attached to the right valve cover. For further identification, the displacement is cast into the side of the block. The letter in the code identifies the engine by displacement (cu. in.), carburetor type and compression ratio.

All of the engines made after 1971 have the same undersize/oversize letter codes, located on a tag next to the engine number. The parts size code is as follows:

Letter B indicates 0.010 in. (0.254mm) oversized cylinder bore.

Letter M indicates 0.010 in. (0.254mm) undersized main bearings.

Letter P indicates 0.010 in. (0.254mm) undersized connecting rod bearings.

Letters PM indicate a combination of the above specifications for P and M.

Letter C indicates 0.010 in. (0.254mm) oversized camshaft block bores.

 
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