AMC Engine ID Information
AMC Engine ID tags are small thin metal tags attached with a Phillips screw on the passenger side valve cover facing the radiator. This tag will give you the engine build date and engine. Unlike other auto manufactures AMC did not have any numbers on a particular engine that corresponds to any numbers on a particular vehicle. Tags often are moved from engine to engine or removed when aftermarket valve covers are installed.
Starting in mid 1969, the cubic inch displacement number was cast into the side of the block under the motor mount bracket. This is usually the best way to ID a AMC block as they look all the same from the exterior other than this
Below is a breakdown on the numbering system used on AMC valve cover metal tags.
1st Digit is the YEAR
| 1 = 1968 | 4 = 1971 | 7 = 1974 | 1 = 1977 |
| 2 = 1969 | 5 = 1972 | 8 = 1975 | 2 = 1978 |
| 3 = 1970 | 6 = 1973 | 9 = 1976 | 3 = 1979 |
2nd & 3rd Digit is the MONTH
| 01 = Jan | 04 = Apl | 07 = Jul | 10 = Oct |
| 02 = Feb | 05 = May | 08 = Aug | 11 = Nov |
| 03 = Mar | 06 = Jun | 09 = Sep | 12 = Dec |
4th Digit matches 7th Digit of the VIN
| A- 199 1 bbl (70) | M- 304 2 bbl Low Comp. (71-74, Jeep ONLY) |
| A- 258 1 bbl (71-79) | MX- 242 MPI (4.0L MPFI, 86-01, Jeep ONLY) |
| B- 258 1 bbl Low Comp. (71-74, Jeep) | N- 290 4 bbl (68-69) |
| B- 151 2 bbl (80-83, GM 2.5L) | N- 360 2 bbl (5.9L, 70-91) |
| B- 126 Diesel (85-87, Renault 2.1L, Jeep XJ) | P- 360 4 bbl (70-77) |
| C- 258 2 bbl (4.2L, 76-89) | R- 134 1 bbl (70, F-head, Jeep ONLY) |
| E- 232 1 bbl (70-79) | S- 343 2 bbl (68-69) |
| F- 232 1 bbl Low Comp. (71-74, Jeep ONLY) | T- 134 1 bbl Low Comp. (70, F-head, Jeep ONLY) |
| F- 145 Diesel (81-86, Jeep ONLY) | U- 150 (84-01, AMC 2.5L, Jeep & Eagle ONLY) |
| G- 232 2 bbl (70-74) | W- 390 4 bbl (68-69) |
| G- 121 2 bbl (77-79) | W- 173 2 bbl (84-86, GM 2.8L V6, Jeep XJ ONLY) |
| H- 290 2 bbl (68-69) | X- 390 (70) |
| H- 304 2 bbl (70-79) | Y- 390 (70 Machine) |
| J- 199 1 bbl (68-69) | Z- 343 4 bbl (68-69) |
| L- 232 1 or 2 bbl (68-69) | Z- 401 (71-77) |
Here is a sample valve cover tag:
Sometimes you also find other letters on the tag that signify any oversize or undersize pieces AMC used:
| B=Cylinder bore .010 oversize | C=Camshaft bore .010 undersize |
| M=Main bearings .010 undersize | PM=Mains & Rods .010 undersize |
| P=Connecting rod bearings .010 undersize |
I really enjoy the engine identifying . I am picking up a ’55 cj5 today with a v-8 engine that I have yet to identify …
I have no engine tag on the valve cover as it’s been changed out. There are some other numbers beside the 401 on the block. Can these be used to identify the year of the block?