"AMC Engines, 1967-1974, by Horsepower rating" NOTE: Subtract 20% from the 1967-71 engines for a more accurate comparison to the 1972-74 engines (see bottom for details). 1967 1968 1969 1970 1971 1972 1973 1974 HP size HP Torque size HP Torque size HP Torque size HP Torque size HP Torque size HP Torque size HP Torque size HP Torque 100 232-1v 100 185 232-1v 100 185 232-1v 100 185 110 258-1v 110 195 258-1v 110 195 258-1v 110 195 128 199-1v 128 185 199-1v 128 185 199-1v 128 185 199-1v 128 185 145 232-1v 145 215 232-1v 145 215 232-1v 145 215 232-1v 145 215 232-1v 145 215 150 304-2v 150 245 304-2v 150 245 304-2v 150 245 155 232-2v 155 222 232-2v 155 222 232-2v 155 222 232-2v 155 222 160 258-1v 160 245 175 360-2v 175 285 360-2v 175 285 360-2v 175 285 200 290-2v 200 285 290-2v 200 285 290-2v 200 285 210 304-2v 210 305 304-2v 210 305 220 360-4v 220 315 360-4v 220 315 360-4v 220 315 225 290-4v 225 300 290-4v 225 300 290-4v 225 300 235 343-2v 235 345 343-2v 235 345 401-4v 235 335 245 360-2v 245 365 360-2v 245 365 255 401-4v 255 345 401-4v 255 345 280 343-4v 280 365 343-4v 280 365 343-4v 280 365 290 360-4v 290 395 360-4v 290 395 315 390-4v 315 425 390-4v 315 425 325 390-4v 325 420 330 401-4v 330 430 340 Machine only 390-4v 340 430 All V8s assumed to have dual-exhaust if available Beginning in 1972, the engine power rating system changed to better reflect 'real-world' use of all engines. When comparing 1972 and newer engines (which have a 'Net' rating) to 1971 and older ('Gross' rated) engines, subtract 20% from the 'Gross' engines for a more accurate comparison. Example: 1971 401-4v, 330HP / 430# Trq GROSS minus 20%= 1971 401-4v, 264HP / 345# Trq NET (estimated*) which compares to 1972 401-4v, 255HP / 345# Trq NET So the 72 engine isn't missing 75HP from the 71. The real difference is about 10HP. (*The adjusted Torque of the 71 maybe a bit higher considering the '72 rates the same in this example) ------------------------------------------------------------------------ The difference is the technique used to rate the engines: 'Gross' ratings were made with the engine running on a stand, with no accessories attached like pulleys, belts, closed exhaust, etc. 'Net' ratings mean the tests were done with all this equipment attached, which better reflects how each engine will perform once actually in a car.