According to Wikipedia

a 200 HP 258?   when the 304 made 210 HP in 70-71. then the 304 makes 150 HP in 72.   I think you need to have your eyes checked.

Those HP and torque figures and rpm sound more like 304 figures,  though a little low.

Edited by tyrodtom - Dec/04/2016 at 2:45pm

Wikipedia IS usually a good source. The Wikipedia article is correct AFAIK. The specs Gelalthedamned posted are for the VAM 282 (Mexican), not the AMC 258.

One thing though, GROSS hp is 1971 and older, NET hp is 1972 and later for US products. Apparently VAM used the older gross rating system longer, with the split being 78/79. The 282 used the 258 crank but had a larger bore. VAM 252 used the 232 crank and same bore as the 282. VAM cast their own blocks from AMC cores, so it was easy for them to make the bore bigger. Not sure if they made the cranks down there or not, but it's still cheaper to change the block casting than crank. VAM needed the extra displacement because they didn't make a V-8 and the high altitude near Mexico City. The factory was in Lerma, right outside Mexico City.

For those who don't know, VAM is "Vehiculos Automotores Mexicano". It was a joint venture between AMC and the Mexican government.

Frank pretty much said everything that had to be said.

Those specifications belong to the VAM 282 six, not to any of the AMC sixes.

The Gross rating system that AMC (and all of the US auto industry) used until 1971 was still used under VAM until 1978. I don't know if it's the same case for the rest of the makes in the Mexican market of the era. VAM used the net rating system for the first time in the 1979 models.

The VAM 282 was rated 200 gross horsepower from 1971 through 1978.

Estimated Net figures for those engines are as follows:

The 1971-1973 units with 9.5:1 compression ratio, steel intake manifold, points ignition and Carter ABD carburetor (360 CFM) had an estimated 145 NET horsepower.

The 1975-1976 units with 7.7:1 compression ratio, steel intake manifold, electronic ignition and Holley 2300 carburetor (350 CFM) had an estimated 120-125 NET horsepower.

The 1977-1978 units with 8.0:1 compression ratio, aluminum intake manifold, electronic ignition had an actual 132 NET horsepower (350 CFM Holley 2300 carburetor) in 1977 and an actual 129 NET horsepower (325 CFM Motorcraft 2150 carburetor) in 1978.

I do not have information in regards to an aproximate net figure for the 1974 282, which had 8.5:1 compression ratio, steel intake manifold, points ignition and a Carter ABD carburetor (360 CFM). I can only speculate it sits at some point below or above 130 hp.

VAM kept on using the 132 hp figure from 1979 through 1981 for marketing reasons, until they decided to show th actual 129 net hp figure for 1982.

VAM did produce crankshafts in the Lerma engine plant.

For more information on the VAM 282 visit a topic in this very subforum titled Mexican Engine Heads

Still though..the drop of horsepower over the years, I don't get it. Is it purely compression related? Like why is a stock 73 meaner than a 77?