Amc258 J Series Engine

What's the deal with the j series trucks 258 I've read compared to later years this engine outperforms on torque curve and hp. Read it On jeeptech.

 

The J-trucks and Wagoneers got the 2V BBD sooner (1977) than the CJ (1979). AFAIK there is no other difference.

In this era, any later engine will be more strangled than an earlier engine. Emissions laws get stricter as time goes on, and power ratings go down. At some point, technology catches up and power increases.

 

Additionally, the way engines were rated for HP and torque changed around 1970. Prior is gross HP, and after is net HP. Likely there is no actual difference between say, a '70 and a '72 engine, except for the rating system.

I would guess that these ratings on Jeeptech come from sales literature. Would not assign too much authority to them without better details (citations).