I just got a 76 mustang II, i was doing some research and found that the 5L v8 only makes 140hp.
anyone familiar w/ mustang IIs can help me understand why this is?

 

Arin can help you with that. but it had to be because of the fuel crisis in the 70's. the 5.0/302 in the II was weak, to say the least compared to what it used to be and what it later became.

 

Technology of the day and the hard crunch on emissions.

 

Yup I had a Mustang II Cobra II with the V8. Back then it was just norm for all the V8's to be suffocated. It wasn't until the 1982 GT that the horsepower race was resurrected.

A lot can be done with the V8 you have if you make the right mods.

 

Suffocated is the correct term.
The heads and intake had about as much flow as a drinking straw.
It was a quick fix to increase gas mileage without doing any real engineering.
Back then, we had just gotten over a period of time when sometimes you couldn't even buy gasoline and the price had doubled when it became plentiful again (think $6 dollars a gallon if it happened today).
They had to do something about fuel consumption fast.