How do you find out the oringal horsepower a 390 big block has?

Answer 1

You need to post what year it is and what car. Some 390's made 335 horsepower and other ones less. Some years the horsepower went up and later on it went down. You also need to post if it is like one four barrel carb or two. Post as much info as you can and try a Google search like: 1967 Ford Fairlane 500 390 GTA horsepower and you may find an enthusiasts website that hasa all that info. The 390 was in American Motors AMX, Javelins, Ford put it in Galaxies, Galaxy 500 XL's, Fairlanes, Mustangs, Thunderbirds, and Mercury put it in some of their rides like the Mercury Cyclone too and it was even in some trucks as well.