Why are 318's low HP and torque?

The 1970 factorie hp rateing for the 318 2 barrel dodge was 235 hp and the 1972 340 4 barrel was 245. The 318 had compression the 340 had carb,cam, and a pretty good heads on it. So a 1970 318 with carb,cam,and air sould make closet to the same as hp the 340's