Do cam swaps help economy?

If they do, does it depend on how hot or mild the cam is?

the longer duration the more gas will enter the chamber, from my experience, yes

before swap i was getting 20-22 mpg, now i'm getting 16-18 mpg

8) yes a cam swap can help improve fuel economy. for instance i had a stock 289 in my 66 mustang many years ago, and the best fuel economy i got was about 16 in town. after a cam swap i was able to push that to about 19 in town. you do have to be careful not to goo too big on the cam though. you need enough cam in the right rpm range to improve power and efficiency.