Power valve missing spring ***'y ... why?

How? The only place it could go is the float bowl. Whoever had this carb before either took it apart and didn't notice it, or did it on purpose. I am just wondering what that purpose might be. It was weird. Since I rebuilt it, the car runs smoother than it ever has and the throttle response is immediate. I don't know if I'm imagining it or not, but it seems to have less power. I went from 75 primary jets to 72. I may switch back and see if I feel the difference.