Re: water intake screens 73 85hp
No need to take the carbs off. Just use a flex socket on a long extension to reach the disconnect screw.
The screen will come out once the water pump is off. I don't know if it applies in this case, but I believe on some models you have to remove the seal housing below the pump because the screen won't go past it.
The screen snaps in place. Easiest way to get the old one out is to break it and fish out the pieces. Push the new one in till it snaps and you are set to go.