I just had the guy building my motors order carbsand he bought automotive.
Can you use a automative carb on a marine motor
what is the differance?

Lots of people do run em. But be advised that Coast Guard and some more clued in lake/river patrols know the difference and can ticket you.

Also marine carbs and fuel pumps are designed to prevent fuel spills and subsequent explosions.

Also, I have heard that insurance adjusters love to find non-approved stuff when they are looking for an "out"

Barry Grant makes a sea demon that most seem to like amongst others.

The difference is that nobody will let you raft up next to them with your bomb.

I would get the marine carbs.
You boat in the enforcement capital of the world.