Difference between Marine and Automotive intake amp carb

" I have a 4.3 litre V6 in a 1

" I have a 4.3 litre V6 in a 1992 Sea Ray. It runs great, but I would like a little more power.
Replacing the two barrel carburetor with a four barrel seems about the easiest solution.
Question:
What is the difference between a marine 4.3 manifold and an automotive manifold?
What is the difference between a Rochester 4bbl quadrajet for marine applications and for automotive applications?

Also, does anyone have the manifold and carb I need for sale?
Thanks.
qd7 "

" Use caution here. Simply pu

" Use caution here. Simply putting a four barrel on an otherwise stock engine that was designed for a two barrel could actually hurt performance. If your engine and prop combination is running at the proper max RPM at WOT, I doubt a bigger carb will help.

Let's say your 2 barrel is rated at 400 CFM. If you put a four barrel on that is rated at, say, 650 CFM (a popular size) you will definitely have throttle response and fuel economy degradation. However, if the size difference is around 100 CFM and you add a bigger prop to the mix, you may get a few more MPH without exceeding the max recommended RPM for your 4.3 engine.

More power means either souping up the engine with things like a bigger cam, high performance heads, etc., or going to a bigger engine. Adding a bigger carb (and intake) to an otherwise stock engine seldom gains much power unless the original carb was way too small, which isn't likely here.

Marine carbs use "J" tubes or similar devices to vent the float bowl(s) into the carb throat, and usually have different vaccuum connections and linkages than automotive. Intakes for carbs are usually automotive pieces adapted for marine engines. "

" Never use an automotive carb

" Never use an automotive carb on a boat unless the motor is always exposed. Auto carbs vent to the atmosphere, and will fill your bilge up with gas fumes. BAD things happen when your bilge fills up with fumes!!!!!! "