What Carb Do I have and need
 

Got 91 454 mercs the repair manual says Holley. But the ones I have dont say Holley or look like a Holley. They had something written that started with a UA?? And Said rochester on the side.

Sorry Im to young and Carbs are foreign to me. Either way they are a two barrel now and I want a four barrel and the ones now constantly drain and take forever on start up. How do you go about knowing what Carb to get. Any Sizes or brand reccomendations?

Any disadvantegs with going to a 4 barrel.?

Not a two barrel
 

You have the Rochester Quadrajet four barrel (no 454 ever came with a two barrel). I highly recommend that you keep this 750 CFM carburetor, it is more durable and more trouble free than the Holley four barrel for marine use (and performance is the same). It is much more fuel efficient at low speeds also.

The Mercruiser/Weber four barrel has a reputation for being hard to start after sitting for a few weeks. They are the same as the Edelbrock marine carburetor.
Dennis Moore