I have twin 330 mercruisers, I need to rebuild carb's, I was wandering if going to holleys would be a better choice? if so would a 600c.f.m be big enough?

The Quads on your motors are a perfect carb for the application. swapping to 600 or so holleys would gain you nothing and cost you plenty. Those q jets can flow big power if the rest of the engine can make use of it. You could use them to make 400hp plus if cammed correctly. Save the bucks and rebuild them, they are simple to do if you can follow the instructions that come with rebuild kits. replace the floats at the same time and whatever you do, DO NOT LOSE the little spring under the primary power piston( the thing with the needles hanging on it. They are a nightmare to get replacements for.

I would stick with what you have!
Unless you want to start fooling around with new fuel lines, and possibly having to play around with jetting. Holleys are great but do require a considerable amount of tweaking.
Rebuild your existing carb and forget about it!!!!!
Good Luck
Brian

Thanks for the advice, that's all I needed, I will repair the quad's. Thank's for the input!

I have quadrajet, which my boat mechanic frequently called quadrajunk. Maybe he was screwed up, but it seemed that it was never set right, either it'd bog down really bad coming out of the hole from too much fuel, or not open up enough to pop out at a reasonable rate. What's up with that??

A major mistake made rebuilding these carbs is the lead plugs in the main body leak and create vacuum leaks. Get some 2 part epoxy and neatly apply over all the lead plugs.

I've used both. I like the better mid range feel and the improved tuneability of the Holley. More power ? Maybe not at WOT, but maybe at cruising RPM. Just seems a better carb for a boat. Smoother feel all around.

I am new here .. but how would you know that when you don't even know how to change your engine oil?

Duh !!

Goes to show you how much you know. If the dip stick was installed incorrectly the level would be low... Post#1? Good start. We all know who you are because you were spotted on the freeway towing your hobie cat with the '82 chevette.

Q-jets are prone to leaks at the bowl plugs under the base. They should be epoxied when you have them off. They are also almost as infinitely tunable as a Holley if you know how. For the bogging problem the secondary air flaps need to be tightened up just enough till the bog goes away, simple to do but lots of people don't know how. Some of the crispiest throttle response I have ever seen has been with a Q-jet. Those that know them love them, everyone else rebuilds their Holleys every year or so