I am ready to replace my stock carb w/ something that will make some serious difference. My engine is all stock 1994 454 mag merc. What would be the best way to go to get more performance? i was looking at holleys, but i'm not really sure......please help me guys!!! Thanks

Make sure to check out the Demon carbs by Barry Grant.

Most likely your current carb is either a Weber or a Rochester. A Holley will not fit on either of those intake manifolds without using one of those adapter plates. The bolt pattern and hole in the manifold iare different. Unless your old carb is worn or needs rebuilding, replacing only the carb will net you nothing in speed. If the motor runs fine with the old carb, leave it alone. If not call Dean or Brad @ Nickerson Performance, they can set you up right the first time.

My Stock Weber Carb Was Rebuilt 3 Months Ago, But It Still Won't Put Out. The Shop That Rebuilt It Must Have Done A Terrible Job B/c The Inside Of My Carb Has A Rust Build Up In It. I Tried To Get It Off, But It Comes Right Back. I Ran My Boat The Other Day And She Was Surging A Good Bit. The New Carb Is Just The First Step Of A Few Upgades. Any Suggestions Are Welcome....thanks Guys.

A carb won't make a "serious difference" in performance unless the one on it is way wrong.
A Holley carb will bolt up to a magnum intake just fine without an adapter.

Have seen very good results with Rochester, even better than Holley on 454s but they are a pain to set up. Very few people know how to do a Rochester, Holley is more commonly used and more people know how they work.

I would look on the intake manifold where the carb bolts up (flange) and see if there are two different bolt hole patterns. It seems that if I remember correctly that is probably what you will find although you still MAY need a 1" adaptor in order to use a Holley----if that is the case it;s not a big deal. A 750cfm Holley would work fine in your application, but wouldn't go over an 800cfm on your 454cid as you don't want to over carb.

Also, if you're still running the bone stock Merc exhaust manifolds (which are very crude) it would be a good thing to replace them with an aftermarket set of exhaust manifolds and stainless tailpipes. I prefer the Stainless Marine exhaust manifolds---it's a very good design, very durable, and affordable, but in your case probably just about any manifold design will help. Aftermarket exhaust manifolds are usually cast in aluminum so they are MUCH lighter than the stock Merc cast iron manifolds you have now. They will also dress up your engines much nicer and will give your engines more of a rumble tone/sound if that is what you like. You probably are not going to see much difference in speed (if at all) by just changing out a carb and exhaust system, BUT every little bit helps especially after adding the aftermarket exhausts you will most likely notice a slight increase in RPM, better performance, and throttle response in the midrange.

If I'm not mistaken, the '94 motor will have the small peanut port heads. If you're interested, I've got a pretty fresh set of vortec oval port heads that I'll sell you cheap.

As far as carbs, I went with the Sea Demon 750 on mine.

I AM LOOKING AT THE SEA DEMON 750 W/ ELEC. CHOKE:
http://www.flatlanderracing.com/carbsdemonsea.html
DO YOU LIKE YOURS? ALSO HOW MUCH YOU ASKING FOR THE HEADS?
I REALLY WANT A NEW CARB....THE ONE I HAVE NOW IS CRAP....SO THANKS FOR THE INFO GUYS.
ONE MORE THING....THE BEST PRICE I FOUND ON THE SEA DEMON IS $492.00.
ANYBODY KNOW A CHEAPER PLACE?
THANKS

The rust inside, is that in the float bowls? If so, you may have a problem with rust in the tank or lines. There's actually not much to rust inside a carb.
Also, if its a weber (Carter AFB, squarebore), a holley or deamon will bolt right up, but you will need to bend a new hard fuel line. If it's a Qjet (speadbore), an adapter or new manifold will be needed. In either case a new manifold wouldnt hurt, especially if you plan a new cam, head work, exhaust, etc.
Gary