Just to back up what has been said;

Use Nickerson carb. I used an 800 Holley and had approx 10-11# in the box and 8-9# in the manifold. The carb could still be modified further to accept more boost.

I've only used a single plane intake. They are designed to move more air to start with, especially in the higher RPM range. With forcing the air in, and moving more air even in the low RPM range I prefer the single plane.

Reference your REGULATOR FROM THE BOX and mount it as close to the carb as possible! The boost pressure in the box is what your fuel pump has to fight against to deliver the fuel.
I liked to set it at 8#, for safety. However, 6-8# will be fine.
Get a fuel pressure guage. The guage will read static fuel pressure plus boost pressure.
I had two boost guages. One in the box and one in the manifold. The one in the box was helpful in many ways. The biggest was the ability to cross reference it with the fuel pressure guage.
Example; Static fuel pressure is very important. If the box pressure is say, 10 but the fuel pressure guage is only reading 15, you're only getting 5# of fuel pressure.
If you put an additional boost guage in, put it directly under the carb and that, of course, with read boost in the engine. It will be approx 2# lower than what's in the box. It will also act as another cross reference point.

Definatly do not, DO NOT, use a carb hat. Use the box, for reasons stated by COBRA MARTY.
When you buy the carb from Nickerson he will have the solid floats in the carb and everything will be set up perfectly.
Oh, make sure you have 4 corner idle. It's the way to go. It will start and idle like an efi.

DAVE

Thanks guys for the help on this stuff. I feel a bit better about doing this now. I didn't want to get into this new adventure with bad results from what I have going now. I will call Dean tomorrow to get the ball rolling and try to get a box and other parts ordered. I'm sure there will be a few more questions about this in a few weeks when I start tearing her apart. I guess it's time to put a for sale sign on my EFI stuff . Thanks again-you guys are the best . Here I go again-Wish me luck! Scott

Hey Scott,
did you decide against the F.A.S.T. ECU? Sounds like a step backwards in a sense but probably easier I suppose. If you had the FAST you could just get rid of the boost referenced regulator all together. Just run a 43.5 psi constant with 65-72 lb injectors. The FAST could tame the idle fine at that point.
Not sure I understand why the Aeromotive pump is not giving you what you need. Isn't it suppose to support well more than is needed? Just curious because that's what came with my kit.

Does anyone know where to get a nice carb/throttle body cap for a standard 5-1/8 flange?
Later
Dave

Sorry Baja !! I was out of town & missed your reply & question until today. I used to have a carb'd procharger that was absolutely reliable. I now own twins with efi & one engine & regulator keeps changing pressures hour to hour. down to 30# & up to 50#. This really messes with reliability & EGT temps. Also melts stuff!! This is kill'n me, I think I also want to go back to carb's!! Never a worry about an injector, pressure or a dry/lean cylinder again!!!
Of course, in tearing it down to do that, well maybe a cam & some rollers & maybe roller rockers,,,,, you get the picture!!

NordicHeat, I can't argue with the fact that the SpeedPro/FAST is the super setup on any motor. The problem is, I bought this to use for my Mustang project($2500.). I'm hoping that the EFI stuff I'm using on the boat now will get a good buck to cover the conversion. I will spend a ton more money for new injectors, SpeedPro and new pump than with the carb setup. I do believe that my pump is taking a chit too! That pump is rated for 1300hp carbed, 1000hp fuel injected and 700hp efi blown. A bunch of people don't realise that with this pump.
Going to a carb will give me the freedom to set my rev limit to whatever also. If I want to run faster and the motor has the power, all I have to do is change the chip(within limits naturally). This also works for not buying a new prop. I'm referencing all these thoughts with the equipiment on the boat now, not the FAST system.
I'm getting some good feedback from carb users also. I talked to Brad Nickerson today and he told me they are testing a new Vortech carb motor that made 825hp on a 454mag with 8psi of boost. That's with a healthy cam, cleaned up stock heads and a single 800cfm carb. Those are some big #'s and would be hard to match on a MEFI3 system. I just wanna try something else.
Bottom line is that you have a good setup that will take you only so far. Unfortunately for me it just aint enough. Most people would be thrilled to have a boat as fast as mine, but I have a real problem with knowing when to quit .
To wrap it up-I aint rich and I aint poor but it's still about the money!!! I should have just started with that statement !
Good luck with your boat! It's going to run great for you. Scott

Blown Formula, Not a problem! You gotta work to play right? Is your fuel problem happening on stock motors and regulation? If it is you may want to check your fuel/water separators for dirt. These units have a recirculation system that is used in replacement for an actual return line to the tank. That unit uses an orifice to draw a vac from the fuel flowing by it to suck the excess fuel back into the main feed line for fuel. If there is something blocking the orifice then the pressure will spike because it can't be returned. I believe there are 3 lines on these goofy separators. I know that sounds dumb but it's one of those stupid things that comes to mind when all else fails and it's free. Another free thing to do is check the volt meter and see if that changes when your fuel pressure changes . Good luck and let us know what you find. You can't be the only guy with this problem.
I'm going to start ordering parts this week . I'll keep you posted! Thanks Again...

Hey Scott,
very interesting on the fuel pump rating. I'm assuming that the reason they rate it way down on EFI blown application is because of the high pressure (65+ pis) required by some blown applications. It would be hard for any pump to deliver that much fuel and retain that kind of pressure. Again, I'm thinking that with standard EFI pressure of 43.5 that the pump would be rated the 1000 hp. Not that I'll ever pump it up that high but nice to know. I may give Aeromotive a call. Also my injectors are rated to 1000 hp at 80% duty cycle with only 43.5 psi so that should help also.
I'm not looking to make more than 750hp with my setup but I think the possibility would be there if I ever got a new outdrive

I'm using a single plane, Dart type intake with the throttle body on top. Should be a lot of potential hp there.
Thanks for the info on the pump.
Later,
Dave

baja**** I changed the fuel/water seperator 1st time. This last time may really cost me !! this engine started acting funny by running 600rpm faster than the starboard side w/same throttle setting. I adjusted it back 3 notches for the last mile home, opened the engine bay & had 4 1/2 qts. of oil sprayed over the inboard side of the port engine! I cleaned it up, refilled the oil & started it. It sounds ok, & no oil leaks???? All pressures appeared normal when the engine speed changed (600 rpm), but on restarting the fuel pressure was only 30-35#. What the chances I have a burnt piston?? I gotta plug the plugs this weekend to find out. Yes, this is a stock (rebuilt by AZ Speed) less than 10 hrs ago.....454 Mag efi....or was until now.!! First the distributor gear went south & now this!! Disgusting!!

Blown, I dont believe you did any harm at those fuel pressure settings. That's providing that the last mile was not wide open throttle. If you have stock manifolds(exhaust) then those motors are running rich to begin with at the factory setting(42-45psi?). Another added bonus is that the knock sensor would have retarted the timing if it found some detonation under a lean condition. Are you using the reulators from AZM that bolt on to the cool fuel with the hat that squishes over the factory reulator? If you are then check those things again. If I can recall correctly, when you do this mod the hat that gets bolted on is not to be overtightened. This will mess with the consistency of how these things work. The directions give you warning of not to over do it when you screw the hat back together.
As for the oil thing I'm not sure what you were getting at by telling me what happened. Were you just telling me or did this have something to do with the low pressure-Sorry . Keep me posted. Scott

Venting Baja, just venting!! Ever since I bought this boat, it has been one thing after another, but only on the port engine!! It's driving me crazy.....engine dies at idle, engine dies going into gear, increase idle speed, still happens, running across the lake at 3000 rpm & engine dies....restarts ok and fine for awhile. then the fuel pressure starts fluctuating, then the oil comes out....where does it all end!! I'm ready.
If this was a carb'd/blower box engine I would know what to do. Here, I'm lost. Not even the Merc mechanics could fix the idle & dieing problem. This is why I was talking about going back to carb's.