Lets hear what you all think on this topic.  I am a small block ford guy, I have been building my own motors and racing for about 15 yrs or so. I have a 408cid small block for I run in my mustang that made a dyno proven 644hp @6900 rpm. That motor could never survive on the fuel system that my boat has. Here is the link to my boat http://www.socaljetboats.com/index.php?topic=7110.0

   As you can see its a pump gas bbc with a tunnel ram and dual marine 750 holley carbs. The fuel system is the stock fuel tanks whitch I believe are 3/8 outlet to a switch that is 3/8 as well. I have -6 line going to a holley mechanical 140gph fuel pump then -8 to the fuel log in front of the intake manifold then -6 to each fuel bowl. I figure the motor makes about 600 - 620 hp and it runs a gps 84mph at elsinore in good water. The problem I have is the plugs show a touch on the lean side no matter what jet I seem to throw at them. My cylinder head guy seems to think because i am puling fuel from 4 bowls instead of 2 I have enough volume to supply the motor what it needs. I dont have a drop in fuel pressure but I do know pressure is not volume. What do you guys think about this? Before I fuck the motor up should I change the fuel system around? I was thinking of this set up. I can keep the tanks the way they are and have both lines going to this fuel block eddie marine sells http://www.eddiemarine.com/store/cart.php?m=product_detail&p=11895&c=127

I have a aeromotive pump already and i can have both lines from the tanks go to the fuel valve and that should give me enough volume to supply the electric pump. If the tanks draw unevenly I can just switch over to the tank that has the fuel and limp back If I need to. The valve can pull from both tanks or each tank individually. Or is my cylinderhead guy right, what I have is enough 

I guess your right, I would love to duplicate the scenerio on the dyno to see if the theory of the extra bowls of fuel is true. Is there anyone else out there runnind the stock tanks like that?

I had a similar situation where I was not getting and holding enough fuel pressure. So I changed to a Holley mechanical 110gph fuel pump and changed my whole line setup. I started with my tanks, they had 1/4 bungs on the tops of them that went straight into 90's. So I eliminated the 90's and got a hose barb that threaded onto my 1/4 bung and had a 1/2 hose barb on the other side and i ditched the 90's b/c I had enough room for the hose to acutally make the turn under my deck. After that I took both hoses into a nice little homemade tank seperator switch I made (total garage build but not too bad) Picture below.

Then from the splitter I kept the 1/2 lines to the pump and from the pump I went into my PermaCool fuel/water seperator filter. Then from the filter I ran a -8 line upto another Y with a gauge and two -6 lines up to each end of the carb.

My main goal was to eliminate all 90's and T's and any other thing that would restrict flow in anyway. I also went with 1/2 lines thinking that if anything I would have extra fuel sitting in the lines at all times.

Now I know I am not a pro by any means, but this the best I can do. I will know how it works after this weeknd. Oh yeah and these Y's were like $25 bucks on JEG's and the brass all came from home depot, much less than that $130 Eddie marine piece, but not as clean I guess.

Whata ya think?