Carb Fuel System

I need some help setting up my carb fuel system. The manual is setup for EFI, and I think it has errors as well as not pertaining to carb systems.

I drew this to help the discussion. The top tank is the one with the mixing pot built in, denoted by the vertical line and the additional length. I'm not sure what to do about returns and I know I don't need the carbon vents so I suggest plugging. Any suggestions on the setup?

Also, to avoid confusion the tanks already have vents for air, don't confuse these with the carbon vents I'm suggesting plugging.

Ron


[ December 24, 2002: Message edited by: Ron Earp ]

[ December 24, 2002: Message edited by: Ron Earp ]

Ron,
If I was doing this for carbs, I would eliminate the low pressure pumps and feed the lines directly to the High pressure pump. I would install a filter at each tank exit. The swirl tank becomes useless. I would just plug it up. Both your gauges will still work. You can install a late model pickup truck auxillary tank switch if you prefer to not have both tanks feed at the same time. To me this makes things simple and easy to convert back if you ever want EFI. The only thing you really would have to do is make sure the fuel pump is located near the bottom of the tank level. You don't have to but it makes it easier for the pump to siphon if you run low.

Hersh

PS...I really don't see a problem with fuel starvation from roadracing because of the shape of these tanks. If you were to really get serious about road racing then perhaps you could run the main lines from the tanks to the swirl pot then to the pump. You still wouldn't need but one of those LP pumps to get the fuel to the swirl pot.

[ December 24, 2002: Message edited by: Hershal Byrd ]

Ron,

I agree with Hersh, except for one thing.
Be sure to put a LOW pressure pump in, as carbs require somewhere between 4-7lbs of
constant fuel pressure. A high pressure pump
will blow the needle valve seats of your carb, loading the cylinders full of raw gas, among other things, ie, washing cylinders, etc. You could add a pressure regulator after the high pressure pump, but a low pressure pump would be better.
A tank changeover valve, a low pressure pump, and inline filters are all you'll need.
I have inline filters on each tank line before the changeover valve, and between the fuel pump and the carb.

Bill

All pumps are Holley blues suitable for carbs. 3-7 psi as mentioned is all that is needed, none will be high pressure pumps.

Ron

Ron,

We have done this and we used two lift pumps (low volume Holley pumps) dirrect from the normal pick-up point of the main tanks. These were connected through filters to a "T" piece and to the engine via a pressure regulator and pressure gauge. The system was fitted to a Webber set up and works well but can suffer from fuel surge.

If you want to get realy serious and hit the tracks hard than use the tripple fuel pump system WITH the overflow system as per our injection system. Basically replace the injection pump and filter with low volume modles, leave the rest of the system alone.

Best wishes,

Robert

ttt