AN-6 or -8 for My Fuel System (SBF)

[FireSale]

I'm ready to order all I need for the fuel system on the GT 68 Coupe I'm working on and want your opinion on -8 (1/2 in) as opposed to -6 (3/8 in) through the fuel system. The difference in price between the two is about $170, which is doable for me. The carb has -6 inlets but I can make everything else from the fuel cell through the filter, pump and line either -6 or -8. Do the -6 inlets on the carb cancel out the benefits of the larger supply lines? It will all feed a BOSS 302 through a QF 780.

Thanks.

Dale

[james schaechter]

Fuel systems are just that. Take some time to evaluate the entire system, pump, lines, filters, regulator.
What is the combo? Stick or auto? It all has to work together. I would think that a Boss anything would be very thirsty and need a well thought out system. I doubt if a dash 6 anything would be considered in any serious effort. The size of the line won't help if the pump is not up to it.

[rallye bob]

Do it once, do it right.... -10 from cell to regulator...

[FireSale]

The larger fuel pump is a Quick Fuel with a 20 psi max and a flow rate off 175 gph. The filter is a Magnafuel inline with a 25 micron screen. The little guy on the list is a Holly Blue that is 14 psi and 110 gph.

EDIT: The QF has a built in regulator at the return line port and a fitting for a pressure gauge. One stop shopping. Should I still have a regulator and gauge at the carb?

Dale

[FED 387]

get rid of the BLUE Holley Reg to start with use an Aeromotive/Weldon/MagnaFuel or something similar---use AN -10 from tank to regulator and then AN-8 from reg to carb-- you can get fittings for the carb that are AN -8 or you might need to use an adapter or fabricate one if need be---ya got a long run from the back of the car lotsa bends and turns in the hose and when the car launches the pump must overcome the tendency for the fuel to want to rush to the rear instead of going forward to the carb---don't cut yourself short as others have said do it right the first time---my 2 cents--FED387

[Bob Bender]

Originally Posted by FED 387

get rid of the BLUE Holley Reg to start with use an Aeromotive/Weldon/MagnaFuel or something similar---use AN -10 from tank to regulator and then AN-8 from reg to carb-- you can get fittings for the carb that are AN -8 or you might need to use an adapter or fabricate one if need be---ya got a long run from the back of the car lotsa bends and turns in the hose and when the car launches the pump must overcome the tendency for the fuel to want to rush to the rear instead of going forward to the carb---don't cut yourself short as others have said do it right the first time---my 2 cents--FED387

Thats what I have !!

[Mark Ugrich]

Run the largest pump and lines you can afford.-8 minimum,-10 if you can. It's possible to starve an engine for fuel and not even know it.The closer the regulator and fuel pressure gauge are to the carb,the more accurate they will be.

[FireSale]

I did a simple statistical survey of regulators available at Summit and found that of the units adjustable down to between 3 and 5 psi 6 were -8 and 26 were -10 on the inlet side. Since being able to adjust down into this range is important for a carb engine, it's obvious that I need to use -10 line and pump. But I'm not going for the throat on the pump. The MagnaFuel 275 will do fine.

Now I get to crawl around under the thing with string to measure for line.

Dale

[FED 387]

Simple thing to remember Carbs work on demand Fuel Injection works on pressurized supply-- also remember that Volume is not the same thing as Pressure---If you understand how a carb works many of the problems will either never happen or can be fixed with out too much difficulty.---FED 387