i've used the search but it seems that everyone there is asking about size of there return and also everyone has boost already running. setup is a 347 fuel lab pump. i'm running -10 from tank to second filter (post the pump) then -8 from there to the reg. and -8 from reg. to carb. i guess do i need to run the return line and if so, should i run -6 from the reg. to the carb and -8 from the reg. back to the tank?

 

WOW a little more details would help. definitely don't downsize reg to carb, the only problem with not running a large enough return to the tank is pressure creep and not being able to lower pressure low enough. If it is already there try it if you can't get the pressure down, then you will need a larger return.

 

actually that is the fuel system i was thinking about, minus the -6 lines, before i started reading about return lines, motor is still on the stand and i havent started any of the plumbing yet. the setup is, 347, afr 205cc heads 1.6 rr, vic. JR intake, CSU 750 carb. comp cams XE274HR. hooker super comp headers. the pump is fuel lab 41403 it's good to 1800 horse i got a good deal on it. buddy gave me what i think is a holley blue non return reg but if i'm going to need a return line i guess i'll get a aeromotive one for sure unless there is a good alternative someone would recommend.

 

1800hp capable fuel pump will need a lot of return. -8an won't cut it, -10 might not. A pump that moves that much fuel needs a BIG return, especially on a blow through. Too small of a return will not allow you to get FP low enough.

Are you talking about 1 -6an to the carb or 2? 2 -6an would work a single, no.

 

yeah i think i'm going to go ahead and run a single -8. yeah i went with the fuel lab pump becuse it has an internal speed control, is that going to be a good enough system to be able to dial it in and run the -8 return line? wouldnt be opposed to running a -10 return but i have 20 feet of -8 already and i would love to just use it? and save the money i dont have.

 

If you already have the line, mock it up off the car and see if you can get the pressure correct.

 

In a carb setup, I would do -8 return

 

For a carb the return line should be at least as large as the feed line.

 

What does the pump use to regulate output? If it is boost you should be OK. If it is rpm it may flood the carb if rpm is up and no boost.

 

I googled them but could not find much. Looks like they flow 200 GPH at 20 PSI....not sure about at 7 PSI. If it is just over 200 GPH you can probably get away with a -8 but it will be close. Like others have said, mock it up and see how it goes. You want to be able to regulate the pressure down to 3-4PSI. If you can do that then you are good to go. If not you need a larger return.

 

Thanks to all for the help pump should be here friday and i will be mocking it up by the weekend i think. i'm not going to be running boost till next summer i dont think, going to build a new bottom end not a stock block, and use my current top end. have a BG-280 new in the box if anybody needs one, couldnt use it when i changed plans to a street car. Thanks again to all who chimed in

 

just to be clear you can't use a non return style regulator as a return style one? say it has one -10 inlet and 2 -8 outlets you cant run one to the carb and use the other as a return line?

 

It will not have much pressure since the return line will bleed off all but what resistance there is in the return line.

 

maybe i'm reading that wrong maybe i'm just dumb to regulators. can you give me a little more detail on that and maybe a part number of a good regulator? i was asking about the non return style because someone just posted a magnafuel reg in the classifieds and it's a non return so if it could work i would go ahead and purchase it.

 

A non return, or dead head, regulator has the pressure control between the inlet and outlet. All the outlets are connected to if you connect one to the carb and one to the return, the fuel will return to the tank and leave no pressure to the carb. A return regulator has the inlet and outlets all connected to a common chamber. At the bottom of the chamber is a relief valve that leads to the return port. Once the chamber has desired pressure it bleed off any extra fuel to the tank. If the regulator has too small of an orifice it will not be able to bypass enough fuel to keep pressure down. The same goes for the size of the return line. A high flowing pump need a high flowing return to be able to get the pressure low enough for a carb. You would be better off with a return reg and only spend the money on a reg and fittings once. An A2000, part# 13202, reg would be a good match for your pump. I hope I understood the question.

 

Yes sir that was exactly what i was asking thank you.

 

The fuel lab web site is the best I have seen for fuel pumps. Google "Prodigy fuel pumps". They give you a ton of technical detail and I believe I read "no dead head regulators" there. MagnaFuel can use a dead head because they have the bypass at their pump.

Fuel lab also sells regulators so I would call them and ask for their recomendation.