Fuel System Choice
 

Hey guys I am on the fuel system stage of my restoration and really need some help on a fuel system for the car.

My Set UP 455 bored .040 with 4.5 stroke. Dynoed 560 HP and 650 Ft. Pounds of torque

It has a 950 cfm carb running to a fuel cell in the back. This will be running an 8 an line to the carb and 6an return line back to the fuel call. I have purchased a 35 micron and 100 micron fuel filters with 8an inlets and outlets.

I am having difficulty finding the right size regulator and pump for the car. I thought a Holley Blue fuel pump but they only come with 6an inlets and outlets and the same story for the regulators. Also what pressure do I set this regulator at when I am done. Any advice on the regulator and pump selection would be appreciated? Brands that have worked for your combo? Advice on the fittings, going from 6an to 8an or not?

Thanks
Chris

Probably not what you want to hear but I had trouble with mine making similar power all the way up until I went Tanks Inc with an in tank pump.

It’s not just the pump, but the better tank with baffles.

Ouch yeah can see the fuel taking some ggggg’ss and moving to the back of the tank. May have to make sure the tank stays at least half full to avoid that issue hopefully cause i dont have foam in it

Agree, I’d want some sort of sump in this system. I’d use a walbro 255 in a tanks Inc tank with a bypass regulator.

I would run a regulator like this. https://www.speedwaymotors.com/Aerom...SAAEgK9MvD_BwE

You could actually run this in a “corvette” setup with the regulator in the rear with a short return line and the supply to the carb in a dead head style.

Mallory 140 with a return regulator and run 8an supply and return lines.

Please note that the Holley blue regulator is a bad restriction in terms of being used with a 4 bbl carb!

The control flow needle used in it has far less flow area then both float bowl needle and seats combined in even a small Holley 600 cfm carb, just bad news!

To me the only acceptable place to use one is on a dirt track 2bbl carb limited motor.

Thanks for the recommendations. I see these pumps mostly have 6an ports. i assume i will need a 8an to 6an fitting? Will this impede fuel flow?

I ran an Auromotive A750 on my wife's 68 Firebird with -6 lines to the reg and back to the tank. We ran a best of 10.83 with that setup. Tank was sumped with a -10 feeding inlet side of 100 micron filter. 10 micron at carb. -8 from reg to carb. Engine was around 600 hp 600 torque. 950 quickfuel carb.

You want 10 micro at carb, not 35. Fuel pressure set at 6.5 to 7 psi. I run 6.5 psi. Follow the manufacture recommendation for line sizes. If you put a -8 on a pump that requires a -6 supply, you will be loading the pump up current wise. It puts too much head pressure on the pump supply making it work harder, and can cause fuel delivery issues. I used a teflon liner braided hose good for fuel.
Aermotive shows diagrams on how to properly install a fuel system.

https://aeromotiveinc.com/product/a750-fuel-pump-2/

So again, direct experience with this.

Initially with my 462 a Q jet and a Robb MC 600 pump, I couldnt get down the track at all. Would fall on its face at like 100-300 feet. This is with 1/2" lines and a 1/2" pickup.

Upgraded to Robbs bigger pump, a regulator and vent line. That worked until you didnt have the tank mostly full. If you were below like 2/3rds it would run away from the pickup and fall on its face.

Got tired of the nonsense, I found a Tanks Inc LS swap setup for sale used locally and installed that. No more problems. Was still able to use Robbs regulator. Really nice piece. Highly recommend that. reasonably priced too.

Then I installed a Holley Terminator and now I have new problems. Because Hot Rods.

I will say with yours you have 2 needle and seats where I only had one. That MIGHT mask some issues and let you get away with it. If you want to find fuel system deficiencies install a QuadraJet.

You mention a fuel cell. If it has a gravity fed sump, then you're just looking for and inline pump mounted lower than the cell that flows enough fuel for the power level. There are formulas out there for determining this. Basically it takes .5 lb/HR per horsepower. Build a little extra in for gravitational forces. And the flow rating needs to be correct at the pressure you intend to run. Wide open ratings aren't the whole story. As pressure goes up volume goes down. The 140gph pump mentioned earlier is a pretty well vetted number for your power level. Aeromotive makes a return regulator that many here use at carb pressures and comes with a spring to swap it to efi pressure if the need ever arises.
All that being said, the efi style in tank pumps are nice, and offer some advantage, at a cost of course.

i am considering the corvette style regulator with tanks inc set up but am curious of the psi of those regulators, arent they set up for FI at high psi? for carb use you need a reg with much lower psi... do you know if they make vette style regulator to use with carbs? or can a standard carb psi bypass reg be used back near the tank for a easier & shorter return line?

Caddor, is this a race car or street/strip? I am at a similar power level and am using a Tanks, Inc (baffled tank, small sump, corners cut off the front), 340 lph pump, 8AN feed AND return, Weldon regulator, feeding an 850 QF Holley. I could have saved a LOT of $$$$ and time if I did this from the beginning. The Holley Blue or Black pumps should work great with your fuel cell. I had the latter for a short time and it was too loud for me personally on the street. I would definitely use the same size return and feed line. PSI should be dictated by the carb manufacturer, 6.5 in my case. Whatever you do, put a fuel guage inside the car(even if it's temporary) to make sure you have constant pressure. I am far from an expert but this worked for me. Good luck!

These pumps, holley blue, hp150, mallory etc do not have AN ports. They mostly have 3/8 NPT pipe thread ports, i never could figure out NPT nomenclature but 3/8 NPT is bigger than 1/2" and can easily accommodate a - 8AN fitting. Just install 3/8NPT to - 8AN fittings and run - 8An lines and there will be no restriction
Jon

Oh man thanks! Now I understand, thank goodness you posted that so 3/8 npt to 8an fittings. I am assuming that most pumps will not come with thes fittings in the box but thats okay, im assuming it will be 3/8 not to 6-an

Think you will find that with a true return regulator that you should use at least -8AN return. On my drag car even the -8AN return line created a 6.5 PSI back pressure. Going to a -10AN line lower that to 2 PSI. Anyway, if you do use the -6AN return line, don't be too quick to blame the regulator if you can't get the pressure down with the adjustment screw.

Wow, okay i will use the 8an return. thanks

AN = Army Navy fitting. they are based on a 37* flange UNLIKE common SAE flare fittings @ 45* Sizes are a easy as it gets....take the size number put it on TOP of 16. EAXAMPLE: 8AN = 8/16" or....1/2" So a 6AN would be 3/8". This is the O.D. of the tubing

Another vote for Mallory. I ran a 110 converted to bypass with a Mallory bypass regulator. Ran 1/2" supply and return. Rock steady fuel pressure all of the time. Ran Holley Blue pumps back in the day. They were LOUD and unreliable. Holley Blue is a rotary vane pump. Mallory is a gear rotor. Gear rotor is much quieter and more efficient.

yeah thats two votes for the mallory. I will give the mallory 140 a try and probably get there matching regulator with bypass. Thanks for the help. It may be a while but I will fillow up.

I have a perfectly good Mallory 110 and bypass regulator if you're interested. I'm switching to LS. Doubt I'll need these, maybe ever. PM me if ya want. I'll try to figure out a good deal price for them. I actually have a backup Mallory 110 also. Both with very little run time.