Flares or Compression Fittings

[cv2065]

Hey guys. I've probably read more about this than I need to, but lots of conflicting info out there. I'm planning on running 3/8" fuel line, which will consist of -6AN stainless flex line from my tank to a steel or Nicopp hardline underneath the car, then another stainless flex line to the carb. Question is flares or compression fittings? I don't have a flaring tool and seems that the fittings would be much easier. Summit has some AN to tube adaptor fittings (SUM-2200077B).

As a side note, I looked at the nylon flex lines as well. Would be great to run just one line front to back, but have noted that some are smelling fuel and can be compared to a soaker hose?

Thought I'd bring this back up and get some current opinions. Thanks.

[Hankl]

Go with the flare just like you'll have to do on your brake lines.

There might even be a FFR builder in the area with a 37 degree flaring tool set, so you won't need an adapter.

Hankl

[Papa]

If you do hard lines, use 37 degree flare for fuel and 45 degree flare for brakes.

[mikeinatlanta]

Compression is great for your fridge ice maker line and even ok for plumbing under your sink.

[dncharo]

We followed Edwardb's lead and used the Ham-Let Stainless 316 Let-Lok compression fittings to go from our 3/8" Nicopp hard line to -6AN.
https://www.amazon.com/gp/product/B0085F5OYO/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1
He used them for stainless hard lines but I'm assuming they will work just fine with Nicopp ones as well. They were super easy to install and are rated for very high pressures.

[rich grsc]

Compression fitting work great on fuel line.

[cv2065]

Perfect. Thanks for the clarification and feedback!

[mikeinatlanta]

We followed Edwardb's lead and used the Ham-Let Stainless 316 Let-Lok compression fittings to go from our 3/8" Nicopp hard line to -6AN.
https://www.amazon.com/gp/product/B0085F5OYO/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1
He used them for stainless hard lines but I'm assuming they will work just fine with Nicopp ones as well. They were super easy to install and are rated for very high pressures.

Those are in a different league. I was referring to the stuff at HD. When you get right down to it, the Aeroquip fittings I use on steel braided teflon brake lines are technically compression.

[Dave Howard]

If you don't have a flaring tool or don't feel comfortable with your tube flaring skills, the compression to AN fitting is a very easy option. There are loads of manufactures and this SS type of fitting is common practice in industry for various gaseous applications. Therefore, using on the fuel system will work fine.

[NAZ]

You can't go wrong with AN flares and they are less expensive than other options and can be reused. As other have pointed out, quality brand compression fittings made specifically for hydraulic service would work but are not foolproof -- they can easily be installed incorrectly and fail at the most inopportune time.

[mikeinatlanta]

37 degree flares are easy in any tube with the right flaring tool. This is the one for 37 degree single flares. The best I have seen and not too expensive.
86639

[cv2065]

One other question guys. I'll be running a carb'd engine (No FI). Since I'll be using 3/8" pipe and connecting with the -6AN flex lines at both ends, is there a better suited fuel tank pickup than what comes with the kit that has the same -6AN connectors?

[Papa]

One other question guys. I'll be running a carb'd engine (No FI). Since I'll be using 3/8" pipe and connecting with the -6AN flex lines at both ends, is there a better suited fuel tank pickup than what comes with the kit that has the same -6AN connectors?

With the quick disconnect on the fuel pickup, you can use these: https://www.summitracing.com/parts/rus-644120

There are many similar to choose from and this is what Gordon Levy used on the supply and return lines on my fuel pump setup. You can just see them in this picture:

https://thefactoryfiveforum.com/attachment.php?attachmentid=84613&d=1524423650

Edit:

Here's a better picture:

https://thefactoryfiveforum.com/attachment.php?attachmentid=86640&d=1528076649

[cv2065]

37 degree flares are easy in any tube with the right flaring tool. This is the one for 37 degree single flares. The best I have seen and not too expensive.
86639

Thanks Mike. I saw Rigid had one that looked similar for a little over $100. Flaring is not out of the question. Might even find someone local that can let me borrow the tool for a bit, but those fittings look pretty easy.

[cv2065]

With the quick disconnect on the fuel pickup, you can use these: https://www.summitracing.com/parts/rus-644120

There are many similar to choose from and this is what Gordon Levy used on the supply and return lines on my fuel pump setup. You can just see them in this picture:

https://thefactoryfiveforum.com/attachment.php?attachmentid=84613&d=1524423650

Edit:

Here's a better picture:

https://thefactoryfiveforum.com/attachment.php?attachmentid=86640&d=1528076649

Thanks for the info and pic Papa. Helps out a lot!

[Boydster]

One other question guys. I'll be running a carb'd engine (No FI). Since I'll be using 3/8" pipe and connecting with the -6AN flex lines at both ends, is there a better suited fuel tank pickup than what comes with the kit that has the same -6AN connectors?

You could use this one thats setup for FI, just cap the return side (if you're not using return with your carb...) and use an appropriate in-tank pump for your carb.

http://www.promracing.com/fuel-supply/individual-fuel-parts/high-flow-fuel-pump-hanger-for-1986-1997-mustangs.html

[cv2065]

You could use this one thats setup for FI, just cap the return side (if you're not using return with your carb...) and use an appropriate in-tank pump for your carb.

http://www.promracing.com/fuel-supply/individual-fuel-parts/high-flow-fuel-pump-hanger-for-1986-1997-mustangs.html

Thanks Boyd. Great looking setup! I had not 'planned' on using a return with the carb, but any advantages to using a return line or in-tank pump versus the typical mechanical pump on the block?

[mike223]

just cap the return side (if you're not using return with your carb...) and use an appropriate in-tank pump for your carb.



If you're using an EFI in-tank pump for a carb - you will have to use a bypass type regulator and return the bypassed fuel to the return line.

Or you will deadhead the pump and kill it.


There are probably special (appropriate) low pressure in tank pumps available - but running the OEM EFI pump with a bypass regulator seems to be most commonly used in tank system (or I've missed something).

[Boydster]

Thanks Boyd. Great looking setup! I had not 'planned' on using a return with the carb, but any advantages to using a return line or in-tank pump versus the typical mechanical pump on the block?

There are advantages to a return style fuel system, even if you're using a carb. Some things to think about.

The regulator you use determines if you'll use a return or not. Some are made for no return, others mandate a return.

A return keeps the unused fuel circulating and helps to keep it cool. This can help virtually eliminate vapor locking issues. Vapor lock is more common with carbs because of the lower fuel pressures and usually no circulation / return.

An in tank pump is pushing all the time. Its bottom end is submerged in fuel, so all it takes is a little voltage and the fuel is on its way. An inline electric pump uses suction to pull fuel from the bottom of the tank, up through the top and then to the pump. The exception to this is a tank with a sump section installed... usually the external pump is mounted and plumbed very close to the sump, so no real advantage there. But our Fox body tanks are not setup that way. A mechanical pump mounted on the engine and driven by the cam... whew. For a modern performance engine, I wouldnt consider this an option. The entire fuel system from tank to pump is suction and operates on a diaphragm that operates maybe 3/8 to 1/2" each stroke. Quite susceptible to vapor locking issues not only in the lines, but also at the carb. Carb boiling issues require cranking to pump fuel to clear the vapor.

Another thought is filters. In tank pump has a sock filter on its inlet, and virtually never needs removal and cleaning unless there's been an outside problem. The only filter needed is after the pump, generally right outside the tank. An inline pump needs both a pre-filter and a post-filter... one before to protect the pump from tank debris, and one after to protect the engine from possible pump debris. Both need to be checked and cleaned at regular intervals. Mechanical pumps wont usually be damaged or hindered by tank debris, so there's usually only one filter going into the carb. There's also the fact that mechanical pumps are not very good at suctioning through a filter, especially todays tight metal screens. I'm pretty sure most mechanical pumps will dictate no pre-filter.

The pump manufacturer will specify the micron required of each filter required.

Virtually any FI system will require a return. There may be the very odd-ball system out there that does not.

When I was designing my car, I had both a carb and a FI setup designed. Both used in-tank pumps, associated regulators, single filters and return lines.

One more thing... if you're going to use a carb with an in-tank pump, make dead sure you're getting a pump for the pressure required for your carb. Running an FI pump on a carb even with a return style fuel system is just too much. You'll maybe need a 10psi pump on a return system... not a 55psi pump.

[mike223]

The regulator you use determines if you'll use a return or not. Some are made for no return, others mandate a return.



Agreed - But you have to use a bypass type regulator with an EFI pump or it will not live for 3 hours.

Either that or you have to use an electronic pressure controller to run the pump (I think the Coyote control pack does this - pulse width modulation)- if you deadhead an EFI pump it will die, usually in less than an hour of run time.





One more thing... if you're going to use a carb with an in-tank pump, make dead sure you're getting a pump for the pressure required for your carb. Running an FI pump on a carb even with a return style fuel system is just too much. You'll maybe need a 10psi pump on a return system... not a 55psi pump'



Many of us have been running EFI intank fuel pumps with carbs for years with no problems whatsoever (7 years here - thousands of miles - works "perfect").

You need a bypass regulator that can be set to provide ~5 psi, such as: https://www.summitracing.com/search/part-type/fuel-pressure-regulators/regulator-style/return/regulator-usage/carburetor (www.summitracing.com/search/part-type/fuel-pressure-regulators/regulator-style/return/regulator-usage/carburetor)

Here's a brief article, it is very common: http://www.tanksinc.com/index.cfm/page/ptype=results/category_id=163/mode=cat/cat163.htm

[cv2065]

Great info guys. What I'm thinking is that even if I don't go FI right now, I might want to some time down the road, so setting up the plumbing now would make it that much easier.

[edwardb]

Either that or you have to use an electronic pressure controller to run the pump (I think the Coyote control pack does this - pulse width modulation)- if you deadhead an EFI pump it will die, usually in less than an hour of run time.

The DD version of the Coyote works this way. Returnless fuel system with a PCM controlled pump. The crate motor controls pack PCM though is calibrated as a return system with an in-line regulator and the fuel pump running full pressure all the time.


Great info guys. What I'm thinking is that even if I don't go FI right now, I might want to some time down the road, so setting up the plumbing now would make it that much easier.

Pretty simple to future proof your build. Install a return line along with the required supply line. You wouldn't need it for a simple mechanical fuel pump/carb setup. But if/when you go to FI, change out the manual pickup with an in-tank pump. The RF harness has the required electrical connection. Add the regulator using the return line you previously installed, and you're good to go.

[cv2065]

Pretty simple to future proof your build. Install a return line along with the required supply line. You wouldn't need it for a simple mechanical fuel pump/carb setup. But if/when you go to FI, change out the manual pickup with an in-tank pump. The RF harness has the required electrical connection. Add the regulator using the return line you previously installed, and you're good to go.

Sounds like a plan. Thanks Paul.

[Boydster]

Many of us have been running EFI intank fuel pumps with carbs for years with no problems whatsoever (7 years here - thousands of miles - works "perfect").

You need a bypass regulator that can be set to provide ~5 psi, such as: https://www.summitracing.com/search/part-type/fuel-pressure-regulators/regulator-style/return/regulator-usage/carburetor (www.summitracing.com/search/part-type/fuel-pressure-regulators/regulator-style/return/regulator-usage/carburetor)

Here's a brief article, it is very common: http://www.tanksinc.com/index.cfm/page/ptype=results/category_id=163/mode=cat/cat163.htm

Cool. So in addition to the methods I posted, here's another one thats perfectly viable. I just would not have thought to use a relatively high pressure pump and regulate it down to 5psi... but this shows that it will work!

And of course the Coyote engine makes most of what I said just plain flat wrong... EFI, High pressure / flow capable pump and no return. The computer regulates pump volume / pressure... But you're not running a Coyote with a carb, so...

[mikeinatlanta]

And of course the Coyote engine makes most of what I said just plain flat wrong... EFI, High pressure / flow capable pump and no return. The computer regulates pump volume / pressure... But you're not running a Coyote with a carb, so...

Something guys should pay close attention to before making a FAS. Technology has shifted and the latest and best systems are now going returnless. times are a changing.

[mike223]

I just would not have thought to use a relatively high pressure pump and regulate it down to 5psi... but this shows that it will work!




Just to be clear for anyone who is following along...

I'm not sure I would call it regulating down to 5psi - but effectively that's what you're accomplishing.

What you're really doing is pumping all the fuel you can pump and sending anything beyond what is required to maintain 5psi back to the sump (baffle).

Continually overfilling the baffle is helpful.


But you can't undersize the return line / fittings (or you can't get it down to 5psi).