View Full Version : Swapping from braided to hard fuel lines -- what fittings work best?
Hi all:
As I begin laying out my fuel system upgrade, I've decided to start at the tank and replace pretty much the entire system all the way through the EFI. That said, I'm going to start with replacing the braided -6 lines with 3/8" hard lines. I'm considering using NiCop tubing because of the ease of forming and flaring it. If someone thinks that's a really bad idea, please chime in before I start buying parts. Also, what type of fittings are best to use on the hard line that get me to -6AN standard? I'm seeing a bunch of compression fittings and that just doesn't seem like a good direction considering the pressures that will be involved with the fuel system. I'm thinking more of a nut that goes on the line before a 37 degree flare with male threads. What do the experts recommend?
Dave
txboiler
12-03-2021, 03:01 PM
I am interested to hear the responses as well. I used nicop lines with AN flare and nuts. The only place I had to use compression fittings was for the braided lines in the engine bay going from hardlines to sniper.
rich grsc
12-03-2021, 04:15 PM
Compression fittings will hold WAY MORE pressure than you'll ever see on a fuel system.
Rockman
12-03-2021, 04:16 PM
I used NiCopp hard fuel and return lines and I am pleased with the results. In addition, I used nuts, sleeves and I also used in a few places:
Russell Performance 660353 - Russell ProClassic Couplers – Fitting, Coupler, Union, AN to AN, Straight, Aluminum, Black Anodized, -6 AN, -6 AN, Each.
The clamps from Lodestone BilletWorks are a nice touch.
I had flexible fuel lines fabricated to go from the NiCopp fuel lines to the Sniper in the engine compartment by Aircraft Specialty http://www.aircraftspecialty.com/ They make very nice custom hoses.
Finally, I found this article helpful on how to properly tighten AN fittings (counting flats method) on the Pegasus Auto website:
https://www.pegasusautoracing.com/document.asp?DocID=TECH00157
Hoooper
12-03-2021, 04:54 PM
AN tube adapter fittings, something like this https://www.summitracing.com/parts/FRA-892006BL. More than plenty of pressure holding capacity for port fuel injection systems
edwardb
12-03-2021, 05:08 PM
I'm a huge fan of the Ham-Let Stainless Steel 316 Let-Lok Compression Fitting, Adapter, 3/8" Tube OD x 37 Degree Flare. Breeze has them. Pretty sure Forte sells them. They're on Amazon. Go directly from the hard line to a male -6AN connection. No adapters or flare required. NiCopp is fine if that's what you want. Steel or SS works too. Easy because you don't need to do flares. Just have a decent bending tool. They're rated way beyond anything in our EFI systems. You won't find anything better IMO. I've used them on all my builds.
As usual, this community has the answers! Thanks for the quick and helpful responses. Looks like NiCop and compression fittings it is! I'll definitely look at the Lodestone clamps. I recall looking at their stuff while I was building the car and liked what I saw.
Dave
P.S. - Considering this pressure regulator setup: https://www.amazon.com/dp/B07JNXSF9V/?coliid=I36ITL9EF8YDAN&colid=TU1R4N1KFE6A&psc=1&ref_=lv_ov_lig_dp_it
Still haven't settled on the intake and specific EFI, but leaning Holley Terminator for MPFI.
I'm a huge fan of the Ham-Let Stainless Steel 316 Let-Lok Compression Fitting, Adapter, 3/8" Tube OD x 37 Degree Flare. Breeze has them. Pretty sure Forte sells them. They're on Amazon. Go directly from the hard line to a male -6AN connection. No adapters or flare required. NiCopp is fine if that's what you want. Steel or SS works too. Easy because you don't need to do flares. Just have a decent bending tool. They're rated way beyond anything in our EFI systems. You won't find anything better IMO. I've used them on all my builds.
Paul,
Those fittings look really high-end. Did you use rolled tubing for your lines? I see rolls od SS tubing that are seam welded. Any issues with that fabrication method?
Dave
edwardb
12-03-2021, 05:36 PM
Paul,
Those fittings look really high-end. Did you use rolled tubing for your lines? I see rolls od SS tubing that are seam welded. Any issues with that fabrication method?
Dave
To be honest, I'm not positive of the construction method of the SS tubing I've used and don't know anything about different methods. I get it from https://www.inlinetube.com/ and it's intended for automotive applications. So however it's made hasn't been an issue for me. Most of their sales are on-line. But they're local for me so I've been able to do counter sales and get straight lengths. Which was really nice. Whatever they ship is coiled. Like everyone else. But can be staightened.
Namrups
12-03-2021, 05:52 PM
Paul, can the SS coiled tube be straightened by hand or do you need the tube straightener?
Paul, can the SS coiled tube be straightened by hand or do you need the tube straightener?
These work really well. I used one for my 3/16 brake lines. A little pricy but make quick work of the task.
https://www.amazon.com/gp/product/B07PPJ1NFX/ref=crt_ewc_title_dp_1?ie=UTF8&psc=1&smid=AS9TMMX2PSD5N
edwardb
12-03-2021, 06:04 PM
Paul, can the SS coiled tube be straightened by hand or do you need the tube straightener?
Depends on how picky you are and how long the length is you're trying to straighten. I've been able to get straight SS pieces, as I mentioned in an earlier post. So I haven't had to try. I did end up using steel brake lines in my truck build and used a coiled length from Summit. InLine tube wasn't doing counter sales at the time due to Covid. I was able to straighten it quite acceptably by hand and no special tools. But if it were SS, I probably would have bought one of the straightening tools. I know that's not much of an answer. But all I've got.
OVCobra
12-03-2021, 06:06 PM
As rich grsc noted, compression fitting will hold over 1,000 psi so EFI fuel pressure is not a problem. I used Swagelok fittings and 316 SS seamless tubing...its a little pricy but worth it knowing there will be no leaks or corrosion issues. It also polishes up easily if you are so inclined. No fuss trying to flare the SS (which rapidly work hardens) and ran hard line right to the pressure regulator which was mounted on the firewall. Used a male npt x AN fitting to run braided line across to the engine.
No leaks or issues in 7 years.
As usual, this community has the answers! Thanks for the quick and helpful responses. Looks like NiCop and compression fittings it is! I'll definitely look at the Lodestone clamps. I recall looking at their stuff while I was building the car and liked what I saw.
Dave
P.S. - Considering this pressure regulator setup: https://www.amazon.com/dp/B07JNXSF9V/?coliid=I36ITL9EF8YDAN&colid=TU1R4N1KFE6A&psc=1&ref_=lv_ov_lig_dp_it
Still haven't settled on the intake and specific EFI, but leaning Holley Terminator for MPFI.
Dave, I am running that same Aeromotive pressure regulator and after 2100 miles it has been excellent. I am a fan of Aeromotive also using there fuel filter and in tank pump. For your EFI system might be worth looking at the Edelbrock PF4 if you want true MPFI. Especially if you are going to purchasing a new intake, the PF4 comes with intake, TBI, distributor and tablet. After 2100 miles the PF4 has been treating me well. Just something to consider, good luck with your upgrade and whatever you choose hope it works out well for you.
As usual, this community has the answers! Thanks for the quick and helpful responses. Looks like NiCop and compression fittings it is! I'll definitely look at the Lodestone clamps. I recall looking at their stuff while I was building the car and liked what I saw.
Dave
P.S. - Considering this pressure regulator setup: https://www.amazon.com/dp/B07JNXSF9V/?coliid=I36ITL9EF8YDAN&colid=TU1R4N1KFE6A&psc=1&ref_=lv_ov_lig_dp_it
Still haven't settled on the intake and specific EFI, but leaning Holley Terminator for MPFI.
Fun fact about the Aeromotive regulator: you should only use Aeromotive connectors. Others will leak. This was pointed out to me by Aeromotive tech support way back when. He was right. Other than that, the Aeromotive setup is top notch!
Fun fact about the Aeromotive regulator: you should only use Aeromotive connectors. Others will leak. This was pointed out to me by Aeromotive tech support way back when. He was right. Other than that, the Aeromotive setup is top notch!
Are you saying that the included ORB to AN fittings will leak with other AN fittings or that the ORB side will leak if not using their provided parts?
Are you saying that the included ORB to AN fittings will leak with other AN fittings or that the ORB side will leak if not using their provided parts?
If you use someone else's ORB/AN fitting, the ORB side will leak. If you use an Aeromotive ORB fitting, everything will be fine. Mine came with "other" fittings and I couldn't figure out why they leaked. The Aeromotive guy asked me to send him a photo and that's when he told me about it. Once I installed the Aeromotive pieces, everything worked as expected. I can't explain why this is the case, but I figured it was worth letting you know.
Papa, there is a safety advantage to using good quality AN braided hose from tank to carb or injection. If you run hard lines adjacent to the flywheel area, NHRA requires them to be in .120" wall steel tubing but SS braided AN hose can be run in the same area without any protective shielding. In a crash, the braided hose is less likely to be damaged to the point of rupture. Most don't think the cost is worth it and use hard lines most of the way. But you're going the opposite direction. Is there an issue with your AN hose?
Also, be advised that AN is a military standard and all true AN compliant fittings are interchangeable. That said, there are many different PTFE SS braided hose that the manufactures loosely call AN that are not built to the AN standard. The fittings on the adapter side are AN but the hose side are proprietary and you can't reliably interchange hose end fittings.
As for the interchangeability of AN fittings on Aeromotive regulators, that's a new one on me. I used an Aeromotive fuel pressure regulator on one of my race cars and installed non-Aeromotive AN adapters on the regulator and a different brand hose ends on the braided AN hose and have no incompatibility issues. This is a turbo EFI system and the regulator is set to 68 PSI and the dual Aeromotive fuel pumps will push fuel to the regulator at much higher than that. No leaks.
Papa, there is a safety advantage to using good quality AN braided hose from tank to carb or injection. If you run hard lines adjacent to the flywheel area, NHRA requires them to be in .120" wall steel tubing but SS braided AN hose can be run in the same area without any protective shielding. In a crash, the braided hose is less likely to be damaged to the point of rupture. Most don't think the cost is worth it and use hard lines most of the way. But you're going the opposite direction. Is there an issue with your AN hose?
Also, be advised that AN is a military standard and all true AN compliant fittings are interchangeable. That said, there are many different PTFE SS braided hose that the manufactures loosely call AN that are not built to the AN standard. The fittings on the adapter side are AN but the hose side are proprietary and you can't reliably interchange hose end fittings.
As for the interchangeability of AN fittings on Aeromotive regulators, that's a new one on me. I used an Aeromotive fuel pressure regulator on one of my race cars and installed non-Aeromotive AN adapters on the regulator and a different brand hose ends on the braided AN hose and have no incompatibility issues. This is a turbo EFI system and the regulator is set to 68 PSI and the dual Aeromotive fuel pumps will push fuel to the regulator at much higher than that. No leaks.
NAZ,
It's been suggested to me that because my braided lines are not PTFE-lined, that they can start to deteriorate with prolonged exposure to ethanol blended fuel. I figured going to hard lines with PTFE braided for the short interconnects was a wise choice. I'm no expert, so I welcome the opportunity to learn.
Dave
mikeinatlanta
12-04-2021, 04:06 PM
As an FYI, AN is referring to the hard line fittings and not the interface to any braided line. All of the hard line fittings are fully interchangeable but the braided line side you should use the same brand for the hose and fitting. Always, always, always perform a high pressure leak check on any hose with a fitting. Everyone is sourcing from China and the tolerances can't be trusted. Had this issue where even Fragola couldn't get their .4 fittings to hold pressure.
Would not use any type of compression fitting on NiCop. It is a soft metal and the fitting will not be durable with any sort of vibration. NiCop is great for the hard line, however, you may run afoul of both sanctioning body and DMV regs as neither are fully up to speed on NiCop. If you want compression on a high end product, I suggest MS fittings. They have been doing great for over 30 years on airplanes.
Regarding welded tubing. This is an issue with almost all of the stainless out of China. They externally polish welded tubing and call it seamless. (this included Summit seamless). Weld tubing is fine for compression, bubble, or double flares, however, for AN flares you must clean up the weld line with a proper finishing tool.
Dave, alcohol blends are a concern when using the rubber hose. The PTFE hoses are tolerant of alcohol but not all are equal. Be sure to use PTFE that is carbon infused so it's conductive. Fluids flowing through non-conductive SS braided hose can build a static charge that arc's from the tubing to the SS outer layer causing pitting in the inner tubing and eventually leaks. You don't see this in brake lines as there is very little flow but a fuel line has enough flow to build a static charge.
Dave, alcohol blends are a concern when using the rubber hose. The PTFE hoses are tolerant of alcohol but not all are equal. Be sure to use PTFE that is carbon infused so it's conductive. Fluids flowing through non-conductive SS braided hose can build a static charge that arc's from the tubing to the SS outer layer causing pitting in the inner tubing and eventually leaks. You don't see this in brake lines as there is very little flow but a fuel line has enough flow to build a static charge.
What product(s) do you recommend?
I've used several manufacturer's PTFE lined SS braided hose and fittings and all worked but the two I tend to like working with are Aeromotive and Earl's. Both use carbon to add conductivity to the liner.
https://www.holley.com/blog/post/how_to_choose_fuel_hose_-_earl_s_plumbing/
I spent some time today looking at the Edelbrock Pro Flow 4 (Edelbrock 35940) and it's definitely an intriguing option. I'm really confused by the various Terminator packages that I'm seeing and not sure how to piece an entire Holley system together but will keep reading. I have a neighbor that swears by them and said he could explain what I need.
CDXXVII
12-05-2021, 12:38 AM
I ran all stainless steel hard lines and used ptfe stainless braided for final connections. The transition fittings on the fuel lines are swagelok compression to AN.
https://thefactoryfiveforum.com/attachment.php?attachmentid=82790
https://thefactoryfiveforum.com/attachment.php?attachmentid=82791
https://thefactoryfiveforum.com/attachment.php?attachmentid=82792
https://thefactoryfiveforum.com/attachment.php?attachmentid=82794
Namrups
12-05-2021, 07:58 AM
What heat shielding did you use in the engine bay?
CDXXVII, you do beautiful work.
burchfieldb
05-01-2022, 12:33 PM
I ran all stainless steel hard lines and used ptfe stainless braided for final connections. The transition fittings on the fuel lines are swagelok compression to AN.
https://thefactoryfiveforum.com/attachment.php?attachmentid=82790
https://thefactoryfiveforum.com/attachment.php?attachmentid=82791
https://thefactoryfiveforum.com/attachment.php?attachmentid=82792
https://thefactoryfiveforum.com/attachment.php?attachmentid=82794
That looks awesome! What size are your fuel lines?
Mike.Bray
05-01-2022, 04:49 PM
Back when I first started building cars try as I might I could never produce a decent double flare. It was probably some the cheap flaring tools I had and some my lack of talent. This caused be to go to stainless tubing with 37 degree flares for AN fittings and never had a leak or a problem. I always liked the looks of hard line too, look how awesome it looks above in post #25. Some things I learned:
37 degree AN flares are single flares and require seamless tubing.
AN flares should be produced with a burnishing flaring tool. Mine is from Imperial Eastman. https://imperial-tools.com/products/400-f-37-rol-air-flaring-tools/
Stainless steel tubing is tough, use good lever benders!
Straightening 3/8" coiled stainless steel tubing separates the men from the boys even with a good quality straightener like this one https://www.eastwood.com/tube-straightener.html To me it's worth the extra cost to buy straight lengths.
Use good quality fittings like Earl's. I found Russell's to be so-so quality compared to Earl's but maybe they just had a bad day.
Put the sleeve on before flaring.
When you're done step back and be proud.
https://www.imagecoast.com/images/MichaelBray1/dscn0604small.jpg
burchfieldb
07-01-2022, 09:24 AM
I wanted to see what you guys thought about conductive vs non-conductive PTFE fuel lines? I searched the forum, but came up empty. Trying to figure out what I want to use between my hard lines and the engine.
richtersand
07-01-2022, 03:28 PM
Hi all:
As I begin laying out my fuel system upgrade, I've decided to start at the tank and replace pretty much the entire system all the way through the EFI. That said, I'm going to start with replacing the braided -6 lines with 3/8" hard lines. I'm considering using NiCop tubing because of the ease of forming and flaring it. If someone thinks that's a really bad idea, please chime in before I start buying parts. Also, what type of fittings are best to use on the hard line that get me to -6AN standard? I'm seeing a bunch of compression fittings and that just doesn't seem like a good direction considering the pressures that will be involved with the fuel system. I'm thinking more of a nut that goes on the line before a 37 degree flare with male threads. What do the experts recommend?
Dave
Funny, I used nicop fuel lines (and brake lines) thanks to YOUR endorsement of the material on your build thread :)
So far so good but I only have 300 miles on the car! Running 65PSI through the coyote gen3
I wanted to see what you guys thought about conductive vs non-conductive PTFE fuel lines? I searched the forum, but came up empty. Trying to figure out what I want to use between my hard lines and the engine.
There is a lot of information about this topic available on the Internet. In general, the use of conductive PTFE hose is recommended over non-conductive based on the potential of building up static discharge in non-conductive PTFE (Teflon) lined hose. The concern is that if enough buildup occurs, it can spark/arc and cause pitting in the hose or even ignition of the fuel (worst case). For my original lines, they were not PTFE lined. My new lines are a combination of NiCop hard lines and Aeromotive conductive PTFE flex.
Funny, I used nicop fuel lines (and brake lines) thanks to YOUR endorsement of the material on your build thread :)
So far so good but I only have 300 miles on the car! Running 65PSI through the coyote gen3
I ended up using HAM-LET fittings vs. faired fittings on the NiCop on my car. They work great and are rated at something like 1000psi.