Stainless Fuel Lines

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Stainless Fuel Lines

Postby egrant5329 » Thu Jul 13, 2017 6:12 am

What's the current opinion on stainless steel hard fuel lines on dual carbs like what Airkewld sells? It seems like it should be safe, but with the engine expanding and contacting I don't want to have any concerns about cracking/leaking/safety. The rubber lines I currently have work, but the hard lines would make for a cleaner look.
Thoughts or opinions?
Thanks,
Ed
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Re: Stainless Fuel Lines

Postby danstern » Thu Jul 13, 2017 6:48 am

I'm not particularly knowledgable about this, but it would seem that you need a short length of rubber to handle vibration and movement. Without it I don't see how the motion could be prevented from forming stress cracks.
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Re: Stainless Fuel Lines

Postby sjgharib » Mon Jul 24, 2017 11:41 am

I echo that - unless you have rigid transaxle mounts (which would not be good), your engine / transaxle will move around at least as much as the mounts will flex.
Thus depending on where you are with relation to the mounts, you could have pretty significant movement. You need something flexible to bridge that gap.
I have hard lines to a point on the firewall, then transition to flexible -AN hose to make the jump to the engine.
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Re: Stainless Fuel Lines

Postby DannyP » Mon Jul 31, 2017 11:08 am

Agreed. Rubber line from tank to filter, and filter to pump, then pump to tunnel. In tunnel is steel 3/8" line to a T in back, then steel lines up firewall to a filter on each side. Then rubber lines to each carb.

As an aside, I use the spring clamps on the carb and fuel filter. I'm not a fan of the worm drive clamps, they can cut the hose and be overtightened.
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Re: Stainless Fuel Lines

Postby egrant5329 » Mon Jul 31, 2017 2:46 pm

Thanks. I currently run rubber from the tank to the fuel pump and filter (both are in the front compartment. Then I run braided stainless back to the driverside carb and use rubber from carb to carb. Does anyone run a fuel pressure gauge? Is it just plumbed to one of the carbs?
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Re: Stainless Fuel Lines

Postby RVosari » Tue Aug 01, 2017 12:45 am

With your fuel supply set-up... a gauge before the carbs or between the carbs, would show the same (accuracy of) pressure.

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Re: Stainless Fuel Lines

Postby DannyP » Wed Aug 02, 2017 7:13 am

I'd check the pressure and have a gauge to throw in if you have a problem. Not really a need to constantly monitor. Besides, you won't be able to read the gauge under load.

My friend Max's engine builder installed a gauge right on the passenger side Weber, in the double-sided fuel inlet. The gauge failed and gave us false low readings, probably from constant vibration.
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Re: Stainless Fuel Lines

Postby Jammer » Sun May 27, 2018 1:43 am

I'd be concerned about potential static buildup using stainless steel for fuel lines. Instead, I'd consider PTFE or steel braided PTFE hose if abrasion is an issue.
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Re: Stainless Fuel Lines

Postby RS-60 mark » Sun May 27, 2018 9:08 pm

Similar to that mentioned above, I have a short section of rubber hose from the output of the fuel pump that connects to stainless tube running the length of the cockpit and into the engine bay. From there it is connected to rubber hose sections to another filter and then fuel pressure regulator and then to carb #1 banjo. (The carb #1 banjo provides the "Y" connection for fuel to carb #2). The cross connection between carb #1 banjo and carb #2 banjo is via stainless tube tipped with rubber hose connected to the banjos.
I've never considered the thought of static as an issue. Although the run through the cockpit is grounded, the length between the carbs is not (isolated by the rubber hose on each end). I have no idea how much (if any) static potential can be generated by the volume and velocity of gasoline flow through the stainless tube.

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Re: Stainless Fuel Lines

Postby dlearl476 » Tue May 29, 2018 1:38 am

DannyP wrote:
As an aside, I use the spring clamps on the carb and fuel filter. I'm not a fan of the worm drive clamps, they can cut the hose and be overtightened.



I bought boxes of these from Wurth for another project. I just de-rusted my tank, replaced all the hardened rubber lines, and all the cheapo hose clamps with these. 6mm braided fuel line takes either a 12mm or 13mm clamp depending on what size barb it goes over. IIRC, the two banjo fittings on my Dellortos took 14mm clamps.

The only thing I don't like about them is the require a straight-blade screwdriver. I wish I could find some with the 7mm hex.

For those of you who don't already have a lifetime supply of the other kind :(
https://www.caphardwaresupply.com/produ ... nless-10pk

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Re: Stainless Fuel Lines

Postby albaran » Tue May 29, 2018 7:09 am

I have a fuel pressure gauge on the firewall attached to a fuel block that separates the two lines that run to the carbs.
It came in real handy this weekend when my car suddenly died. I opened the hood and could see that the fuel pressure was zero because a wire on the fuel pump had come loose. I popped it back on and went on my way.
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Re: Stainless Fuel Lines

Postby dlearl476 » Tue May 29, 2018 11:50 am

I recently bought a Malpassi Filter King fuel filter/regulator for my Beck. I opted out of the model with the gauge because a) the literature said to remove the gauge after the pressure is set and b) I found one without the gauge fir about half price. (At aircooled.net)
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Re: Stainless Fuel Lines

Postby EEricson » Tue May 29, 2018 5:09 pm

I love those things. They look a lot like what original Spyders had.
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Re: Stainless Fuel Lines

Postby RS-60 mark » Wed May 30, 2018 8:37 am

I also recommend the Malpassi regulator (from aircooled.net).
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Re: Stainless Fuel Lines

Postby dlearl476 » Wed May 30, 2018 12:14 pm

RS-60 mark wrote:I also recommend the Malpassi regulator (from aircooled.net).

Mark, where did you mount your filter/regulator? I've been scouting all over the engine bay for a location away from the exhaust. Leaning towards mounting a L bracket between my roll bar tubes. Want to keep it inside the frame rails in case of an accident, but real estate is at a premium.

I'm also going to have to swap my single/ double banjos around and re-route the fuel line, but I think it will be better in the long run. Apparently I waited too long and single banjos for the small bolt are NLA, and I'm tired of worrying about the plug I have on my double banjo.
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