fuel line - HARD or FLEX ?
Thread Starter
TECH Enthusiast
Joined: Apr 2006
Posts: 630
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From: New York City
fuel line - HARD or FLEX ? I know this has been discussed before and I searched a while with no results.
I'm at the point of doing the fuel system on my chevelle and was planning on going flex from the filter/regulator into hard then back to flex into the fuel rail. I would rather go flex all the way -the line would be strapped well and be away from any mechanical or heat areas. what are your thoughts? thanks JOHN
I'm at the point of doing the fuel system on my chevelle and was planning on going flex from the filter/regulator into hard then back to flex into the fuel rail. I would rather go flex all the way -the line would be strapped well and be away from any mechanical or heat areas. what are your thoughts? thanks JOHN
Originally Posted by john 67
I'm at the point of doing the fuel system on my chevelle and was planning on going flex from the filter/regulator into hard then back to flex into the fuel rail.
(I thought of a couple more arguments against it while I was typing that - cost, & weight - the braided line probably weighs slightly more than the hard line.
But, if the hard line doesn't move enough fuel for the power you're making...)I might have to run more than 12" of flex line with my swap, if I do, I guess I'll have to take my chances...
You can do something like this from Summit or Jegs:
http://store.summitracing.com/partde...5&autoview=sku
The aluminum line is easy to shape and flare for routing, then use the flex line on the ends. Just don't kink it, use a proper tubing bender.
Pat
http://store.summitracing.com/partde...5&autoview=sku
The aluminum line is easy to shape and flare for routing, then use the flex line on the ends. Just don't kink it, use a proper tubing bender.
Pat
Does that kit use compression fittings for the hard line or inverted flare? I'm not sure I would trust compression fittings for pressurized fuel.
You can do something like this from Summit or Jegs:
http://store.summitracing.com/partde...5&autoview=sku
The aluminum line is easy to shape and flare for routing, then use the flex line on the ends. Just don't kink it, use a proper tubing bender.
Pat
http://store.summitracing.com/partde...5&autoview=sku
The aluminum line is easy to shape and flare for routing, then use the flex line on the ends. Just don't kink it, use a proper tubing bender.
Pat
Originally Posted by Stu Cool
You can do something like this from Summit or Jegs:
http://store.summitracing.com/partde...5&autoview=sku
The aluminum line is easy to shape and flare for routing, then use the flex line on the ends. Just don't kink it, use a proper tubing bender.
Pat
http://store.summitracing.com/partde...5&autoview=sku
The aluminum line is easy to shape and flare for routing, then use the flex line on the ends. Just don't kink it, use a proper tubing bender.
Pat
(I really don't need another tubing cutter, but for the price of that kit, I'll deal with it...) 
Originally Posted by garys 68
Does that kit use compression fittings for the hard line or inverted flare? I'm not sure I would trust compression fittings for pressurized fuel.
I was thinking of using compression fittings in 2 spots near my tank (to mate the hard output line from the tank to a short length of braided hose), but I don't want an "up close & personal" view of a Car-B-Q... 
Actually, come to think of it, I have at least one compression fitting in use by the filter/regulator... Hmmm.
Thanks.
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The old fashioned way to connect hard line for pressurized fuel is a 45 degree, inverted flare. That's what the output of a carb fuel pump has, also used for brake lines.
A compression fitting simply squeezes around the outside of hard line.
I'm guessing that kit was made for hard line with compression fittings between the tank and fuel pump, non-pressurized. Then the pressurized fuel between the pump and carb uses the braided line with JIC fittings. The JIC, like an inverted flare is for higher pressure.
A compression fitting simply squeezes around the outside of hard line.
I'm guessing that kit was made for hard line with compression fittings between the tank and fuel pump, non-pressurized. Then the pressurized fuel between the pump and carb uses the braided line with JIC fittings. The JIC, like an inverted flare is for higher pressure.
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Thread Starter
TECH Enthusiast
Joined: Apr 2006
Posts: 630
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From: New York City
this is the fitting that comes with the kit i assume. no flaring? http://store.summitracing.com/egnsea...alse&N=700+115
Not sure what fittings come with that kit. Also dont know what pressure the compression fittings are rated for. My preference would be hard line with inverted flare fittings or braided line with JIC fittings.
Russ
I used a 3/8 line from an early 90s silhouette minivan that was braided stainless to that vinyl stuff the oem's use.That piece went from the engine to the output of the filter which I installed on the framerail just behind the driverside door. From the vette filter to the tank I used 6 AN braided stainless and appropriate fittings. However, I think hard line would be an improvement.
Joined: Sep 2004
Posts: 3,148
Likes: 12
From: Downers Grove, IL
I would be ok with compression fittings on the fuel line. Not only did I use a couple in my conversion (I prefer to double flare it, but there was one place where that wasn`t possible) Plus, if you look at the aftermarket fuel line repair kits they use compression fittings.....and they wouldn`t do that unless it was safe, that would open them up to a ton of liability if the compression fitting ever let go.
There is no problem with using compression fittings on fuel lines. Shouldn't be a worry to anyone.
On the braided fuel line, make sure you get the type with a teflon liner. I have known guys who claim the all braided lines will stink up the garage after a time.
On the braided fuel line, make sure you get the type with a teflon liner. I have known guys who claim the all braided lines will stink up the garage after a time.
Thread Starter
TECH Enthusiast
Joined: Apr 2006
Posts: 630
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From: New York City
o k hard line it is , but now i have another question - aeroquip socketless? it is rated for pressure . i see STEALTH 71 used it with no problems. i spent a few hours looking at fittings on line and other threads. I"ll make some calls today and get some technical info on it. yhanks for the replys, JOHN
You can use the a 37 degree flare with a nut on the aluminum line and connect to a JIC fitting, rated to 250psi. That just seems better than the compression fitting. And I could not find a pressure rating on the compression fittings. Did anyoneelse see the rating anywhere?
BTW, I'm starting my fuel system too, so I need to order stuff.
BTW, I'm starting my fuel system too, so I need to order stuff.
I'm using Swagelok stainless compression fittings, a reproduction 3/8 stainless hard line with the barbs cut off the end, and Aeroquip -6AN socketless hose and fitting.
The Swagelok 3/8" compression fittings are rated for around 4000psi--see the Swagelok datasheet for exact numbers, but I know they were adequate (and approved by the TX Railroad Commission) for 3600psi compressed natural gas lines. These fittings are MUCH more reliable, safer, and easier than flaring the tube.
The Swagelok 3/8" compression fittings are rated for around 4000psi--see the Swagelok datasheet for exact numbers, but I know they were adequate (and approved by the TX Railroad Commission) for 3600psi compressed natural gas lines. These fittings are MUCH more reliable, safer, and easier than flaring the tube.
Too bad the kit's blue/red. It's $71.95 for black fittings (includes everything in the kit but the tube cutter -- add a 'B' at the end of the fitting PNs). I'm trying to get a hold of someone to ask if I could substitute black fittings for the kit price of $62.95.