Upgrading Fuel Line

[Hotrodvw]

They all have their place...but scare me to death in a gasoline application.  I'd consider them w/ diesel on a tractor though in the right locations.

[ian c]

i've used them on refineries etc. and had much nastier stuff going through than petrol

i'm not talking about the copper pipe type compression fittings that you have under your sink though

[Hotrodvw]

Correct......when it comes to gas in a vehicle, I'm peticular about my fittings.  You're talking about Swagel-lok type comp. fittings.  Nice stuff, but I'll still take a flared fittings for fuels.  Just my preference.

[Brian Silva]

Finally ended up running my fuel line through the tunnel. Took About 2 hours or so. I have some pics and will post them here shortly. I ended up using aluminum hard line through the tunnel and using some hose clamps to hold the fuel line against the e-brake tubes in the tunnel. Ended up working out extremely well. The .035 wall alm. tubing is very strong and rated to 25 psi. Seeing as a holley blue fuel pump puts out a max psi of 14, I figured the aluminum would be plenty.

[Brian Silva]

Here are some pics of how the install ended up. I ended up using bulkhead fittings through the tunnel as well as a way to secure the line to the tunnel.






I had the fuel line exit in front of the torsion bar housing and I am going to run braided line from the fitting over the torsion housing to another bulkhead fitting on the firewall.

[Bruce]

They all have their place...but scare me to death in a gasoline application.  I'd consider them w/ diesel on a tractor though in the right locations.

You'd be comfortable with a compression fitting to withstand hundreds of psi of diesel, but you're scared of 5psi of gasoline?  You sure do have a lot of unfounded paranoia.

[Hotrodvw]

Yep........call me stupid. gas is a bit more volitile too.     You guys can do as you like, I'll avoid them.  I see them every week through work.  I don't like them, we as a shop don't like them.  The ones we see for diesel applications are coming from the OEM, which is why they come to see us.............because they're leaking and/or failing.  It's not worth the risk to me to have gas leaking in my VW.  They tend to burn pretty well.

[ian c]

  They tend to burn pretty well.

    

[Zach Gomulka]

Any reason to worry about AL hardline fatigue?

[Brian Silva]

In this application I don't have any worry or doubt. I have secured the line solidly through the tunnel and with the bulkhead fittings at each end, the line is very solid. The only place I would have doubts is in the engine compartment area if your were only using hard line throughout the firewall and to the carbs. I would be a little worried with the vibration creating fatigue. Then again, I would be worried using steel line for that application as well. Only experience will tell. From all the research I have done, dragsters (non fuel injected), airplanes and so on use aluminum hardline for fuel and oil applications (excluding methanol and alcohol of course).  Anyone else have any experience using al hardline?

[Bruce]

  I see them every week through work. 

You only see the microscopic amount that fail.  People don't come to you with success stories.  If they were as unreliable as you think, the companies that manufacture the fittings would go broke.
In my former co, we used compression fittings to seal HYDROGEN gas.  Hydrogen is much more dangerous than gasoline, and we had no problems sealing 300 psi of hydrogen.  Also, hydrogen is the most difficult product to seal since it is the smallest molecule in existance.

[Hotrodvw]

In this application I don't have any worry or doubt. I have secured the line solidly through the tunnel and with the bulkhead fittings at each end, the line is very solid. The only place I would have doubts is in the engine compartment area if your were only using hard line throughout the firewall and to the carbs. I would be a little worried with the vibration creating fatigue. Then again, I would be worried using steel line for that application as well. Only experience will tell. From all the research I have done, dragsters (non fuel injected), airplanes and so on use aluminum hardline for fuel and oil applications (excluding methanol and alcohol of course).  Anyone else have any experience using al hardline?

Aluminum will work fine, but not my personal first choice. 

[Hotrodvw]

  I see them every week through work. 

You only see the microscopic amount that fail.  People don't come to you with success stories.  If they were as unreliable as you think, the companies that manufacture the fittings would go broke.
In my former co, we used compression fittings to seal HYDROGEN gas.  Hydrogen is much more dangerous than gasoline, and we had no problems sealing 300 psi of hydrogen.  Also, hydrogen is the most difficult product to seal since it is the smallest molecule in existance.

Like I said, it's my preference.  I do see the microscopic amount that fail, I assume there are many more out there.  Their un-reliability is only one of their issues.  IMO, comp. fittings are a quick fix, since only two wrenches are required.  OEM's will always use them.  less time on the assy line means more production.  Asfor me and my car.....I won't use them.

[Bruce]

  I do see the microscopic amount that fail, I assume there are many more out there.  Their un-reliability is only one of their issues. 

Of the hundreds and hundreds of them I've installed, I only had one that wouldn't seal.  Replacement fixed it.  Once they are installed and sealed, there are no reliability issues.

[Hotrodvw]

I'm not gonna get in a pissing match about it, it's not worth the time.  I will say this:  The failures are from work hardening or cracking right behind the ferrule.  It's not a sealing issue. 

[Bruce]

In order for work hardening to occur, there must be continuous movement.  Since everyone here knows to strap the line down so it doesn't move, that form of failure won't occur.
If you are seeing stress cracks due to work hardening, the failure has nothing to do with the ferrule.  It is the hard line vibrating that's doing it.  Fix the real problem.

[Hotrodvw]

I agree to a point.  The ferrule's biting action into the wall of the tubing creates a cut, greatly increasing the risk for cracking at that area.  Regardles......I'm not gonna use 'em  Beaten to death......

[Jim Ratto]

I agree to a point.  The ferrule's biting action into the wall of the tubing creates a cut, greatly increasing the risk for cracking at that area.  Regardles......I'm not gonna use 'em  Beaten to death......

hey, how's it going? Are you sure your new engine is going to require larger than the stock fuel pipe in the pan? Sarge runs a healthy 2016cc with 48's and good sized vents and jets, and his car is still stock as far as fuel system goes.
Remember too, if you are "pushing" fuel through the stock pipe (+ psi), instead of "pulling" it through (- psi) with stock pump at engine, you are not going to have a vapor lock issue... fuel will flash (boil) at a much higher temp if it is under a higher psi.

Maybe just run a small electric pump and stock line? Why go through all the trouble of re engineering everything if your motor doesn't demand beyond what the stock line will supply?

do you know the gph requirement of your engine? Needle valve size?

[Hotrodvw]

Hey Jim!  My set up is overkill for anything I'll ever put in it.  It's an elec. pusher pump. 

[Jim Ratto]

Hey Jim!  My set up is overkill for anything I'll ever put in it.  It's an elec. pusher pump. 

Just leave it as VW made it then.... save your time for driving it or swilling a beer.

[reijo5]

Hi , what size and pitch is the fuel tank outlet thread? and did they change in size over the years ? mines a 54
thanks for any help.

jay

[Hotrodvw]

Hey Jim!  My set up is overkill for anything I'll ever put in it.  It's an elec. pusher pump. 

Just leave it as VW made it then.... save your time for driving it or swilling a beer.

I did it all two yrs ago......3/8" front to back. 

[tikimadness]

@hotrodvw wat do you prefer for methanol?

Michael

[Hotrodvw]

For hose?  Parker 836 push lock hose, or Teflon/ss braided hose.

[tikimadness]

Yes but also the main feedline.I suppose it is better to run a hardline front to back instead of all hose?

Thanks for answering,

Michael

[Hotrodvw]

I prefer hardline, if that's not an good option, I'd go w/ the ss braided/teflon lined hose as a second option.  It's great stuff, and will last a very long time if it's not abused.

[Bruce]

Hi , what size and pitch is the fuel tank outlet thread? and did they change in size over the years ?

Don't know the thread size, but the tube changed in 75 for FI cars from 5mm to 8mm.

[Bruce]

Are you sure your new engine is going to require larger than the stock fuel pipe in the pan?

do you know the gph requirement of your engine? Needle valve size?

Don't go confusing people with common sense Jim.  Everyone knows that a stock 5mm fuel line (19mm^2) is not enough to feed a pair of 2mm needle valves (3.1mm^2).

[Hotrodvw]

Hi , what size and pitch is the fuel tank outlet thread? and did they change in size over the years ? mines a 54
thanks for any help.

jay

Jay, I believe it's 20mmx1.0, but don't quote me on that. 

[Jim Ratto]

Are you sure your new engine is going to require larger than the stock fuel pipe in the pan?

do you know the gph requirement of your engine? Needle valve size?

Don't go confusing people with common sense Jim.  Everyone knows that a stock 5mm fuel line (19mm^2) is not enough to feed a pair of 2mm needle valves (3.1mm^2).

Well, I'm not trying to piss the guy's fire out (or anybody else's), but I hate to see guys wringing their hands in angst over parts and work they may not HAVE to do. A situation that I've been in too many times, and I see that runs rampant in this hobby. Just because a stock part isn't "shiny" or made of billet unobtanium doesn't mean its not up to the task.
Again, I think a pretty healthy 2 liter street application can be fed adequately by the stock line IF a pusher pump is used. 150-160hp is probably where the line should be drawn. But again, remember, how the car is used matters probably MORE than cc.
My friend Kyle ran a 2016cc for over 150,000 real street miles (only removing motor for clutch) on the stock fuel pipe. While it was not a drag motor, it was what I would consider a practical, reliable daily driver (90.5x78, cam like Engle 120, 7.8:1, d-ported heads, 44IDF Webers). No way that engine would have gone over 150K had it been leaned out due to fuel delivery issues.
Look at other production cars with similar cc and intake arrangement... roughly 500cc per cyl, one throttle per cylinder... I don't think these cars are running a 1/2" fuel pipe to the fuel rail @ carbs.