Nylon fuel line

[dumptuck]

In my research for what lines I should buy, I have come across a confusing subject. It seems like everyone is using rubber lines or braided rubber lines, yet nobody seems to be using nylon. From what I have read, nylon lines are used in most modern vehicles, due to the fact that they won't degrade from modern fuel, high abrasion resistance, great bend radius, higher pressure rating than rubber, and very cheap to buy. So why is nobody using this magic material? Am I missing something?

Also, how much line should I buy for my engine? I have a 1600cc single carb, I believe it is a dual port (as my bus is a '71) but I am not certain.

What size diameter lines should I buy? Some places I read tell me I need 5.5mm, some tell me 1/4", some tell me 5mm. Which is correct? Does it actually matter?

Lastly, where can I find a guide for where all my lines are? Ratwell only seems to have a tutorial for FI, Muir and Bentley don't even seem to mention fuel lines in any detail for some reason.

Yes, I have read through the fuel line thread, but for some reason none of this is covered in there as far as I can tell (I might be wrong, maybe I missed something). Thank you all once again!

[Dogo]

This^^^ Why isn’t anyone switching to nylon lines?

[Hoody]

Ray will be chiming in shortly with everything you will need to know about nylon lines. The fix for a type 4 engine is simple by using Gates Barricade. My guess is that properly crimping the nylon to the fittings to get a flawless seal will be a challenge.

[Tcash]

[Dogo]

Saw these fittings being used. As far as I know, line is warmed up and fitted, done. And they are quick release.

[Dogo]

Thanks, Tcash. Just saw your post after posting the above pics

[Tcash]

The biggest problem I see would be the fittings.

[Dogo]

I’m not familiar with type 4 lines or fittings. I’m thinking for my upright. In the pics I posted there looks to be a transition adapter to be able to fit that quick release fitting. I would assume that would simplify the fitting situation

[SGKent]

a solution in search of a problem. Use Gates Barricade. It is also approved for fuel in smog states.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[raygreenwood]

The barbed fittings.....are only lightly heated. The big deal is that where barbs are actually used....they are typically heated to maybe 200° F.....and "pressed" in with a ratchet style tool.

Using barbed fittings is only really necessary in certain areas where getting to the joint is not an easy access.....meaning connections inside the car body, inside the fuel tank etc.

Otherwise....for instance.....in that picture of the fuel filter that Dogo posted......you can get those same fittings....with female quick connects.....on both ends.

This changes things a bit. ...but your brain first starts thinking....."but the male fuel line still needs a flange for the female quick connect to latch onto".....right?

Yes.......and those can be installed with barbs. But unlike the plastic barbs you see in Dogo's picture....the barbed, flanged connectors do not have to have HUGE ridges on the barbs like those plastic ones. Metal ones do not compress at all. All it needs is a bump....and you CAN clamp them.

You can even insert fittings with a dead smooth fit and slight corrugations...heat to about 225° F with a heat gun....and simply crimp the outside.

There are also double ended female line connectors that use a slightly different clip system and use the same internal o-rings to seal. They are similar to air line connectors. They are leak free to over 150 psi.

Nylon is a great solution for everywhere but inside the engine compartment. You find ambient temp range listed right at 212° constant. Not because it will melt....the melt point of Nylon 11 is between 430° and 500°F......but because it starts fo expand enough that at highest rated pressure.....it may leak at the fittings.

So in our cars..... long run sections with no fittings.... passing through the area forward of the engine compartment to the gas tank....or even farther forward to those of use with types 1, 3 and 4 cars with front mounted fuel tanks.....even getting radiant heat upwards to 250° + from brakes and transmission.....is not a problem.

But the OEMs for the most part try to keep nylon out of the engine compartment where it can get close to manifolds. So for instance....with a watercooled car that has a transverse motor and the exhaust manifold exits at the rear next to the firewall....like my Golf.....the nylon line dead ends at the firewall at a pressure flange and has a short rubber flex joint line with swaged fittings. It connects to short clamped down formed metal lines....and then clamps to the fuel rail.....which is a molded glass filled polyphenylene thermoplastic.

This method is actually not horribly far from what VW did in our cars with D and L-jet. They just take it a little farther.
A modern variant in our cars if they were still in production.....would be nylon from the tank to pump, from pump to engine compartment....ending at a quick disconnect bulkhead fitting on the sheet metal, a high quality, swaged rubber flex joint....probably with outer braiding.....to a push fit connector on the metal fuel rail for #1 and 2 that we already have.
Then another rubber connector hose to a bent steel line that say....runs along the #2 injection runner.....or you can make it all one piece all the way up to the CSV.....which would either use threaded fittings or another pair of short clamped rubber parts.....joining to another formed line that goes to 3 and 4.....and a short clamped flex line to the regulator.....which connects on the forward side of the bulkhead to push fit nylon back to the fuel tank return.

While I agree with Hoody that the Gates barricade is a pretty good solution.....I am not convinced its a perfect solution. There have been some hit and miss problems with this hose. Hard to say if its materials or build quality...or even installation issues.
The other issue is cost.

For a long time....even back in the early to mid 90s....on D-jet cars....it was recommended to change your fuel lines out about every three years. Not because they failed....but because even back then in hot climates....they start hardening up. Back then at $1.75-ish a foot.....it just was not a big deal spending $45 on a 30' line change.

Now a full change out every 3-4 years.....will cost 2.5X. Thats getting prohibitive. I can see why the OEMs have gone to non high heat areas of all nylon lines ....at about 25 cents a foot or less and no issues with any fuel.

They are fighting in legislation to behin introducing E-15 this summer ....stupid.

Ray

[Wasted youth]

[aeromech]

Carbureted engines use 5.5mm hose. If you could find nylon fuel line in that size you’d be golden. Since you can’t then you need another hose that’s 5.5mm and will withstand alcohol in our fuel. I found it. It’s made by Honda for things like pressure washer engines. Great stuff. I buy it in 25 foot rolls. Can be found on eBay. You can buy shorter lengths.

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F173085272953
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[raygreenwood]

[aeromech]

The hose size has to fit the fitting size. Using 5/16 hose on a 5.5mm fitting is asking for a leak/fire
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[SGKent]

[raygreenwood]

[aeromech]

Never seen it in 5.5. Do you have a link?
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[raygreenwood]

[SGKent]

Ray - am going to continue to use the five layer Gates Barricade hose..
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[SlowLane]