Technical installing fuel lines for the masses

Lloyd brought up running fuel lines on his truck.
How about some thoughts on fuel lines.
rubber vs braided. steel vs aluminum.
flare vs push lock.
How about routing the lines from tank to carb. Return lines and venting. .
Clamps and mounting.
Hose clamp styles .

 

Steel line, the least amount of rubber hose that you can get away with. Braided = only the designed to go from steel fuel line to mechanical pump braided line.

Braided stainless covered hose is STREET ROD, not hot rod. Aluminum tube is race car and again street rod and not hot rod.

No frigging copper in the fuel lines, you aren't working on a house plumbing water, natural gas or stove oil.

 

Flared end steel and NO rubber from the mechanical fuel pump to the carb. If you want a filter get an inline with fittings like an AC glass bowl.

 

Not natural gas in this area , propane is OK but not natural , the sulpher dioxide added to the natural gas eats the flares off copper tubing I've refit more than a few homes in the last ,40+ years !

 

I'm in the same camp as the others, no braided, very little rubber (the rubber needs to be better then regular fuel hose, like Gates Barrier brand) flared and steel lines. I know lots of people crapped themselves when I posted about some copper coated steel line on discount, but I paint them black anyhow (the copper is just extra protection if some paint gets chipped off).

Also IF you have the room, a return line isn't a bad idea to head off vapor lock and some over pressure issues. As for clamps, that's a person taste thing, as long as it keeps the line from rubbing through (fuel and brake). I use Kugel line clamps because they're stainless and small (they also get painted black).

 

Amen.

Where you must use aluminium flare fittings, use black or silver.... not red or blue anodised. Red and blue are for 80's street rods and race cars.
Big loops on piping are for moonshine condensors. They might look cool, but those loops are hard to bleed air out of. Your gauges will appreciate non-looped, straight piping.
Learn the difference between double and single flares, AN and SAE (and those 'orrible UK 30 degree flares if you intend touching anything from the UK) and how to identify each... before you buy your fittings.
Lock the thread tape away with the copper plumbing fittings. It has no place on an automotive.
Learn the difference between tapered and straight thread, metric and SAE, and how to identify each... before you buy your fittings.
Know how a flare and a tapered thread seals, and how a straight thread does not seal but only clamps.
Know that thread sealant is acceptable on tapered threads, but nothing else.
Smile every time you forget to put the flare nut on before flaring, crimp a line instead of bending it, or bend left instead of bending right. You are in good company. Few people can honestly say they never do it.
If you are going to build more than two cars, buy a hydraulic flaring tool.
Know that the simple bending tool rom auto parts houses (the one that does about 4 different pipe sizes) will build most jobs. Learn how to "tweak" tighter radiuses with the right tool.
Leave extra line when fabricating. It's easy to cut excess off at the last task... somewhat harder to magic on extra length. Become zen with the idea of having lots of short lengths of tube offcuts in your shop that you cannot throw out.
Yes, you can undo flare nuts with a normal wrench, even a crescent wrench. Flare nuts are a lot softer than normal nuts, often have not been moved in decades, and live under the car in dirty, salty, wet environments. There is a good chance you will round off that flare nut. Consider strongly buying yourself a couple of flare nut wrenches... or get used to using a small pipe wrench to move the rounded off ones.
Recognise that many pipe runs are "not quite right", and put some sideways tension on the nut. Mebbe it was built poorly, maybe it moved as the car flexed on the road, mebbe you bent the line a little taking it off. Flex the pipe in your hands whilst tightening the flare nut until the nut runs up quite a few threads by hand. Only then reach for the flare nut wrench. Starting off with the wrench, with the pipe angle a little off, and nice fine UN threads is a recipe for cross-threading a flare nut.

Cheers,
Harv

 

“Smile every time you forget to put the flare nut on before flaring”

 

As far as fuel lines are concerned, over the years, at least the following materials have been used by the original manufacturers:

Aluminum
Brass
Copper
Rubber (various varieties)
Steel

Copper was used as late as 1966 on high performance Oldsmobile engines.
Aluminum was used as late as 1966 on high performance Pontiac engines.

In 60 years of working on fuel systems:

Have never personally used brass
Have never had issues with aluminum or copper lines
Have had a few steel lines fail, mostly with cracked flares, but a couple actually rusted through
Have had numerous rubber failures; both before and after ethanol

EDIT: It has been a long time, but had a few come in with the red see-through plastic. All were leaking. We wouldn't touch the carb(s) unless the owner upgraded the fuel lines.

I tend to use aluminum, simply because when we were still fabricating fuel lines for multicarb setups, had to buy a LOT to be able to buy it at a reasonable price; so I have 1/4, 5/16, and 3/8 in stock.

If I didn't have the aluminum, would probably just buy steel at the FLAPS.

Jon

 

You do realize that braided steel line with red/blue fittings originated in the aircraft industry in the 50's right, fiat had braided steel oil lines in 52, it's not street rod stuff.

 

^^^ what they said! Also, any lines should be supported when there is a long run, like from tank to pump on engine. The OEs didn't punch holes in the frame and stick those spring clamps over the line and into the holes for pretty!
Plus, the hose clamps were discussed here recently.

 

It amazes me how people will just get tunnel vision on certain things.

Just because they didn't do it they figure nobody did. Such narrow knowledge of the times.

That's the cool thing about real old school hot rodders, they didn't walk around asking what everyone else was using, they were using what they had or could scrounge close by or not what was popular.

I've been around a lot of old Pontiacs in my day and remember the aluminum lines rather well but hey as stated above it's only street rods and race cars that used them so I guess Pontiac got it all wrong 60 odd years ago....

..

 

I use stainless steel hard line for as much as possible, it helps that I have a bunch from a past employer. I always try to keep the rubber or braided lines as short as possible and to a minimum. Also try to have as many flared connections, rather than clamped connections when possible. Just the way I do things.

 

i'm also against using rubber lines. it perplexes me when i see guys on the tv shows using it; they should know better!

 

I used SS on my roadster for both delivery and return lines. Hard to work but pretty polished. I went with aluminum 6an on the pickup. The reason is it was easy to manipulate and allowed me to make one piece that extends from the frame near the tank (where it is connected with nylon covered flex hose and black fittings) and snaked all the way through the frame, crossmembers and all the way to the firewall mounted filter in one continuous run...

where another short length of that nylon flex line is used to the engine.

Using aluminum hard line allowed for a very sanitary install and safe as that fuel line is well protected and shielded.

 

I concur!
Not what most here want to except and I sort of agree that flashy new red/blue stuff really does look out of place on a "traditional" build but that issue can be skirted by using the newer style black/nickel fittings.
Also, a little judicious use of Scothbrite will tone down the red and blue anodizing, at least that would resemble old Aeroquip fittings.

A lot to learn from this book.

 

With modern fuel, wont steel rust internally?

 

I used a lot of aluminum for my main fuel lines with never a problem and will continue to use aluminum.

I like aluminum for a lot of reasons, easy to form, can use compression fittings on it, and I like the idea that any frame flex and the aluminum tube won't have too much stiffness to allow flex with the frame. Again I like to drive hard, after all it's a hot rod right?

As far as rubber hose, I like as little as possible, but to say using too much rubber hose isn't traditional is crap, how many multi carb set-ups had nothing but rubber hoses from the carbs to the fuel block and how many of those fuel blocks were even mounted to the firewall? I can post a lot of pics to prove this point.

It may surprise some but billet aluminum, braided hoses, big tires, etc were around loonngg before "Street rods" ever made the scene, just because you didn't use it doesn't mean it wasn't used by real hot rodders back in the day....

Sorry I just hate these conversations because some think they have the only knowledge or experience on how REAL hot rods were built shaped solely on how they built theirs.

..

 

I also use aluminum line from my tanks to the engine bay, and never had any issues. I convert to braided lines from frame rails to fuel pump, and then bend up all my final runs from fuel pump to carbs using steel. Flare all my lines, as it's the only way I know to do them.

 

There is worldwide "guidance" that copper is verboten on brake lines as it will harden over time and crack. Can't say I've ever cracked one though I too have busted my share of steel lines. I wonder if that guidance is really true, or if it is a myth that got out of control.

Brake (and to a lesser extent fuel) systems go through lots of pressure cycles. Vibration moves piping around if it is poorly supported. There will be some work hardening. But is copper more susceptible to work hardening than steel? I'd love a real materials expert to weigh in on that one with some science.

The science behind the single versus double flare "guidance" I never understood either, until this gentleman explained it really well:
https://dimebank.com/BrakePlumbing.html

Cheers,
Harv

 

This is about brake lines not fuel. However, Harv caused me to try to find the source.

https://4lifetimelines.com/blogs/knowledge-garage/are-copper-nickel-brake-lines-safe

"In the olden days, copper brake lines were a hazard waiting to happen. In 1965, brake lines were the cause of 251,000 car accidents. The Society of Automotive Engineers determined the corrosive deterioration of the steel brake line was at fault.

The industry switched to brake lines made from 100% copper. These lines burst from the pressure causing even more accidents. People demonized the copper brake lines."

Here are SAE publications on this. 80 bucks for the most recent one, and it's been cancelled (?).
https://www.sae.org/standards/content/j1047_199811

Copper seller's group info, worth a read even though they don't talk about straight copper tubing.
https://copper.org/applications/automotive/brake-tube/brake.html

 

JIC fittings, that reduces the amount of thread adapters.

 

I posted this on another thread, I’ll post it here as wellhttps://www.worldwidefittings.com/assets/1/6/World_Wide_Fittings_Catalog_-_body.pdf

 

Anyone using ptfe nylon braided hose? https://hotrodfuelhose.com/collections/ptfe-high-performance-fuel-hose

 

Now that makes sense. Copper is fine, provided you use heavy enough tube for the pressure. I suspect the work hardening stuff really is a myth.

cheers,
Harv

 

AN or JIC?

Know there is a difference… and know the difference makes stuff-all impact for anything other than NASA work

cheers,
Harv

 

JIC

 

Harv, I think it's very possible it's true that it work hardens. If you have bent similar sized copper and steel, you know which one cracks and breaks first!
I grew up during "Question Authority" so I get the unwillingness to blindly accept old tales. However, I also understand that we really don't need to stop vaccinating for Polio to make sure history is right.

That's why I tried to track down some real info. I didn't go into the depths and try to pull up modus of elasticity or other chemical properties, just application of materials in use.
So, while a healthy 'show me' attitude is all well and good, the fact that nobody markets straight copper line for auto use should be a clue. Stuff isn't cheap, either.
https://blog.thepipingmart.com/metals/copper-vs-steel-price-whats-the-difference/

EDIT: add work harden education pdf
https://materialseducation.org/educ...cs/Work_Hardening_and_Annealing_of_Copper.pdf

 

I think the title say's Fuel lines.

 

Yep, that might be the reason I started off with that disclaimer.

 

my 39 Ford had a copper fuel line when I got it. it deteriorated with tiny flakes that frequently stopped up the filter. I use Stainless Steel now