924Board.org

[Project-924-1979]

Hello everyone,

The fuel lines that go from the fuel distributer to the fuel injectors are not looking great on my car(and probably a lot of other 924's). The outer hose was cracked and almost falling of. and the inner tube got very hard.

This is a known problem on the 924, from what i have been able to find there are not any solutions that propparly solfe this problem. And I'm not a fan of getting some rubber hose made. In my opinion it will look very bulky.
So I did what any person would do and cut the polyamide hose from the metal tubes that go to the injectors, even though there is no replacement. I've done a couple of evenings for googling but the hose that is used not not avalble anywhere.

But what if I can get the polyamide line made to original spec. I've found a company which might be able to make them to original size and spec. The only problem is that you can't really get 3 meters of hose made. Production starts at a couple 100 meters at least.

So I was wondering if I would make a set a inner and outer fuel lines for the Porsche 924 would anyone be intrested? And whatwould would you spend on such a set of fuel lines? I might also offer the service of fitting them to the metal hard lines if there is enough demand. If I end up offing a fitting service I might also make a jig to pressure test them.

let me know what you think.

Ryan
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Restoring a late 1979 Porsche 924. This is my first car and my first attempt at restoring a car.
Learning a lot along the way and doing as much as I can myself.

[morghen]

You know what i’m going to say
Get the EFI kit, looks just like the kjet, you get new fuel lines with that, works better, endlessly adjustable..modern..but still looks like the original.

I also looked into rebuilding my lines when i was on kjet, could not find anything that looked safe and easy to get.
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Supercharger and EFI kits
https://www.the924.com

[Project-924-1979]

I know, but I the lines are quite big and I think the old lines look better. And I want to keep the K-jet system.
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Restoring a late 1979 Porsche 924. This is my first car and my first attempt at restoring a car.
Learning a lot along the way and doing as much as I can myself.

[Cedric]

Mines also has that outer layer falling off, they still work but it doesnt look great. Havent seen anyone doing these type of hoses, but I know several others over the years have searched for it. You can of course buy fuel lines from HEL or so but they are bulkier for sure. I planned on replace mine nad it would be nice with oem looking ones, not sure there is buisness enough out there since lines already are on the market with normal braided PTFE hoses though.
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1980 924 Turbo
www.instagram.com/garagecedric/

[Raize]

What’s special about the nylon tube?

[Project-924-1979]

It's a weird size. Id 1/16" or 1.6mm OD 1/4" or 6.35mm and if you find it somewhere the material needs to be correct too: PA12 not PA6
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Restoring a late 1979 Porsche 924. This is my first car and my first attempt at restoring a car.
Learning a lot along the way and doing as much as I can myself.

[Nobbi]

Hello all,

i went to my local Farm-Trakor repairshop. They had the braided lines available on a roll of 10 meters.They asked 75 euros for the complet set of lines.Absolut original look.

best wishes,

Nobbi
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NA 924 - april/1977- 4-speed-audi gearbox.
500.000 km with fun.....and new toy:Porsche 944 S2 Cabriolet.Other car Daimler c-class cabby,brandnew..Plus : DEUTZ 4005 tractor Built 1969

[Project-924-1979]

Good news!

I've just heard back from the company that I contacted to see if the can make the the special hose for the K-jet injectorlines and they can! The only problem is that production starts at 750 meter of hose.

Which means If I decide to order the hose then I'll need to sell 15 to 20 fuel line kits which will be around €150 per kit. The kit will include the inner PA tube and the outer rubber sleeve. It will be to original spec and so sould last another 40 years.

I would love to make the fuel lines for the k-jet system available again, but cost are quite high so if there are atleast 15 people who are will to pay around 150 for some fresh lines then I'll consider ordering.

I'll post some pictures on here soon of the fuel lines I am talking about just to clarify.

Ryan
_________________
Restoring a late 1979 Porsche 924. This is my first car and my first attempt at restoring a car.
Learning a lot along the way and doing as much as I can myself.

[Beartooth]

I thought the polyamide line sized for the injectors, warm-up regulator, and frequency valve was available; could it be 2mm? Partsklassik sells several sizes of polyamide, and I'm wondering if this might be the one: https://www.partsklassik.com/p-4685-polyamide-line-2mm-thick-wall.aspx. Even if it is, the other problem is that it takes some special tools to press them together (which could probably be made, but obviously it's a pretty complicated DIY). Another possible resource is https://www.unobtaniumsupply.com/. He's a Ferrari specialist, but some models used k-jet, and he came up a couple places when I searched for polyamide fix/replacement. I think there are places you could send the old lines to and have them completely refurbished (as in replated - I think cadmium-plated - with new polyamide lines installed), but I can't find any listed, so I can't say for sure. If there's no one to be found doing such a thing, it's definitely an opening for someone interested in a side-hustle (or maybe full-time business). If you dug far enough, I'm sure you could get a bulk of all the polyamide hose sizes you'd need, and the plating kits aren't ridiculously expensive. There are a lot of parts from this era that were cadmium plated (especially on my Benzes).

All that said, if you can find a used set of lines cheap enough, that might be a good way to go. With mine, the outer rubber sheaths are all cracking apart, but the lines themselves look ok and there's no sign of cracking or leaks. There would be peace of mind in replacing them - you're taking some risk even if there's no sign of leakage, but probably it's an acceptable risk to some. Original lines are something to inspect, and absolutely be alert for the slightest whiff of gas under the hood, but it doesn't seem like something to replace "just because." For those needing replacement, I can see sticking with polyamide just for the factory look, but also, they seem to last a long time if nothing crazy happens to them. I don't think alternative hoses would give unacceptable life, but I wouldn't be surprised if they needed replacing every ten years or so. As compared to many 40+ year-old original polyamide lines still running around.
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1980 931 diamond in the rough

[Raize]

If 2mm would fit securely on the barbs, there is cheap and available 5mm/2mm PA12 tubing.

If it was secure on the barbs that could be a solution, the working pressure rating is 53 bar which is obviously 10x what the K-Jet ever sees.

https://www.shop4handrail.co.uk/Metric-Tubing-Nylon-PA12---13mm-to-28mm-30m-rolls?VariantID=24537&PPCT=1708351357

Also pretty sure cadmium plating is not allowed these days.

[morghen]

The trick is to make sure the hoses stay on the barbs.
That was what i was always afraid with just replacing the lines.
The factory surely did some controlled process in which they melted the inner tube on the barb somehow to ensure the hoses stay.
_________________
Supercharger and EFI kits
https://www.the924.com

[safe]

I've replaced these lines once or twice. I don't remember where I got the line, but it wasn't very hard or expensive, it was local.

You don't heat the lines, it must be done "cold". You push or tap in the fittings, its greatly simplified if you have a fixture holding the line in a vice.
You can make fixture from two wood blocks that you clap together with a drilled hole in between.

The lines needs to be cut really neatly otherwise it will split when you push in the barb fittings.

There is some information here:
https://www.unobtaniumsupply.com/Downloads/Instructions/CIS%20Barb%20Insertion%20Tool%20Instructions.pdf


BUT, these lines lasts FOREVER, I've never seen one needing replacement other than from external damage.
The outside rubber perishes, but that is just insulation, has nothing to do with the integrety of the actual fuel line.
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/Magnus, Stockholm Sweden
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Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe

[Project-924-1979]

Yes. I heard from some other people aswell that when you have fixture it's not tha hard. If I end up making a kit of fuel lines I might supply a fixture with it for ease of installation.

The only problem is that quite a few people said that there sould be some demand for this, but but no-one has really shown enough instrest and said, "I'd be interested in buying something like this. And the line which I can get made will cost far more than €1000. So I really need so have atleast 10 people that will buy one before I take this gamble. I understand it's a bit shady to buy something of someone you have read about on the internet. So I'll just be patient and see if I can gather enough people to make this happen.
_________________
Restoring a late 1979 Porsche 924. This is my first car and my first attempt at restoring a car.
Learning a lot along the way and doing as much as I can myself.

[Project-924-1979]

[Beartooth]

Yeah, I'm not sure on cadmium - it still exists on some level (I hear there are industrial and aerospace applications that use it to this day), but I can't find any DIY plating kits that are actually cadmium. There's a kit from Caswell plating that always comes up, and I've found some posts indicating it was cadmium not so long ago, but as best I can tell now, it's zinc plating with something to give it a yellow finish. https://caswellplating.com/copy-cad-reg-and-zinc-plating-kit-1-5-gal.html I'm tempted to try it. If it's not cadmium, I have to wonder if it's anything as durable as the original, but it might look good for long enough to be worth it. I do believe if you offered a service refurbishing the fuel lines and marketed it enough, you could make money. The trouble with a group buy is there's not enough need for it. Mine don't leak and I'm willing to put up with the ratty look, and it seems that's common. On the other hand, put up a website where it can be an impulse buy - plus get connected with the shops that do top-dollar work on k-jet cars - and eventually you'd turn a profit. But it'd take while to catch on, for sure. If it were easy, everyone would be doing it!
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1980 931 diamond in the rough