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Discussion in 'Technical Q&A' started by Verell, Feb 20, 2008.
And if anyone needs the plastic fuel line clips just PM me.
my name is Ruben from Hamburg Germany. I`m driving a 1984 Porsche 924 using exactly the same Cohnen Injector / WUR Lines like the Ferrari.
I've already restored my WUR Lines using your description. Thanks for that! Very helpful indeed as it seems that in Germany people tend to buy completely new lines directly from Porsche that cost around 100 Dollar the piece.
My question now is about the injector lines. Using the 0305 for the WUR lines i recognized that the original injector lines use a 1606 diameter (1,6mm ID, 6mm OD) as you already wrote. This line is impossible to get because it's not built anymore.
You also wrote that you would replace those injector lines with a line of an ID of 3,15 and an OD of 6mm. Did that work? Are there no problems with the engine? I can get a COHLINE Line with an ID of 3,45mm and an OD of 6mm at my local dealer.
I'm a little bit afraid that the bigger ID lowers the pressure on the injectors, so that the engine won't run properly.
I'm really looking forward for your answer.
All the best,
No, hydraulics does not work that way, once the slightly larger interior volume is pressurized, by the pump output...it's the same from one end to the delivery point???
If I'm right....welcome!!!
thanks alot for your answer. Sounds logical to me
So it should work, as long as the inner diameter doesn't widen out under pressure.
In that case a smaller diameter could make a difference. Or am i wrong here?
As i've now seen on a posted picture above Verell seems to use the 6x1,275 mm lines for the injectors on his replacement sets. That's exactly the line that i meant.
Thanks for your welcome. By the way, you have to apologize my english. I hope it's not too bad. That's what we learn in german schools...
All the best to you, Ruben
Only to the maximum flow 'possible' thru the line, volume.
As the injector only fires periodically, max volume is not really a concern.
Only the sustained delivery pressure maintained by the fuel distributor.
You realize though, you are talking to a carbed Ferrari (x three) guy....LOL!
But Verell is here a long time, and is a smart guy (and a Texan too!) so, if he says "it's good" you can have confidence!!
You are doing fine!
Yes,Ruben, That is the line you want to use. I have sold many fuel line kits to Ferrari owners, and a surprising amount of custom kits to porsche, volvo, and audi customers with K-jet CIS systems. All feedback has been positive.
My apologies for not responding sooner, but was shut down due to hurricane Sandy. We came thru it fine except for a few hours power outage.
That is mostly correct. The injectors
That is the critical parameter, The distributor has a mechanical feed-back system that precisely controls the average pressure at the inlet of each of the injector lines & supplies sufficient fuel flow to maintain that pressure.
Actually, these injectors continuously flow fuel as opposed to the newer electronic injectors that control fuel flow by the on/off duty cycle. In CIS the amouth of flow is controlled by the fuel line pressure. The injector nozzle does vibrat at a fairly high acoustic frequency to create the spray pattern. What the P* 911 guys established as important is that the injector line's walls be sufficiently rigid so that the vibrations do not significantly interfere with the line's flow.
thanks for your answer and good to hear that. Indeed i hope all of you were not badly affected by the hurricane. We hear a lot of bad news on TV and radio here...
Then i will take the 6x1.275. I was a bit unsure about that as there seem to be significant differences in the material. The text on the original injector line says:
Cohnen 311 1606 PA 12 h nf
1606 seems to be the diameter (1.6 mm ID, 6mm OD)
PA12 is the material
h is "Hart" - the german word for "hard"
nf is "naturfarbend" - german for "natural colored"
The text on the new line (6x1.275) says
Cohnen 313 6x1.275 PA 12 sw
sw stands for "schwarz/weich" - german words for "black/soft"
So the replacement line is made of soft PA while the original line uses a hard PA and has a thicker wall additionally. That's why i wondered if the inner diameter would widen up under pressure causing a bad engine run. I also wondered if the fitting would sit firm enough in a line with an ID of 3.45mm while being designed for a line with an ID of about 2mm and cause no leaks.
Nevertheless. You tested it and it's running. That's fine to me. Seems as if the total amount of fuel in the lines doesn't matter as much as the durability of the line against expansion under pressure as if Tex already suggested?!
So thanks alot for your investigations and your warm welcome.
All the best,
Glad to have you back, as you see I warned him, I had no idea...LOL!
Good things are okay with you.
I always warn everyone "The Season runs thru October" as you found out.
NYC and Jersey look bad, as does the fire in Queens.
Electrical lines are a huge fire hazard, as they come down.
That's a reasonable concern. The Cohline barb'd fittings are rated for a line ID of 2mm or 3mm. I have never encountered the 1.6mm ID line. The Ferrari, 911s & Volvos used OD: 6mm, ID: 2mm line.
It would be best to make up a single line with your fittings & pressure test it up to 150 psi, at least 100psi.
If you encounter a problem with the Cohline 3011.3106 & want to keep your original fittings, there is an alternative that I recently became aware of. Cohline still provides 3012.0206, a SS Braid covered OD: 6mm, ID:2mm 'hard' black plastic line. The braid readily slips off leaving the black plastic line with markings similar to Cohline's black plastic lines. Cohline only sells it in 20 meter lengths. It is extremely difficult to insert the Ferrari barbs into this line without taper reaming it to get them started, but perhaps your 1.6mm barbs would be easier. If you end up needingn it and can't locate it locally, I may be able to help as I have a few meters left over from a special order for a customer a few years ago.
> Indeed i hope all of you were not badly affected by the hurricane.
We were fortunate, lost power a couple of times each a few hours long during the worst of it. That plus a mess of leaves & limbs to pick up in the yard was it for us.
Last fall we had a surprise Halloween snow-storm that took a lot of power lines out due to trees & limbs faling onto them. That & a subsequent agressive trimming back from the I power lines weeded out a lot of potential problems for this year.
We have just resumed production of this tool, which has been NLA for a long time.
This tool is used to restore BOSCH K-Jetronic fuel lines used on Ferrari, Porsche, & others. For details about the tool, see earlier posts in this thread.
You can download instructions for the tool from the [SUPPORT] page of our web site:
To order send me eMAIL specifying the following part number:
K-JETBTOOL - K-Jetronic (CIS) Barb Insertion Tool
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Do you still have the K-Jetronic (CIS) Plastic Fuel Line/Hose Restoration Kit available?
It is for a euro car and I would need only the plastic fuel lines. (all of them)
Shipping would be to the US (Houston).
Yes, in stock. Send email to firstname.lastname@example.org saying you want to order a K-JETP kit.
BTW, you can always find my catalog at: www.unobtainiumsupply.com.
Thanks Verell!! Order has been placed.