Pelican Parts Forums - CIS Injector Tubing Specs

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CIS Injector Tubing Specs

I need to replace some of the tubing on my CIS.

Does anyone know the specs for the tubing: ID, OD, wall thickness, temperature and pressure ranges.

I plan to use nylon 6. Nylon 11 seems to be a little soft . Any ideas or suggestions?

Any help will be appreciated.

Search button is your friend.

Try nylon CIS as search terms.

As a clue, Jim Sims has a great post on the topic.

Beware of using aftermarket CIS tube.....I used McMaster Carr tubing and suffered a misfire that took me 6 months to figure out that the tubes were the issue.

See this thread for the full story:
http://forums.pelicanparts.com/porsche-911-technical-forum/236328-cis-misfire.html

Jim, my OEM tube is more like 8mm with a 3mm wall thickness (i.e. a relatively small flow area).

Note, I'm still looking for a supply of correct fuel line, my original lines definitely need changing.

Thanks, Stu

Quote:

Originally posted by Jim Sims
Interesting reports. I went out and measured the tubing on an old set of SC lines that I have on hand to salvage the fittings from and the OEM Nylon tubing is 6 mm x 8 mm (1 mm wall thickness). The new 6 x 8 Nylon 11 McMaster-Carr tubing is less stiff but it also hasn't been cooking in an engine compartment for 25 years. There are different grades of Nylon 11, the McMaster-Carr number of the 6 x 8 fuel rated Nylon 11 line is 50505K14. Pulsations are often a FD or WUR problem but if switching back to older, stiffer line immediately solved your problem then it must be the elasticity of the line. Wurth once supplied VW, Porsche and Volvo dealers with metric Nylon 11 fuel line but when contacted they said they no longer carried it but to check with Ford as they had used it as fuel line. Ford referenced McMaster-Carr. Are others experencing a low speed pulsation problem with the new line? Jim

My original 79SC lines were stamped with 6x2 and some german I can't read. They were the original lines, complete with deteriorating insulation. They measured almost exactly 6mm outer, 2mm wall. The used '77 lines I got from Jerry are identical.

The pulsation was much faster than that expected from WUR. Something around 10Hz at idle, getting faster with higher fuel flow.

I used the exact fuel lines you specified. And just in case you're wondering, no, I don't blame you. These things happen.