CIS Distributor

[DSPTurtle]

Guys,
I'm putting a CIS system back together tonight and am just wondering... does it really matter which injector line goes to which port on the fuel distributor. CIS stands for "constant" so all six are always blowing. What do you guys think about a specific order?
I'm asking because the number 2 & 3 were swapped as I was pulling it apart and I'm trying to figure out if that would have had any effect on a poorly running motor. Found plenty of issues with the CIS already, this is just one more that has me wondering.

[Charles Freeborn]

Technically no. But ze engineerez im ze mutter country vill haunt you in your sleep....
They only worried about a clean appearance and tidy routing.


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[Alan L]

With CIS there is no injection timing, or sequence. they all flow, all of the time.
But, if you want to check injector flows, you need to know which port goes where. So it is handy to have them in a sensible sequence. I have them as they relate to the cylinders and the CIS distributor ports. So I don't make mistakes. #1 CIS port = # 1 cyl etc.
Alan

[boyt911sc]

Originally Posted by Alan L

With CIS there is no injection timing, or sequence. they all flow, all of the time.
But, if you want to check injector flows, you need to know which port goes where. So it is handy to have them in a sensible sequence. I have them as they relate to the cylinders and the CIS distributor ports. So I don't make mistakes. #1 CIS port = # 1 cyl etc.
Alan

Alan,

So which one is #1 CIS port that goes to cylinder #1?

Tony

[Alan L]

The port in center of pic - just to the rt of WUR fitting, is wired to #1 cylinder.
We are talking SC right? This pic is of my SC FD. Then sequentially around to #6.
If you can't make the lines fit and they sit better on another port, fine. As long as you remember if you go to calibrate the fuel head.
CIS = constant injection system, or something similar. Fuel goes in to the FD at system pressure and goes past the waist of the metering piston in all directions , simultaneously and finds its way out thru each of the 6 metering slits to the injectors, constantly. All injectors spray all the time. Simple system - eliminates any timing issues and mechanisms. The fuel/air mix accumulates in the inlet tract above each intake valve until the valve opens and takes a gulp.
Regards
Alan

[Alan L]

For comparison, here is my 930 FD. You can see two spare ports in the front left.
The same FD was used on 8 cyl engines (eg mercedes). For the 930 they just blanked 2 off. Hard to do that with a timed injections system. You could theoretically blank another 2 off and fit it to a 4cyl engine.
Alan

[boyt911sc]

Alan,

I was just kidding.

Tony

[Alan L]

Tony - you had me wondering - because I have seen you posting on solving WUR problems before.
Anyway - I like delving into CIS. I think it is a great system considering the technology of the time.
Best regards
Alan

[boyt911sc]

Originally Posted by Alan L

Tony - you had me wondering - because I have seen you posting on solving WUR problems before.
Anyway - I like delving into CIS. I think it is a great system considering the technology of the time.
Best regards
Alan

Alan,

Do you happen to know Glyn Jones from Christchurch, NZ? He is a Porsche air cooled specialist and owns a Porsche shop and came to Los Angeles last month to pick up a project car. And got to take home a newly rebuilt FD from me too. Nice fellow.

Tony