CIS distributor membrane part number?

You'd better call Larry Fletcher (fletch62) before you take that apart. If I recall correctly that part might be unavailable.

 

Geert Jan Schreurs has made reproduction membranes for the 6-cyl CIS fuel distributors, but I don't know if he's ever done something similar for the 8-cyl CIS fuel distributor:

http://www.ferrarichat.com/forum/showthread.php?t=341059

His website is: www.ferrari400parts.com

Might be worth giving him a shout if Larry doesn't have an option. (AFAIK, a Bosch PN for either membrane has never been posted.)

 

I have pulled the FD for the 308 apart and cleaned and repaired them.

Not too big a deal. The main seal is reuseable. But you REALLY got to want to take the time to clean it BEYOND CLEAN (I spend about a week cleaning and recleaning mine as the micro rust will seriously throw off the feed amounts of gas) AND the opportunities to screw up delicate parts seriously exists.

The amount of dirt in them is UNBELIEVEABLE. How they work I have no earthly idea. Pulling a number out of my butt, I bet 80% in existance are loaded with pure crap and our cars run in spite of the FD, NOT becasue of them.

Check with Geert Jan as I know he was working on the 8 cylinder vision (o-rings and main seal) as he and I have worked on parts sourcing together. He might have something working/finished now on the 8 cylinder FD.


WHEN YOU ARE DONE, IF you are determined to go DIY, then STILL send it to Larry Fletcher for tuning. If you don't do that, you are just wasting your time.



Disclaimer - I have no monetary interest in either Gentleman's effors.

 

Someone needs to document the proper rebuild of a fuel distributor and start a thread. Couldn't find one ...

 

www.porsche928forums.com/download/manuals/CISRebuild.pdf

 

What is there to tune on the fuel distributor? Cant think of anything.

 

Underneath the domed caps with the hex holes. There is the adjustment pins for each cylindar feed chamber. They must be tuned each one against the 7 others and it is a very fustrating exercise if you really want the most out of your car. Each adjustment to any one adversely effects the flows of the others.

Many Pros here will not touch them. Only pain loving crazies D) like Larry Fletcher will.

 

Use search. A very good tutorial was done by Geert Jan in the TECH forum. He normally posts in the 400 forum.

 

But those are for balancing the entire system, plumbing, injectors etc. Surely it is not possible to do that with the fuel distributor "standalone", ie by sending it to someone (or maybe its necessary to send the injectors as well?). I am not sure that it is correct to say that the OP will be "wasting his time" if he were to disassemble the FD and clean it without doing this balancing procedure afterwards.

 

I freely admit I am not really well versed on Bosch CIS systems, but everyone I talked to including Bosch GmbH said "Tune It" or have it done. So I did. Larry said that one was "way out" compared to the rest. Several others were not as far out of Bosch specs but out non-the-less.

 

Does anyone know a reputable place to tune them in Europe?

 

Thanks! Very nice tutorial!

 

Bosch in Nurnburg or Stuttgart. Very expensive though.

I sent mine along with my WUR to Larry Fletcher in the USA. Very reasonable comparitively speaking. Very reasonable.

 

Looking at the procedure in the QV manual it states that the aim of this procedure is to compensate for differences in the fuel delivery among injectors. Using the (very expensive) tester the injectors are fitted into the tester which measures the delivery of each one.
Then the adjustments on the FD are done to equalise them at 3 different openings of the metering plate.
But I guess this could be done off the car as long as the same injectors were used for the calibration process and not mixed up.

 

That means that when you change the injectors with new ones you don't know how you end up.... So changing injectors should be followed by a distributor calibration?

 

No, the CIS injector has no effect on the amount of fuel delivered (that's why Larry does not need your exact injector set to calibrate your fuel distributor) -- the amount of fuel delivered by each injector is solely controlled by the size of the slit opening in the fuel distributor and the pressure drop acting across the slit opening (but it may never have been set-up super-Fletcher-well ). If you disassemble/reassemble the fuel distributor (and wanted it to be unaffected), you'd need to make sure that you kept every internal component in the exact same location -- but even doing that is no gaurentee that it won't change because a coil spring might shift a little, or you can't repeat each spring's exact rotational position, or you can't compress the membrane the exact same amount, etc....

 

Ok thanks for clarifying Steve.
Best not be opening that up then.....

 

Sorry to bring this up again but I am still curious about these adjustments. The adjustments are not shown/mentioned in any K-jet documentation nor the workshop manual (which only describes a check).
On Jan's site (Ferrari400parts.com) there are details of how to check the flow rate but he states that if the rate is not equal the fuel distributor just needs to be cleaned.
What form do the adjustments take, what exactly is under the cap, are there adjustment screws?

 

So you want your head to explode?

The figure on page 101 of the Aird book and Fig 5-7 on chapter 6, page 22 of the Probst book show a cross-section of the K-Jet with Lambda fuel distributor. Under the "cap"/cover screw is a set screw that pushes on the back end of the spring that pushes on the differential pressure valve and sets the pressure difference between the upper and lower chambers. This alters the upper chamber pressure (for a given lower chamber pressure) and changes the amount of fuel delivered for a given size slit opening (since the amount of fuel delivered is proportional to the pressure difference across the slit times the slit size opening):

fuel delivered = K * (system pressure - upper chamber pressure) * (slit size opening)

If you don't have access to one of those books, give a shout, and I'll post some scans.

 

I do have the Probst book but it must be different because fig 5-7 is on page 17. But, I read through it again and looked at the sections I had skipped before which relate to the KE-Jetronic system as opposed to K-Jetronic. Sure enough I can see this adjustment on a diagram but it seems specific to the KE system only. In my book its fig 5-16 on page 26 of chapter 5.
Then I found another diagram on page 30 of section 5 "comparison of differential-pressure valves" which shows the valves for K-Basic, K-Lambda and KE. The KE does have these screws shown. Does this mean US cars have the KE system? I thought they has K-Lambda.

 

My bad -- it should be chapter 5, page 22, fig 5-7. On KE-Jet, the adjustment screw (and spring) press on the bottom of the differential pressure valve (and in a centered manner) -- while on the K-Jet , the adjustment screw acts in a sort of off-axis way on a "cup" at the back end of the spring which then acts on on the top of the differential pressure valve.

In those figures on page 30 of chapter 5, they just left out the adjustment screw and "cup" (that acts on the back end of the spring) from the K-Jet and K-Jet with Lambda systems for simplicity.

 

Got it! Thanks.
Looks like they also left out any mention of these adjustment screws anywhere in the book for simplicity as well!

 

"No User serviceable parts inside"

The paragraph at the top of page 7 in Chapter 6 explains why they don't explain it...

 

Yeah. What Steve said. Sorry as I am in Bratislava and my phone is a pain to type on. Plus I do not have the references Steve cites.

Steve, can I get copies?

PS There is a Ferrari Cali in the hotel loby. The hotel owner parks his car there. The hotel security is only matched by the Prez Residence across the street.