MFI 3-D space cam questions

[356RS]

Can the MFI 3-D space cam wear and cause the A/F ratio go out of specification? Can the space cam be removed and checked out? Is there any ID marking's on the space cam to identify if it's for an E, S or RS? I really enjoyed Jeff Higgins "MFI open heart" and just need to know more.

[jcge]

Mark - Bosch list the space cams as "fast moving parts" in the service parts literature - I assume this means they were replaced with some regularity. Given the space cam is the base "map" for alpha n fuel control, any wear would effect the quantity of fuel deliverd, and therefore AF ratio.

As for how to check the profile - I have one data point of reference - the space cam in my 911E pump has a grey (organic ?) coating - I assume any wear would remove the coating, and your MFI technician would replace the cam if it showed a worn coating, thereby eliminating the need to measure a complex surface. I recall a reference to this coating somewhere, but I just cant find it.

Here's a list of the pumps, governors and space cams listed by Bosch for Porsche that I know of - please feel free to add to the list

The V markings are stamped onto the space cam - at least for the RSR space cams. I've never seen a space cam out of a production car MFI pump. I have only seen one other marking "V114" but I don't know what model it comes from - maybe the production car space cams are similarly marked. I'm sure others on this forum have and will contribute accordingly.

Note that there are 2 different widths of space cam - those in the early pumps (up to and including 0 428 126 012) were narrow (using the roller follower) and the later style (2.4L "R3" pump numbers 0 428 126 013 onward) was wider (using the ball stylus type follower). Refer to Repair Instruction VDT-WJP 711/1B Suppl 2 Ed 1 (in the MFI resource pages)


Ref Bosch EDT-EVP 211/32 11.1973

Regards,

John

[356RS]

Thanks John. Can a 2.7RS space cam be installed in a 2.2S pump? If the early pump space cam in narrow and the later cam wider, is it possible to have it installed? Or do you have to use a later pump?

[jcge]

I'm sure it's is possible to have it installed - but I don't believe its just a straight swap. You would also need to change (at least) the follower lever to the appropriate type. (late model wide cam uses 1 421 960 043 ball stylus type - early type narrow cam uses 1 421 960 038 roller lever assy)

There may be other parts required as well (to account for the changed length, altered transmission ratio to the rack etc). I'm sure those with access to the necessary parts and calibration equipment (eg Koller & Schwemmer, Pacific Fuel Injection, Supertec Performance etc) could achieve this for you. A balance between starting with a pump that is close (parts wise), vs many change parts - given the limited availability of NOS vs used parts.

Sorry I couldn't answer your question directly.

Regards
John

[jcge]

So ...the question remains unanswered

Do production MFI space cams have any identifying marks or part numbers stamped on them ???

Anybody ??

[kenikh]

One point to note: I am nearly positive that the 2.0 space cams cannot be used in the later single solenoid pumps.

I have not seen markings on the space cams I have held, but should have looked closer.

BTW, where did you get that graph? I have never heard of or seen the referenced 003 and 007 pumps for the 2 liter 911S (only 001 and 005).

[jcge]

The table above is something I've been compiling for a while

The applications came from the Koller+Schwemmer website. K+S are the appointed servicing agents for Bosch & Kugelfischer MFI. You can download the application (and service cost !!) table from here.

Year info in the above table came from CMA - and the space cam numbers are referenced at the foot of the table (and relate to the specific EP/RLA derivitive).

But please note - I am not an expert in these systems (others on this forum are...) and I'm trying not to speculate about what is possible or otherwise with MFI and interchangeability of part or applications. I'm just trying to compile factual information with references where I can.

Kenik - do you recall seeing the "grey coating" on the space cam (and if you did, was it intact or worn) or was it just plain steel ??

Regards
John

[356RS]

John, I took apart an 72 "E" pump, number 0408 126 014 today. There is a ID number "54" on the space cam. See pictures below. Sorry, tried 4 times to attach photos but it said too big. I'm down to 640 x 480 but still no go.

[jcge]

Thanks Mark - would love to see a photo

I'm guessing that "54" is an abbreviation from the last 2 digits of the part number for the 2.4 E (wide) space cam.

1 422 200 054

Not too difficult to figure out the rest !! (a couple of other data points should confirm this - an I'll update and post the table accordingly)

Could you measure and post the width of the space cam contour surface - would be great to know what is "narrow" and what is "wide" - I think they are about 4mm (0.16") different

Thanks

John

[jcge]

Originally Posted by jcge

do you recall seeing the "grey coating" on the space cam (and if you did, was it intact or worn) or was it just plain steel ??

Here's the grey coating I'm talking about...(this is on a narrow space cam 2.0 E pump) Photo taken looking into the back of the pump. You can see the roller follower (steel ball) in contact with the grey space cam contour surface. You can see the contour - thick edge of the cam to the right (CW), slopes down to the thin edge on the left (CCW). Below are the flyweights (left & right) and their associated control/part load springs.

If someone could post a similar shot of a 2.4L pump for comparison purposes it would be helpful to see the difference in the type of follower (roller vs ball stylus)

[356RS]

John, This is the ID number "54" found on the space cam of the 72 E pump I took apart yesterday.

[jcge]

Thanks for the photo Mark

Surely the "54" refers to the last digits of the Bosch space cam part number in the table above

Also, I found the reference to the grey coating (your space cam does not appear to have the light grey coating based on your photo..but maybe its just the lighting/contrast, or perhaps another differnce between the narrow and wide space cams....)

PED 6 KL Repair Instruction VDT-WJP 711/1B Ed 2
Section 3 Inspection & Repair
"As far as the governor is concerned, it is essential to ensure that all component parts and bearings of both governor and correction unit have not suffered any wear; these parts must be renewed even when slightly worn. The cam should be renewed if the bonderized surface layer has been damaged or shows roller tracking"

Perhaps the "bonderized" coating serves two purposes. Firstly to minimise friction & wear between the space cam and its follower, and secondly to provide a simple visual means of inspection (vs detailed surface contour measurement) of the space cam for wear or damage.

A few more data points should answer this question.