fuel mixture adjustment

[Bucketlist]

On my "new" 1981 SC which has an earlier modified 930/51 twin plug turbo engine I am curious about the fuel mixture adjustment. When I look this up there is always a reference to the 3mm screw next to the fuel distributor. While I had the intercooler off yesterday for another problem I looked for this adjustment screw but didn't find it. I know where the air adjustment screw is and have used it to raise the idle speed.
I don't have a problem at this time but was wondering how the mixture is set if I have a problem in the future.
Here are a couple of pictures:

[Norm K]

Let the experts confirm, but I believe there should be a spring-loaded post/rod where the grayish allen-head bolt in your first pic (very near the center, at the base of the fuel head) is located.

Yours appears to be missing.

[Pezho405]

Yeah it's that Allen bolt between the dist and intake. But it Should be a spring

[356911930]

That allen screw you are looking at is the plug that covers the 3mm adjustment screw inside the hole. Have a look and see if thisw is not the case.

Rahl

[jsveb]

I believe Rahl is correct. Also, is there no BOV on your engine? If not. I'd consider installing one.

[Bucketlist]

Originally Posted by jsveb

I believe Rahl is correct. Also, is there no BOV on your engine? If not. I'd consider installing one.

If we are all looking at the 5mm allen head in the picture I think that is just a mounting bolt for the fuel distributor.

This engine has an O2 sensor, does that monitor the fuel mixture?

You asked about the BOV?
I don't know, would this be located on the intake manifold?

Do you have a picture of one?

[Ronnie's.930]

The guys above are correct - that is not a mounting screw . . . beneath it is the height adjuster for the metering plate arm (aka: the idle mixture screw). It almost looks like the black piece beneath the allen head screw is a home-made cover plate - remove and see what's there.

BOV - what do the ends of the blue hose go to (looks like to a intake manifold port, beneath the throttle body, on the right, but can't see where it goes on the left)? Maybe the other end is attached to an aftermarket BOV (or should be)? Another possibility is that the BOV is attached to the intercooler (obviously, easy to see if it is), but would need a hose that runs from it to a spot below the throttle body.

O2 sensor - I can't tell in the pics if that is a Euro fuel distributor, or a USA one with Lambda assist - looks like it might be Euro due to the graininess of the metal beneath, but would need to know that to give you any idea what the O2 sensor in your car is used for.

[Bucketlist]

Originally Posted by Ronnie's.930

The guys above are correct - that is not a mounting screw . . . beneath it is the height adjuster for the metering plate arm (aka: the idle mixture screw). It almost looks like the black piece beneath the allen head screw is a home-made cover plate - remove and see what's there.

BOV - what do the ends of the blue hose go to (looks like to a intake manifold port, beneath the throttle body, on the right, but can't see where it goes on the left)? Maybe the other end is attached to an aftermarket BOV (or should be)? Another possibility is that the BOV is attached to the intercooler (obviously, easy to see if it is), but would need a hose that runs from it to a spot below the throttle body.

O2 sensor - I can't tell in the pics if that is a Euro fuel distributor, or a USA one with Lambda assist - looks like it might be Euro due to the graininess of the metal beneath, but would need to know that to give you any idea what the O2 sensor in your car is used for.

I will tak a closer look at that screw the next time I pull the intercooler, thanks!

Check these pics for that missing BOV we were looking for.

on the right bank:


On the left with the blue hose attached.

[DSPTurtle]

That took ballz to do a 930 motor in white. But based on the stickers in the rear deck, this must be a showcar or something.
I think it looks good btw. Oh, and I wouldn't touch the 5mm unless I had a gas analyzer nearby just in case someone did a mod that shortened the screw so that once you turn it you adjust the CO. Normally I'm all for unbolting stuff to figure out how something works, not the mixture screw...

[JFairman]

Those two valves in your post number 8 are old emissions air pump diverter valves.

The painted white fuel head is a rough finish cast iron early non lambda fuel head with the two plugged injector line fittings that were for V8 installations when installed on some other cars like old Mercedes V8's and old Bentley's and Rolls Royce V8 motors with CIS.

[Les Paul]

Just out of curiosity how does the car run?

[Bucketlist]

Originally Posted by Les Paul

Just out of curiosity how does the car run?

I have owned many cars in my day, from Cameros and Mustangs to BMWs.
This is my first experience with a 930 turbo and I would say it is a BEAST
A real Thrill Ride.

As far as the BOV we were looking for where else could it be located?

[Ronnie's.930]

Originally Posted by Hot Euro

As far as the BOV we were looking for where else could it be located?

This is really interesting that there isn't a BOV in plain sight in any of your pictures. I don't know if you are familiar with what they do, but if not, they essentially relive boost pressure from the turbo compressor when the throttle plate is closed (otherwise that pressure "hits a wall" and will stall the compressor fan/wheel potentially causing much damage to the turbo). And with the K-Jet/CIS fuel system, the BOV has to be vented to the intake manifold, beneath the throttle plate, and not to atmosphere or an extremely rich running condition is created.

It seems that there is no way that this was left out of your build considering all of the other nice details (twin plug and so forth).

So is there nothing attached to the custom section of white pipe that extends from the metering assembly elbow down to the turbo compressor intake (on the bottom side that isn't shown in the pics)? And are you sure the BOV isn't attached to the bottom side of the intercooler?

[Bucketlist]

Here are a couple of pictures of what I found under that turbo intake tube.
First a hose comming from the manifold: not BOV I translated the label and it says "Ck Filter Daily" so I don't know what it is unless it is some kind of breather filter.
These pictures are really bad because it is so crowded down in there.



Second It is a black can with a white top put on with a red wing nut and attached to the above hose.



Third I tried to show a tag on the side which is red on black with german print but it didn't come out.



Thanks for your help!

[Bucketlist]

Originally Posted by Hot Euro

On my "new" 1981 SC which has an earlier modified 930/51 twin plug turbo engine I am curious about the fuel mixture adjustment. When I look this up there is always a reference to the 3mm screw next to the fuel distributor. While I had the intercooler off yesterday for another problem I looked for this adjustment screw but didn't find it. I know where the air adjustment screw is and have used it to raise the idle speed.
I don't have a problem at this time but was wondering how the mixture is set if I have a problem in the future.
Here are a couple of pictures:

The 5mm screw in the picture is not holding down a (black) cover, they just painted the area black. (maybe so they could see the screw?)

Question 1: Should I pull the screw and look?

Question 2: Relates to the other problem I am trying to solve. If the metering screw is too tight pushing the plate open, would it make my fuel pump run all the time with the key on and engine off?