Another CIS ???
 

I keep reading about adjusting the 3mm screw on the fuel distributer but I'm confused. The pics I see have a screw but mine looks like the pic below. When I push down on the "plunger" for lack of a better term it opens the plate. It spins but it doesn't seem to do anything. Is this a different version of the same thing?

http://i80.photobucket.com/albums/j177/eq72521/cis.jpg

That's the turbo air meter. The comments you read concerning the the screw are for NA cars on which air flow pushs the meter plate up. The turbos force air into the meter for the top..pushing it down.

Edit: movement of the air plate should translate to movement of the fuel distributor plunger. Fine adjustment of the plunger height changes your idle fuel quantity. Put the fuel distributor on there with the plunger (Be careful you don't drop the plunger on the floor and nick or scratch it) and you'll see what happens. Without system pressure applied to the fuel dist. you won't have much resistance to the air plate movement, but you'll see how it all works together.

That pic is not mine. Mine is still installed in the car. When you say "fine adjustment of the plunger" does that mean just turning it? I ask because I did turn it a little and it didn't feel like it did anything. Does it need to be pushed down while turning or in the upper most position? Why is it that the '78-'79 930 seems to be the least documented 911?

There should be an allen head (female) inside the top of the object you have circled. If you look straight down on it and do not see the allen head it may be sealed with epoxy or wax to prevent tampering.
To adjust your fuel mixture you -gently- push down on the screw head and twist the head very slightly back and forth until you feel an engagement. (It will spin freely until it engages) At that point you insert an allen wrench into the top of the screw and -gently- with reserved pressure, move the engaged assembly counterclockwise (lean). Now you can adjust the mixture using a CO meter. Do not move the setting more than 1/8 turn at a time.

Is that the information you were looking for? Are you having a problem requiring fuel mixture adjustment?

It seems to be running rich based on smell and the condition of the plugs I just replaced, but I don't yet have a CO meter to properly test it. Right now I'm just trying to learn the system. What you're saying is, the "plunger" has a female hex screw inside the larger "barrel" at the top of the "plunger" in the pic, right? When you say "push down on the screw head" are you refering to what I call the "plunger"? If so, does that mean the "plunger" is hollow with a hex screw adjusting the depth of a rod within the "plunger"? Forgive my ignorance of the system and terms but lack of documentation forces me to create my own names.:(

Yes, I am refering to the "plunger".
There are a couple of different designs for this item. My '78 does not have the large "thumb screw" head like the one you have pictured while a friends '78 does have one. Both designs have a female hex head that an "L" shaped allen wrench will fit into. Once you find the hex head and put the allen wrench in it you push the plunger down and rotate slowly from side-to-side until it engages the adjustment mechanism.