Ok Now that I have your attention can any body confirm that
1)The cover screw to the ALDA is covered with black plastic if has never been touched?
2)If true If I want to touch it what is the best way to open it for the first time(heee heee)
3)Will touching it make me blind? oops wrong forum!
4)Can I do bad harm to my 84 300 sd by just tweaking it a little?
5)Beware the spring breaking I know all ready.
6)there is an alloy shroud around the black plastic how will I get to the lock nut.
7) or do I just leave well enough alone and don't fix it if it ain't broken.
thanks all in advance!
Pete.
300sd 84 79k

If it ain't broke I definitely wouldn't fix it. But for those that can't get off the line (this should not be adjusted unless the car has a problem off the line. Plenty of reasons for lack of power elsewhere. Off the line there is no boost and lack of fuel delivery is less of an effect here.

There is danger to making the adjustment as occasionally something comes apart inside and the car will then go nowhere.

Peel back the metal shield in small sections till you can remove the plastic insert. Break the pieces from under the locknut before you loosen it.

And after all that, be advised that this is not considered a service shop job. It is only supposed to be adjusted on a pump calibration bench.

Good Luck