As has been pointed out numerous times, the correct way to set the mixture on these cars is with a multi meter with a duty cycle. You can find them at Sears for under $30.

There is also technique where you can use the DC voltage setting. Here is a very good article:

http://www.landiss.com/mixture.htm

It is for the later KE injection, but the principles are the same.

If you find that it needs adjustment it's usually a sign that you need a new oxygen sensor.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe