Running rich (continued)

[jagman1970]

Had car in for MOT this morning (it passed) and whilst there the tester checked the exhaust emissions when I mentioned the problems I'm having. I know it's not necessary but he did it as a favour.
Well at 2500 revs it read 5.6% (a little high) but at tick over it read 8.3% (very high). So how is the mixture adjusted at tick over. the float levels have been checked and they at correct. The balance has been checked and set up using a flow meter. The needles are the correct type. The jets have been adjusted using the method as per the manual and then finely adjusted using a digital depth gauge. Fuel pump is same as last year when the car ran ok. Where do I go from here?
Thanks for any advice.
PS Triple SU's

[Heuer]

Lean out the mixture at idle by half a turn on each carb. Then use the piston lifts to see how the idle changes - should increase for a second or two and drop back. On the SU's the mixture is set at idle.

[abowie]

In my experience one turn is almost exactly 5% CO at idle. You want about 5% CO at idle, so David's half turn is probably spot on.
The one tricky thing with 3 SU's going into 2 pipes is being sure you have the centre carb set correctly.
Go on, buy yourself a Gunson CO meter. It takes all the guesswork out of it.