Is there only one screw for idle adjustment on these carbs ??
Allen

The idle adjustment should be done by a screw on the throttle butterfly of each carby.

High idle adjustment is done by a screw on the choke mechanism on each carby.

The richness is adjusted by lowering or raising the jet and it will change the idle speed as well.

Worn throttle spindles, faulty PCV system or vacuum leaks can also effect idle.

thanks gotto the carbies have been reconditioned I have not had to touch them for 9 months .engine slowly stops at idle, usually at traffic lights
Allen

If the idle is low then i would start by checking the sucking sound down each throat. I use a piece of vacuum hose. Just stick one end in your ear and the other in the carby intake. If one carby is sucking louder then just open the throttle slightly on the quieter one. They should sound the same. If they already sound the same then open them evenly. It might pay to check the mixtures while your at it.

Of get hold of a Carbi synchroniser if your hearing ain't so good. But agree completely.

SU carbs have a tendency to not like idling - maybe something to do with being a variable jet design that reacts to slight changes in air and fuel flow, especially when the temperature changes.

This is what Stibbsy means if you aren't aware.
I've been using one for a long time and is very helpful on the occasions when the hose method doesn't give a clear signal.

If one carb is taking less air than the other, you can open it slightly to be the same as the other, without having to reset the throttle interlocking bar that joins the 2 spindles.