Idle Trim Screw - setting?

[Rod1883]

Whilst the car was with Paul near Alton last week for the new Steering Rack, Paul commented on the lumpy idle that to be fair the car has always had. He tweaked the needle adjusters a little to richen it up and that has helped a little.
Digging further on here and elsewhere I've found information regarding the Idle Trim screw located beside the plastic cover which I understand is the temperature compensating mechanism. There seems to be conflicting information on how this screw should be set - I've found info that says this screw should be fully wound in and seated (hand tight only) to ensure maximum enrichment during idle, and other comments that it should be fully open, or backed off ~3/4 of a turn from closed.
I've found mine are pretty much fully open and so I'm wondering if that is my issue.
Has anyone any advice on the setting of this screw?

Thanks

[sujitroy]

There is a separate idle trim screw on the side. I've been told to close it off. The compensators open and close depending on temperature. they can be adjusted using a bowl of hot water.

[trunt]

I believe the idea was that it left the factory slightly open and as the engine freed up it was closed.. The range of adjustment is minimal and apparently only detectible with gas analyzer instruments.

From the Emissions manual..

Trimming Screw Adjustment
Having checked all settings, couple up on air/fuel ratio meter and observe combustion efficiency.
If the readings are slightly outside the permitted limits, adjust both carburetter trim screws by
equal amounts until the needle reads within limits.

NOTE: The trim screw is not an ordinary mixture adjusting screw. The adjustment is so fine
that only with the use of a meter can the results be detected.

[Rod1883]

Thanks
The comments agree with most of the ones I've found elsewhere - the screws should be closed up, although as I said above there are some contrary views.
Quoting from a Jaguar document - '..a new and very stiff engine will require more air than one that has become free' , '..the trim screw my be adjusted to provide a slightly leaner mixture for any engine found to be stiff' , and '.when fully seated, the maximum enrichment is achieved'.
I agree that this screw is not general mixture adjusting, merely for idle.
I think I will close up and back off ~1/4 to 1/2 of a turn so they don't stick.....

[richardthestag]

wind it right in, i.e. closed.

lumpy at idle could be a number of things from fuel pressure being over 3psi max to damned poppet valves on the throttle butterfly and loads of stuff in between. check for air leaks around the carb mounts also