Black smoke on idle

[sega]

Today i found a really nice phase 1 black gtt in my driveway. The owner has some isues with the car since the carb had been rebuild by a french company. It looks like a good job apart from the black smoke on idle and when you hit the throttle its running very rich. It has the restrictor in the breather hose. When you turn the idle mixture screw nothing happens.
My plan was to check for leaks wich i doubt looking at the great condition of the car.
Also look at the idle valve.
Did i forget something before i pull the carb of if this doesnt work?

[Brigsy]

I would take it off and check the jetting and generally check the carb is together properly.

[sega]

Car is running ok now. But wil post my findings so maby it can help somebody in the future.
Idle mixture screw was broken. The black smoke was caused by a to large brass Washer under the idle jet brass screw. I replaced it with a oe one and the smoke was gone.