how is optimal value for Carburetor adjustment in a volvo 360GL?

I tried to do this with a 'Colortune' but I had no luck - couldn't see the flame.... so I had to do it by listening.... when the engine sounds like its running best, stop turning the screw. Cheers, bogbasic.

The proper home way is using a gas 'anaylser', like Gunson, but they are temperamental and use the thermal properties of the exhaust to compare to air. They are very sensitive to wind and need left to sit for ages to settle depending on how accurate you want it.

Real professional kit uses proper gas sensors.

Most 360s you are looking for around 1.5%. (1% to 2.5% in haynes for B200K)

For older car often bit rich is better, for 240 I have heard setting it around 2.0% would work best.

Anyway few have access to analyzer, in old days even fewer had access to such, so there is method to adjust idle mixture into proper zone without any analyzer.

Hanynes book of Carburettors instruct procedure as follows:

1 Run engine 3000rpm for 30 seconds to clear the manifold of fuel vapours, then allow engine to idle.

2 Use the idle speed adjustment screw to set the correct idle speed at the upper limit of the of the tolerance given in specifications.

3 Remove tamper proof plug and adjust the idle mixture control screw until the highest engine speed is recorded.

Repeat 2&3 until highest highest steady idle speed is reached (using correct idle speed as starting point)

Clear the manifold every 30 seconds during the setting operation by running the engine at 3000rpm for 30 seconds

Screw in idle mixture control screw until the engine speed is reduced by 25rpm

Highest steady idle means that engine runs smooth and not shaking.

With those adjustments it is enough close, will pass mot if there are no other problems, like for example air leaks, which will cause idle to be set wrong, but it is same with gas analyzer, if there are air leaks, no matter how tiny they are, carb will be off, very hard to adjust and very hard to make car run properly, so checking that carb base is not warped and that there are no air leaks is a must before making adjustments.