air fuel mixture

[rdssdi]

I have a federal +2 with twin Zenith Stromberg carbs. The metering needles are spring loaded.

Are these needles adjustable? How is that accomplished. I do not think it has the ability to be adjusted from the top of the carb through the piston assembly.

The needles will move in and out of the piston. I can adjust that way using the set screw to hold the needle at the proper height. This is tricky as I do not have a way to accurately measure the protrusion of the mixture needle from the piston.


Suggestions?

Bob

[rdssdi]

The workshop manual states that the metering needle / air fuel mixture is not adjustable. It says the needle should be set into the piston with the needle shoulder flush with the piston face.

My metering needles were set slightly recessed into the piston. As the engine was running lean I set the metering needles fully into the piston. It appears that the engine is now running rich.

Is it a factor of emissions regulation which makes these non adjustable?

Bob