Older K&B .61 carb question

[Dr.J]

I was just given an older K&B .61 engine with a square carb on it. The needle valve is the older bent wire type. But there is what seems to be an air bleed (screw with a spring around it) on the oppo side of the carb from the needle valve. There is no idle mixture needle. Does this sound right to anyone?

[MECOA]

does it look like the carb on the left here...

http://www.mecoa.com/faq/carb/kbsq/kbsq.htm

The only one with an air bleed was the very first VECO versions of the engine. An air bleed will always have a visible hole in the side of the carb body that you can see the adjustment screw intersecting to close off the hole.