This is for an SA22. I think nipple "b" in the attached picture connects to the Altitude compensator.

Please confirm. But, what does the big nipple between the two oil injection nipples connect to?

Herb

 

You are correct: nipple B connects to the Altitude Compensator via a fairly short and stiff hose that's a bit of a pain to get on without snapping the AC's nipple. Eaiest to slide it on while lowering the carb into place.

Nipple A is the connection forthe cold-start assist antifreeze bottle, over on the right rear fender. Cali cars like mine never had it - my carb has a brass plug there instead.