Altitude Compensator

Air density becomes thinner at higher altitudes. Therefore, the carburetor produces too rich an air/fuel mixture at higher altitudes. The altitude compensator automatically corrects air/fuel ratio to an optimum mixture.
When vehicle is operated in a high altitude environment, the bellows in the compensator extends, causing the lever attached to the bellows to push up the needle. When the needle is pushed up the air passage becomes wider, allowing larger amounts of air to flow from the altitude compensator to the carburetor, thereby thinning the air/fuel mixture.