Emissions on my Slant

The distributer has to advance mechanisms.

One is the mechanical advance, it advances the engine spark timing as the engine rpm increases.

The other is vacuume advance, the vacuume advance is based on engine load.

When the throttle blades are closed at idle, there is no vacuume and no advance. As the blades open there is more vacuume and the advance increases.




Also as the load on the engine increases, think going up a long hill, the vacuume produced is different and the advance changed to accommodate that.