Exhaust Emission Systems - BMW: Description

BMW engine modification system consists of:

1. A specially calibrated intake manifold which properly distributes air/fuel mixture to each cylinder.
2. A carburetor with reduced flow curve permitting optimum performance with a leaner air/fuel mixture.
3. A distributor incorporating a dual acting vacuum unit.
4. A vacuum unit which controls throttle position during periods of deceleration.
5. A control valve which governs operation of throttle vacuum unit.
6. An RPM switch which activates control valve.
7. A thermostatically controlled air cleaner.
   Fig 1: Distributor Dual Acting Vacuum Unit

   Courtesy of BMW OF NORTH AMERICA, INC.