FIE
POWER ENRICHMENT SYSTEM
4. POWER ENRICHMENT SYSTEM
The power enrichment system remains basically unchanged. This system furnishes the enriched mixture needed for efficient performance during high power operation. Manifold vacuum, which is strongest at the idle, decreases as the load on the engine is increased. The power enrichment system is operated by this decreased manifold vacuum. If there is a strong manifold vacuum, it acts on the economizer diaphragm to keep the power valve closed. When manifold vacuum is reduced below a certain point, the power valve is opened, enriching the mixture.
The illustration for the power enrichment system also shows the secondary metering system. It is to be emphasized that there is no physical connection between the two systems. The secondary metering system is controlled by
the secondary throttle plate position. That, in turn, is controlled solely by primary venturi vacuum.
5. SECONDARY SYSTEM
The secondary throttle plates in the 1954 applications of this carburetor are controlled by a vacuum-operated diaphragm. Vacuum to operate the diaphragm is taken from a primary venturi. Under high speed and power conditions this vacuum will act to open the secondary throttle plates. The diaphragm spring will move the secondary throttle plates toward the closed position when the vacuum is reduced with a reduction in engine speed.
At idle and at lower speeds, the secondary throttle plates are closed. As the primary throttle