Dump Valve

Vacuum Hose Routing:

Dump valve has two vacuum lines. The upper one connects to right intake manifold at bottom of throttle body. This supplies a vacuum signal to dump valve and acts on a diaphragm inside valve. While vacuum signal is present, dump valve is held closed to atmosphere. The lower one connects with a tee between vacuum regulator and distributor vacuum unit. When there is sudden throttle opening, vacuum signal disappears in manifold line (upper) and that allows the tee line (lower), to be vented to atmosphere, causing timing to retard and prevents possibility of ignition detonation.