Unitized distributor vacuum spark advance control valve with regulator

Claim 1

A spark timing control for an engine having a carburetor induction passage with a spark port above the idle speed position of the throttle valve, a distributor breaker plate spring biased in a spark timing retarded setting direction, vacuum servo means normally moving the breaker plate in an advanced timing direction as a function of increases in spark port vacuum applied thereto, conduit means connecting the spark port to the servo means, and control means momentarily advancing the timing to a spark setting advanced above that which would normally be called for according to the level of vacuum at the spark port in response to accelerative opening movement of the throttle valve, and subsequently returning the timing to the spark timing setting called for by the spark port pressure Level, the control means comprising a one piece unitary valve body structure having first and second axially aligned valves movable therein between open and closed positions and spring biased to open and closed positions, respectively, the first valve variably controlling communication of pressure between a first line connected to a manifold vacuum reservoir and a first portion of the conduit means connected to the servo means, the second valve controlling communication of pressure between the first portion and a second portion of the conduit means connected to the carburetor spark port, the second valve having means providing at all times a slow bleed down of pressure between the servo means and the spark port while being movable to an open position in response to spark port pressure above the force of the spring means and the servo means pressure, means connecting manifold vacuum to act on the first valve in opposition to the spring means whereby steady state and light acceleration engine operation vacuum levels connects the first and second portions while disconnecting the vacuum reservoir from the first portion so that changes in carburetor spark port vacuum level cause a corresponding change in the spark timing, and whereby heavy accelerations reducing manifold vacuum to a low level connect the reservoir vacuum to the servo means to temporarily advance the timing beyond the setting called for by spark port pressure level until the servo means vacuum is bled to the spark port level, and other means axially aligned with and acting on the first valve to limit reservoir vacuum and thereby the temporary advance and responsive to manifold vacuum levels above a predetermined level indicative of engine deceleration conditions for moving the first valve to temporarily connect reservoir vacuum to the servo means to decay the reservoir vacuum to the servo means pressure level.