Internal combustion engine ignition spark vacuum advance system

Claim 1

An internal combustion engine ignition spark vacuum advance system for motor vehicles comprising in combination with a carburetor having a spark advance port, an ignition distributor having an ignition spark advance mechanism operated by a spark advance vacuum unit having a vacuum port and a source of direct current potential, a vacuum line extending between said carburetor spark advance port and said spark advance vacuum unit vacuum port, a two-way valve having an operating coil included in said vacuum line which is normally in a first condition to establish a vacuum connection between said carburetor spark advance port and said spark advance vacuum unit vacuum port and operable, upon the energization of said operating coil, to a second condition to vent said vacuum advance unit vacuum port to atmosphere, a first temperature sensitive switch having normally open contacts which are operative to the electrical circuit closed condition by in-vehicle temperatures greater than a selected magnitude, a second temperature sensitive switch having normally open contacts which are operated to the electrical circuit closed condition by engine temperatures greater than a selected magnitude, the speed sensitive switch having contacts which are operated to the electrical circuit closed condition in response to vehicle speeds of less than a selected magnitude and, means for connecting said operating coil of said two-way valve, said contacts of said speed sensitive switch and the parallel combination of said normally open contacts of said first and second temperature sensitive switches in series across said source of direct current potential, whereby engine spark advance is provided with in-vehicle and engine temperatures less than respective predetermined normal valves at cranking speed.