Ignition Changeover

Vacuum chamber for ignition retard is connected directly to carburetor and is controlled by throttle. Vacuum ignition retard is only effective during acceleration. Vacuum chamber for ignition advance, which overpowers ignition retard chamber, will be activated by switch-over valve whenever the following conditions are met: Oil temperature below 77°F will close temperature switch and deactivate switch-over valve. With oil temperature above 77°F and engine speed over 2000 RPM, RPM switch is closed, deactivating switch-over valve.