Operation

Switch--located in the air cleaner--controls vacuum to the thermostatic air cleaner, choke vacuum break and distributor vacuum advance--according to engine temperature.

When temperatures are below the calibration value of the switch;
- No vacuum to thermostatic air cleaner
- No vacuum to choke vacuum break--runs richer
- Vacuum advance receives full manifold vacuum.

When temperatures are above the calibration value of the switch;
- Manifold vacuum is directed to the thermostatic air cleaner and choke vacuum break ports
- Vacuum advance port is blocked--preventing distributor advance above the switching point.