V8 Engines
On V8 engines TVS is located in coolant outlet housing and directly controls vacuum. With coolant temperatures below 180°F (82°C), manifold vacuum is applied to actuator which closes EFE valve. This routes hot exhaust gases to base of carburetor. When temperatures reach 180°F (82°C), vacuum to actuator is stopped. This allows a spring to return actuator to its at rest position, opening EFE valve.