V8 Engines

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