Distributor Spark Thermal Vacuum Switch (DS-TVS)

This switch allows no vacuum flow to the distributor when engine coolant temperature is below the calibration temperature. When engine coolant temperature is above the calibration temperature, the DS-TVS allows ported vacuum to the distributor. The ported vacuum signal is controlled by a distributor spark vacuum delay valve (DS-VDV) which maintains vacuum advance during rapid throttle openings, thereby improving engine response during cold engine operation.