Impala V8-305 5.0L VIN H 4-bbl (1982)
Distributor Thermal Vacuum Switch: Description and Operation
Distributor Spark Thermal Vacuum Switch (DS-TVS)
When engine coolant temperature is below the calibration temperature the switch allows no vacuum flow to the distributor.
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.