Dodge Colt/Challenger/Conquest/Vista 1971-1989 Repair Guide

Orifice Spark Advance Control



This is used on 1977 models only.

The OSAC valve is located in the vacuum line between the distributor and the carburetor. Its function is to delay vacuum advance during medium to high speed operation, when high vacuum would be present. It is used only with the single diaphragm distributor.