Distributor Vacuum Advance Regulator
Number: J81/20Date: October, 1981
Subject: Ignition Vacuum Advance
Models: 1982 XJ6 Series III
A vacuum regulator (see illustration), EAC 4012, has been introduced into the distributor vacuum advance line in order to provide increased ignition advance during closed throttle engine operation.
The regulator limits the vacuum to the distributor when zero vacuum is at the throttle edge port. When the throttle edge port vacuum exceeds a limited value the vacuum regulator allows vacuum direct from the intake manifold to the distributor vacuum unit.
The unit is located in the vacuum lines under the manifold.