System Components (page 2 of 2)

ENGINE MANAGEMENT SYSTEM – V8

18-2-44 DESCRIPTION AND OPERATION

Control Solenoid and Check Valve

A  = Advance

B  = Retard

C  = Vent

The VCC solenoid is a two wire, pulse width modulated, oil pressure control valve. The valve has four ports;

1 Input Supply Port, Engine Oil Pressure 
2 Output Retard Port, to rear of piston/helical gear (retarded camshaft position)
3 Output Advance Port , to front of piston/helical gear (advanced camshaft position) 
4 Vent released oil pressure.

A check valve is positioned forward of the solenoid in the cylinder head oil gallery. The check valve maintains an oil 
supply in the VCC transmission and oil circuits after the engine is turned off. This prevents the possibility of piston 
movement (noise) within the VCC transmission system on the next engine start.

VCC Transmission
The primary and secondary timing chain sprockets are integrated with the VCC transmission. The transmission is a 
self contained unit.

The adjustment of the camshaft occurs inside the transmission, controlled oil pressure then moves the piston axially.

The helical gear cut of the piston acts on the helical gears on the inside surface of the transmission and rotates the 
camshaft to the specific advanced or retarded angle position.

Three electrical pin contacts are located on the front surface to verify the default maximum retard position using an 
ohmmeter. This is required during assembly and adjustment. (see service notes further on).

Oil Distribution Flanges:
The oil distribution flanges are bolted to the front surface of each cylinder head. They provide a mounting location for 
the VCC solenoids as well as the advance-retard oil ports from the solenoids to the intake camshafts.

M18 0812A

A

B

C