The VVC cylinder head is a separate casting from the non-VVC head, machined to accept the Variable Valve Control mechanism on the inlet side of the engine. It shares the same basic crossflow layout and pent-roof combustion chamber design as the non-VVC head, but adds the bearing supports, oil galleries, and housing interfaces required for the VVC eccentric-disc drive system. VVC heads are fitted only to the MGF VVC, MGF Trophy 160, and MG TF 160, identified by the 18K4K engine number prefix. VVC heads cannot be fitted to non-VVC blocks and vice versa, the timing drive, ECU calibration, and oil supply arrangements are specific to each head type.
Two VVC Head Casting Specifications
The catalogue lists two distinct VVC head castings. LDF108520 fits the MGF VVC (standard specification, not Trophy and not TF 160). LDF000980 fits the MGF Trophy and MG TF 160, reflecting the Trophy/TF 160 engine's revised specification including high-lift camshaft profiles and the induction changes that produce the 160 PS output against the standard VVC's 145 PS.
When ordering a bare head or a head-with-valves assembly for a VVC engine, confirm the model, MGF VVC, MGF Trophy, or MG TF 160, so the correct casting is supplied.
How the VVC Mechanism Works
The VVC system continuously varies the inlet valve duration from approximately 220 degrees at low rpm to 295 degrees at higher engine speeds, valve overlap varies between 21 and 58 degrees across the operating range. This provides strong torque through the mid-range and a significant power advantage at higher rpm, producing a distinctive power curve that climbs steadily without the step-change of cam-switching systems like Honda VTEC. The mechanism uses a pair of eccentric discs, one driving the inlet cams for cylinders 1 and 2, the other driving the inlet cams for cylinders 3 and 4. Because eccentric rotation is non-linear, the discs can accelerate the inlet cams during one part of the cycle and decelerate them during another, effectively changing inlet valve open duration.
The first eccentric disc is driven from the main timing belt (which also drives the exhaust camshaft). The second eccentric disc is driven from the exhaust camshaft via a separate toothed belt at the rear of the engine, so a VVC engine has two timing belts, each requiring replacement at specified intervals. The mechanism is controlled by the MEMS ECU through the VVC hydraulic control unit, which modulates the eccentric disc position using engine oil pressure. Position feedback comes from the camshaft sensor, there is no separate VVC position sensor; the cam sensor reads the VVC drive position, and the ECU uses this to close the control loop.
VVC Mechanism Components
The core VVC service components are catalogued here. The VVC hydraulic control unit (LXS100080) is the electro-hydraulic actuator that modulates the eccentric disc position, a common wear item at high mileage. The VVC valve assembly (LGH101350), individual VVC valves (LGH101300), and VVC valve solenoids (LNN100000, two required) sit within the hydraulic control circuit. Seal kits are available for both the hydraulic control unit (LXB100060) and the VVC valves (LXB100070).
The VVC shaft assembly (LJZ100680) and the inlet camshaft assemblies with their integral VVC housing seals (LJQ100950) complete the mechanism. Signs of VVC mechanism wear include a rattling noise from the rear of the cylinder head, erratic operation of the VVC (loss of high-rpm power, or rough running where the mechanism is stuck in an extreme position), and irregular oil pressure at the VVC feed.
Head Gasket, The HGF2 MLS Kit
The definitive head gasket solution for the VVC K-series is the MGOC Spares HGF2 head gasket and lower rail kit, the VVC equivalent of the Non-VVC HGF1 kit. Originally developed by Land Rover for the K-series in the Freelander application and adapted for VVC by fitment type, the kit includes a multi-layer steel (MLS) gasket (LVB000320), a strengthened lower rail assembly (LCN000140L), a set of ten 10.9-grade through-bolts, and a cam locking tool (Z070). The MLS seal is a metal-to-metal joint that does not degrade in the way the original elastomer gasket could, and the uprated bolts deliver consistent, higher clamping force.
When fitting a lower rail of either type, a new O-ring (CDU2206) sealing the lower rail to the oil pick-up pipe must be fitted, a small detail, but a forgotten O-ring will cause oil pressure loss. All kit components are available separately.
Cylinder Liner Protrusion
Before fitting any head gasket, cylinder liner protrusion must be measured. All four liners must protrude a minimum of 0.1mm above the block face and be within specification of each other. Liners that have sunk below 0.1mm require shimming using dedicated liner shim kits (K Series Cylinder Liner Shim Set ZT403 from the catalogue).