The non-VVC K-series cylinder head is a crossflow all-aluminium DOHC 16-valve casting used on every MGF 1.8i, MGF 1.6i, TF 115, TF 120 Stepspeed, and TF 135. A single toothed timing belt drives both the inlet and exhaust camshafts directly, and the camshafts operate sixteen valves via direct-acting hydraulic bucket tappets. The combustion chambers are a pent-roof design with centrally-located spark plugs accessed from the top of the head. In the MGF/TF mid-engine layout, the engine sits transversely with the inlet ports facing the rear of the car and the exhaust ports facing the rear bumper, the reverse of how the same engine is mounted in the front-engined Rover 200/25/45.
Cylinder Head Assemblies, Timing Belt Width Matters
Three complete cylinder head assembly specifications are catalogued. MGF 1.8 and the very earliest 1.6 cars used a 23mm wide non-auto-tension timing belt and a head matched to that specification. The vast majority of cars, all MGF 1.8 and most 1.6, use the 26mm wide auto-tension timing belt and a correspondingly revised head. Both are available new (where applicable) or as reconditioned exchange units.
Early 23mm engines can be upgraded to the 26mm auto-tension head, but the timing belt and tensioner must be replaced to the auto-tension type at the same time. On the very earliest 1.6 non-auto-tension engines, the crank pulley and crank gear may also require changing to match. Before ordering a head assembly, confirm whether the existing car has the 23mm or 26mm timing belt fitted.
Inlet Camshaft, Three Specifications by Engine Number
The non-VVC inlet camshaft has three distinct specifications across MGF and TF 1.8 manual production, plus a separate specification for the 1.6 and the 1.8 automatic. The early MGF 1.8 manual cam (LGC105990) fits engines up to J31 694354 / J32 692084.
The later MGF 1.8 manual cam (LGC106960) fits engines from J31 694355 / J32 692085 onwards, and is also fitted to the MG TF 1800 automatic. The TF 135 ‘high-lift’ cam (LGC000280) is specific to the MG TF 1800 manual and is a major contributor to the TF 135's power output of 136 PS against the MGF 1.8i's 120 PS. A separate cam (LGC106950) is used for the MGF 1.8 automatic and all MGF and MG TF 1.6 manual engines. An important ordering note: the earlier LGC105990 cam was supplied complete with the distributor drive spindle bush (NJJ10001) and roll pin (PA112150), but the later LGC106960 cam is supplied without these components, when replacing an early cam with the later item, the bush and roll pin must be ordered separately.
The TF 135 high-lift cam must be paired with the correct TF 135 ECU calibration, fitting it to an earlier MGF engine without corresponding ECU changes will not deliver the intended power gain and may cause poor running.
Exhaust Camshaft, Three Specifications by Engine Number
The exhaust camshaft also went through three specifications on the 1.8 manual. The earliest cam (LGC10205) fits engines up to J31 196826 / J32 197073.
The second (LGC106010) fits from J31 196826 / J32 197073 up to J31 694354 / J32 692084. The third (LGC106950) fits from J31 694355 / J32 692085 onwards, this is the same part number as the 1.8 automatic and 1.6 manual exhaust cam. The TF 135 high-lift exhaust cam (LGC000280, same part number as its inlet) is paired with the TF 135 inlet cam and completes the TF 135's camshaft package. Engine number is the definitive reference for which exhaust cam is correct.
Camshaft Oil Seal Changes, Colour-Coded Front and Rear
Early MGF 1.8 manual engines to J31 694354 / J32 692084 used a single seal type (LUC10012) at both front and rear positions. From J31 694355 / J32 692085 onwards, covering all MG TF manual, all 1.8 automatic, and all 1.6 manual, the seals are colour-coded and orientation-specific: a black seal (LUC100290) at the front and a red seal (LUC100220) at the rear.
The early single-type seals can be replaced by the later colour-coded pair, provided the correct front/rear orientation is followed. Fitting the seals the wrong way round will cause oil leaks at the camshaft ends.
Cam Carrier Cover and Breather Hose Pairing
The camshaft carrier cover (rocker cover) changed at engine number J31 590355 / J32 568018. The early cover (LDR101980) was superseded by the later LDR103260 (MG TF 1800 manual, MGF and MG TF 1600 manual). MGF and MG TF 1.8 automatic cars use a different cover again (LDR104511).
When replacing an early cover with the later LDR103260 item, both the manifold breather hose (LLH102380) and the throttle body breather hose (LLH102390) must also be changed to match, the breather routing differs between early and late specifications, and mixing parts will result in vacuum leaks or the hose not connecting to its port. The cover is sealed to the head by a single gasket (ZUA000170) and secured by fifteen bolts. A yellow oil filler cap with seal (LQC100270) fits on top of the cover.