The MGOC Spares range includes reconditioned exchange engines for the MGC, remanufactured by specialist engine builders with over 75 years of experience. Standard reconditioned engines are supplied as lead-free units, built to tighter tolerances and finer surface finishes than were achievable at the original factory, with every engine validated in purpose-built test cells prior to despatch. Each engine is converted to run on either unleaded or leaded fuel. Two standard exchange engines are available: one for manual gearbox cars (exchange unit 68G347LF) and one for automatic gearbox cars (exchange unit 68G355LF), both based on the 29G engine series.
What the Rebuild Involves
A standard reconditioned C-series engine is stripped, cleaned, and inspected before machining. The seven main bearing crankshaft is reground to the appropriate undersize, with matching main and big end bearing shells. Six new pistons and rings are fitted to honed or relined bores. The cylinder head is skimmed, fitted with new valve guides, valves, and springs, and converted to hardened exhaust valve seats for unleaded compatibility.
The camshaft is reground or replaced with new cam followers; the timing chain, tensioner, and damper are renewed; the oil pump is rebuilt or replaced; and all gaskets, seals, and core plugs are renewed throughout. The complete rotating assembly is balanced to reduce vibration and extend bearing life. Each engine is run on a test bed to verify oil pressure, compression, and freedom from leaks before despatch.
Stage 2 Performance Engines
The Club Stage 2 engine is a comprehensive performance build that goes well beyond a standard recondition. Stage 2 engines include an engine backplate, a modified camshaft with revised valve timing for improved mid-range torque and top-end power, a gas-flowed cylinder head with enlarged and polished ports, a balanced rotating assembly (flywheel, clutch, pistons, connecting rods, and crankshaft), vernier duplex timing gears for precise cam timing adjustment, and a choice of increased capacities. Balancing the complete rotating assembly ensures smooth operation at higher engine speeds and eliminates the vibration of an unbalanced unit. The C-series responds well to careful tuning, the long-stroke design produces excellent torque, and individual inlet and exhaust ports give better flow potential than the siamesed ports of the B-series.
Stage 2 engines are guaranteed for twelve months with unlimited mileage, and detailed specification sheets are available on request.
Core Unit Requirements
All standard reconditioned engines are supplied less ancillaries, without flywheel, starter motor, distributor, or manifolds. The customer's old engine is returned as the core unit for reconditioning. In some instances, due to a lack of serviceable core units, customers may be asked to provide their own engine for reconditioning rather than receiving an exchange unit. This is particularly relevant for 29GA (USA and later Canadian) and 29GB (French market) units, where core availability is more limited than for the standard 29G series.
With fewer than 9,000 MGCs built in total, and the 29GB series accounting for only around 244 engines, the pool of rebuildable cores is finite and diminishing. Owners of North American or French-specification cars should contact MGOC Spares to discuss availability and lead times before planning a rebuild around an exchange engine.
Installation Considerations
When fitting a reconditioned engine, all ancillary components should be inspected and renewed where necessary rather than transferring worn items from the old unit. Engine mountings, cooling hoses, the fan belt, oil cooler hoses, and the clutch assembly should all be addressed at the same time. The cooling system should be flushed and refilled with fresh coolant, and running-in oil used for the first fill, switching to the appropriate Castrol Classic grade after the first 500 miles.
Engine Number Plates
Blank engine number plates and drive screws are available for engines being rebuilt, allowing correct identification to be maintained or restored after reconditioning. Two drive screws secure each plate to the engine block. Maintaining accurate engine identification is important for the car's history and for future parts ordering, the engine prefix determines which ancillaries, carburettor specification, and crankcase breathing system are correct for the unit fitted.