The C-series crankshaft runs in seven main bearings, a substantial increase over the four-bearing crankshaft of the earlier Austin-Healey 3000. Fourteen cap screws secure the bearing caps. Separate exchange crankshafts are available for manual and automatic gearbox cars, reconditioned on a customer's own unit basis: the two differ at the rear, where the manual crankshaft carries a spigot bush to locate the gearbox input shaft and the automatic uses a different bush suited to the torque converter drive. The crankshaft pulley with integral vibration damper differs between 29G and 29GA engines.
Main and big end bearing sets are each available in standard and four oversize grades, with thrust washer sets in standard and oversize to control crankshaft end-float. When ordering, the required size must be stated, determined from the journals after regrinding, or from the size stamped on the existing shells.
Pistons, Rings, and Cylinder Liners
A complete set of six pistons covers the standard 2,912cc engine. Piston ring sets are available in standard and four oversize grades (plus 20, 30, 40, and 60 thousandths of an inch). Six individual cylinder liners are available for reboring. Piston and ring sets for the French-market 2,850cc (29GB) engine are typically made to order, enquire before planning a rebuild around them.
Connecting Rods
Reconditioned connecting rod assemblies are available on a customer's own unit basis, supplied with new small end bushes. Each engine requires six rods with twelve bolts and twelve nuts. Reconditioning involves regrinding the big end bore and fitting a new small end bush, restoring the rod to the correct tolerance for the crankshaft journal size.
Flywheel, Ring Gear, and Drive Plate
The manual gearbox flywheel and ring gear assembly is available on an exchange basis, with the customer's own unit reconditioned. A separate ring gear is available for replacement on an existing flywheel, this is pressed on hot, and ring gear replacement is a specialist task. Three clutch-to-flywheel dowels locate the clutch cover, and six screws with a locktab secure the flywheel to the crankshaft. For automatic gearbox cars, the drive plate (flexplate) assembly has become very scarce, along with its ring gear and fixings, owners requiring these components should contact MGOC Spares, who will strive to source them.
Oil Pump and Pressure Relief
The C-series oil pump is mounted at the rear of the engine. A repair kit is available. Two different securing methods were used: an early stud-type and a later bolt-type.
The later-type bolt is no longer available, but the early stud-type fixing may be used instead. Three bolts with spring washers secure the oil strainer. The oil pressure relief valve was revised from engine numbers 29G/2756, 29GA/357, and 29GB/171.
Sump, Dipstick, and Block Sealing
The sump is secured by twenty-one screws with shakeproof washers around the sides and four nuts with spring washers at the front, sealed by a sump gasket; the drain plug uses a sealing washer. The dipstick assembly carries a rubber washer and a plain washer at the tube entry point in the block. A cylinder block drain plug (or optional drain tap with shimming washers) drains the block. Welch plugs in two sizes (1?-inch and 15/16-inch) seal the casting core holes, inspect for corrosion and replace at any sign of weeping, as a failed plug causes sudden total coolant loss.
Camshaft, Followers, and Timing Chain
The camshaft is available on a reground exchange basis, with the customer's own unit reconditioned. A complete set of camshaft bearings is available for refitting. Three screws with spring washers secure the cam locating plate. The distributor housing gasket, screws, spring washers, and a distributor gear Woodruff key service the distributor drive from the camshaft. Twelve cam followers (tappets) and twelve pushrods complete the valve train between the camshaft and the rocker assembly.
The timing chain drives the camshaft from the crankshaft via sprockets. A hydraulic chain tensioner maintains correct chain tension, while a separate chain damper reduces noise and wear. The timing cover is sealed by a gasket and secured by five long bolts and two short bolts with spring washers, with an oil seal surrounding the crankshaft nose. Timing chain stretch is a common issue on high-mileage C-series engines, causing retarded valve timing and reduced performance, the chain, tensioner, and damper should all be replaced together as a set during any major engine overhaul.