Engine (Ignition System)

Every 3000 miles (4800km) the distributor needs lubricating. The cam should receive the slightest smear of grease, and the rotor-arm should be removed and a few drops of light oil applied (for the shaft bearing). Similar oil should also be applied through the hole in the baseplate to lubricate the centrifugal weight mechanism. A tiny amount of grease or engine oil should be applied to the contact breaker pivot. Every 6000 miles (9600km) the contact breaker should be checked and cleaned if necessary (with an extremely fine abrasive and then washed in petrol). The contact breaker gap should be set to 0.012 inch (0.3mm) with the contacts fully open. The toolkit's screwdriver comes with a suitable feeler gauge. If you have the full toolkit in your car, then you are very lucky!

The static timing is 20 degrees before top-dead-centre. If the engine has been uprated with higher compression pistons (which is very likely now), then changes to the timing, both static and dynamic, are desired. This is explained in some detail in Leo Archibald's book "AC 2 Litre Saloons and Buckland Sports Cars" (Veloce - 2002).

The surfaces of the high-tension leads, distributor-cap and the top of the coil should be kept clean, especially when the weather is turning damp and cool. In particular, the spark-plug leads are bundled together into a tube, where dirt can accumulate. These can be cleaned using WD-40, but this should not be sprayed directly onto the ignition parts themselves, because it is a good insulator and so it should be kept away from any connectors and contacts.

Spark-plugs are specified in the manuals as Lodge C14, 14mm. The gap is specified as 0.015 to 0.018 inch (0.38 to 0.46mm). When low octane 2 star petrol was phased out in the UK (in 1989), I found that slight mis-firing occurred on partial throttle, and I followed advice of another classic car owner to widen the spark-plug gap. With a gap of about 0.025 inch (0.64mm) the trouble was solved.

Engine (Dynamo)

The dynamo is gear driven, and is mounted transversely on the right-hand side of the engine near the flywheel. Every 1000 miles (1600km) add a few drops of engine oil to the dynamo bearing via the lubricator. Every 12000 miles (19200km), remove the felt pad from the lubricator and half fill with petroleum jelly. Also at this service interval, the brushes and commutator should checked. These can be seen after removing the metal band from the outer end of the dynamo. The spring-loaded carbon brushes should slide easily in their holders, but can be cleaned with a tiny amount of petrol on a cloth if necessary. The same cleaning process can be done to the commutator (i.e. the copper segments that the brushes run against) while cranking the engine over. The starter motor should receive similar attention. If brushes have to be replaced, then they need bedding in before the dynamo or motor can be used.

Battery

Car batteries have changed somewhat since the 1940s! The old maintenance procedure specified checking/topping up (with distilled water) the cells, every 1000 miles (1600km). Battery terminals should be smeared with petroleum jelly. Occasionally, check the state of charge of each cell using a hydrometer to test the specific gravity of the electrolyte. Readings of 1.28 to 1.30 would indicate a fully charged cell, in mild weather. Readings will be lower in cold weather.

Cylinder-Head

A new head gasket is recommended whenever the cylinder-head is refitted. Unfortunately, these gaskets are expensive! The head is very heavy, so remove exhaust, carbs etc. The timing wheel needs to be removed and that has its own perch to rest on. I found it easiest to stand astride the engine, lift up the head and rest it on the wing (wing protected by cloths and a plank of wood). If the head is stuck to the block, then refit the timing wheel and crank the engine over to use the compression to break the seal.

In the block's water jacket, you may find that debris has almost buried the rear two cylinders. This is a laticework of debris that accumulates because the water flow is stagnent in that rear area. Check carefully the condition of the top surface of the alloy block, as a perfect joint is required. Corrosion or old repairs may cause trouble. Also check that the liner top flanges are all level with each other. These flanges should be higher than the surrounding block, typically by 10 to 12 thou (although some people prefer a greater height). Also check how flat the mating surface of the head is. Not forgetting the condition of the cylinder-head studs, as these may corrode near the water passages through the gasket towards the rear.

When refitting the cylinder-head, AC recommended a gasket sealant. Also make sure that the gasket is the right way up so that the water passages line up with those in the head. As the head is lowered into place, the top of the chain tensioner needs to be pushed inside the rear of the head, so that it is not trapped underneath. The tightening sequence of the 14 head nuts, is to start from the centre pair and work your way outwards, but leaving the 4 longer studs until last. Some heads have all studs equal in length, so the final 4 to tighten are either side of the centre pair. The torque setting is 40 ft-lbs, and they should be retightened after the engine has run and warmed up and again after 100 miles running. The timing wheel has offset driving studs to ensure that it goes back onto the camshaft the right way.

Tappet clearance is 0.020" when hot.

Be sure not to try running the engine without the rocker-cover in place, because there is an oil jet supply to the timing chain which will spray out if not covered.

Torque Settings for Engine Bolt/Nut Tightening

Cylinder-head: 40 ft-lbs

Big-end bolts: 25 ft-lbs

Main bearing caps: 40 ft-lbs

Flywheel: 28 ft-lbs.

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