Starting Procedures
Starting an engine like this involves switching the Bryce Berger injection pump to excess fuel mode and lifting the decompressor (this held exhaust valve open) to allow the engine to turn over without compression. The engine is then turned over at a steady pace until 10/15 clicks from the injector are heard; these clicks are a result of the spring & needle of the injector jumping with each injection of diesel at a relatively slow speed as the engine may only be doing 60-70 rpm. This now means there are 10/15 injections of diesel sitting in the combustion bowl on top of the piston. The engine is then turned over much faster, and when the engine had lots of momentum the decompressor is flung down; this means on the next compression stage the pressure in the cylinder becomes so great that the temperature rises to a point that the diesel bursts into flames. Once the first combustion cycle has taken place this gives the engine more momentum until it is over-revving, at which point the excess fuel lever automatically drops off and the engine sits at its governed idle speed.
The smallest A-range models such as the AA1 were available with rope start - a sheave was attached to the flywheel and the engine started by pulling on a rope wound round the sheave. This requires a particular technique to obtain the "clicks" from the injector and prime the combustion chamber with fuel. The decompressor is not used; the engine is rotated to just after top dead centre (TDC) on the intake stroke, then the starter rope is pulled with a nicely judged amount of force calculated to give the engine just enough momentum to raise the piston against compression pressure to the point where the injector operates, at around 20 degrees before TDC, but not so much that the engine carries on past TDC. Instead the compression pressure takes over and reverses the rotation, turning the engine backwards to its starting point and rewinding the rope onto the sheave; effectively the engine is "bounced" off the compression pressure. This is repeated several times until a sufficient number of priming injections have been made; then the starting rope is given a mighty heave sufficient to carry the engine over compression and hopefully cause it to fire. If the heave is not sufficiently vigorous the engine will not fire and the whole process has to be repeated from the start. The method requires considerable amounts of both strength and skill.
When the A Series units are in a generally good state of repair, with compression in the correct range, starting can be relatively painless. The 1960-70's AB1 I own presently starts very easily on the first or second pull every time when primed with engine oil in the in built priming orifice as per instructions. A previous AC1 driving a 4kVA generator I purchased cheaply proved almost impossible to start initially, but the problem was traced to both a broken piston land (probably from intensive work and Easy Start (Ether) use, as it had been a workman's type unit), and the Injector only bleeding-opening at high rpm. Once solved she started and ran very well indeed, despite being 30+ years old, with no smoke.
All Lister single cylinder air cooled units have a 'running' compression ratio of about 15-16:1 to keep stresses on the piston, big end bearing, and connecting rod within reason. To start easily (especially in lower temperatures) all Diesels need around 18-19:1, so the engine may be "primed", according to the operating instructions, using 1-2 'shots' (approx. 5ml) of engine oil injected into the intake duct via a tapping provided for the purpose. This temporarily boosts the compression ratio for the first 2-6 firing strokes, the effect dropping down quickly as the oil is burnt off. Without priming the user is attempting to achieve the same result using tiny amounts of less-viscous injected non-combusted Diesel fuel, which of course takes many revolutions of hand-cranking to accumulate a sufficient amount, with associated frustration and effort. Needless to say, if the engines were unusable at time of purchase, new owners would demand refunds, so obviously they were reliable units when made to be so successful in many lands around the world.
Few electric start models - Lister-Petter, Yanmar, or Chinese types - need any additional starting devices as 1-2 seconds cranking injects enough unburnt Diesel into the combustion space above the piston to boost the compression automatically and quickly.
Some engines are equipped with a "cold starting aid" comprising a pipette incorporated into the oil dipstick which allows a few ml of lubricating oil to be taken from the crankcase, and a removable plug through which this oil can be injected into the inlet manifold. This aids starting in three ways: the oil improves the low-speed sealing ability of the piston rings and valves - especially in a worn engine - thereby ensuring that maximum compression pressure and hence temperature is achieved; the volume of oil injected is a significant fraction of the combustion chamber volume, so the volume at TDC is reduced and the compression ratio increased; and lubricating oil has a lower ignition temperature than diesel fuel, so less extreme conditions are required for the first combustion event.
Electric starting was an option for most of these engines except the smallest A-range models. Electric start models were fitted with a starter motor and a flywheel generator - a set of magnets embedded in the flywheel which induced current in a set of coils in the flywheel housing - to recharge the starting battery. It was never a very popular option. The cost of the engine was significantly more than the hand-start models; the starter motor and the large lead-acid battery added significant extra weight; the flywheel generator was not very effective, and flat batteries were common; the vibration for which these engines are notorious tended to damage the battery and shorten its useful life; the electrical components were not as robust as the "hewn from granite" engines, and did not stand up well to the harsh operating conditions of the construction site applications for which these engines were frequently used. Electric starting was therefore fitted relatively rarely, mainly to the larger engines and especially to engines powering generators, where the lack of robustness of electrical apparatus was a problem that had to be lived with in any case.
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