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Ignorance is not a problem here. In fact, without ignorance there would be no reason for this board to exist.
Adjustable distributors were the norm for many years. The timing of the spark is important to the proper combustion of the fuel. In fact it is not a constant value. The ignition timing varies with engine rpm and load. In the past, this was done with weights and vacuum mechanisms. Today it is more common for the engine control unit to make the neccessary ignition timing changes. The timing in your 87 is controlled and varied by the computer, the 12 degree before top center (BTC) is the base setting for the timing. This means that at idle, the spark occurs 12 (of 360) degrees of rotation before the piston reaches the top most position in the cylinder. As the rpm goes up it is necessary for the spark to gnite the fuel sooner. This is called spark advance. If the spark is too far advanced, the engine will ping or knock. There is a knock sensor on the side of the engine to detect this, and if it occurs, the timing will be adjusted back closer to TDC, or retarded.
Hope this helps.
Dan
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