i assume a ZX is an all electronic ignition vehicle, in which case there is no real adjustment of it, in the old days it was done by rotating the distributor, modern engines are controled by sensors which are not adjustable. The electronics automaticaly adjust the timing of the engine for optimum running, there is a way of bypassing all this which is what the tuning guys do by remapping the ECU with a laptop and the correct software , a whole new ball game...not really worth the effort on a 94 ZX