An engine ignition control apparatus for controlling ignition of a multi-cylinder, 4-cycle engine includes dual ignition coils for controlling ignition timing of the respective cylinders during engine operation. The seat and the seat-supporting structure are provided with arrest means defining a plurality of clamping positions for clamping the seat. The time-voltage conversion circuit allows the capacitor to generate a charging voltage corresponding to the phase of the pulsating flow. Furthermore, the presence of a resistor in parallel to the capacitor allows the energy to be rapidly dissipated when a failure occurs. The narrow upstream end of the conical inner structure has a catheter port with a resilient seal that is sized for passage of a catheter shaft.