Abstract: Generally, the invention include a spark plug with a platinum tip partially embedded in one of the spark plug's electrodes. A spark plug according to the present invention may be prepared by first heating the area of the electrode where the platinum tip is to be attached to a temperature such that the platinum tip may be pushed into and embedded in the electrode. Thereafter the platinum tip is welded to the electrode. Heating the electrode allows the platinum tip to penetrate deeper into the electrode material. This deeper penetration or embedment will reduce the operating temperature at the weld interface (junction) which will in turn reduce the thermal stress and hence prevent cracking of the platinum tip. This deeper penetration or embedment will also reduce the rate of oxidation at the platinum tip near the weld junction and hence prevent cracking of the platinum tip.

Abstract: The present invention includes a spark plug with a copper cored ground electrode wherein the copper core has a cross-sectional area of about 1.6 mm.sup.2 to about 3.0 mm.sup.2 and the remainder of the electrode is made from a nickel alloy sheath. The open end copper cored ground electrode is resistance welded to the steel shell using a light welding force of about 100 lbs. coupled with a low welding energy to eliminate voids and embrittlement in the copper core adjacent to the weld interface.

Abstract: Apparatus and method for welding a platinum wire to a ground electrode of a spark plug to form a contact pad of platinum material that is welded to the ground electrode. The ground electrode is attached to and extends from a metallic spark plug shell. The apparatus includes a pivotally mounted nest for receiving and supporting the spark plug shell. A movable welding electrode can be moved into engagement with a lower surface of the ground electrode. The welding electrode has a spherical end surface that engages the ground electrode. The apparatus has opposed gripping fingers that can be moved toward or away from each other. The gripping fingers each have an inclined surface. When the gripping fingers are moved toward each other their inclined surfaces engage the ground electrode to force it into tight engagement with the spherical end surface of the welding electrode. A source of welding current is connected to the wire and to the welding electrode to weld an end portion of the wire to the ground electrode.

Abstract: An apparatus for providing a service reminder when a vehicle has accumulated a predetermined mileage comprises a potentiometer operated by the highest order number wheel of the vehicle odometer to provide an output voltage which changes incrementally with each indexing motion of that number wheel. An electrical detector responsive to the potentiometer output energizes a signal lamp when the output reaches a voltage in a predetermined range representing a desired service interval. An electrical connector in circuit with the potentiometer can be disconnected to change the potentiometer voltage to a value outside the predetermined range to allow the service reminder circuit to turn off the indicator lamp when the indicated service has been performed. The apparatus is adapted to operate in conjunction with an electronic engine control module which can be programmed to detect the predetermined value of the potentiometer output and to operate a signal lamp.