Abstract: An apparatus and method is provided for testing a spark plug after the spark plug is assembled in an internal combustion engine. The apparatus includes a high voltage test probe to mechanically probe the spark plug. The high voltage test probe includes a non-electrically conductive part, an electrically conductive ring substantially shielded by the non-electrically conductive part, and a high voltage contactor for electrically connecting to a terminal end of the spark plug. The apparatus also includes a high voltage control box having a high voltage source and an electrical ground, and including at least one of an insulator crack detection circuit and a spark plug firing circuit. The method includes using the apparatus to test assembled spark plugs.

Abstract: An apparatus and method is provided for testing a spark plug after the spark plug is assembled in an internal combustion engine. The apparatus includes a high voltage test probe to mechanically probe the spark plug. The high voltage test probe includes a non-electrically conductive part, an electrically conductive ring substantially shielded by the non-electrically conductive part, and a high voltage contactor for electrically connecting to a terminal end of the spark plug. The apparatus also includes a high voltage control box having a high voltage source and an electrical ground, and including at least one of an insulator crack detection circuit and a spark plug firing circuit. The method includes using the apparatus to test assembled spark plugs.

Abstract: A method of testing an internal combustion engine to detect engine defects. After the engine has been assembled, the engine is cranked, gas under pressure is injected into the intake ports, and the pressures developed at the exhaust ports as the engine is cranked are noted and evaluated. The pressurized air injected into the intake ports amplifies the pressure signals developed at the exhaust ports so as to provide more accurate identification of engine defects and detect engine defects that might go undetected utilizing prior art technology.

Abstract: Measurement of curvature and profile of a reflective test surface by simultaneous measurement of slope at two closely spaced points on the test surface. A pair of parallel, nearly collimated light beams, which are slightly displaced relative to each other and of opposite linear polarization, and which intersect the test surface are reflected by the test surface, separated by a polarizing beam splitter and focused onto individual position sensitive detectors, which sense the slopes of the test surface at the points where it is intersected by the beams. The difference between the measured slopes is proportional to the local curvature. The device can be scanned along the surface to give a profile of measured curvature values, which are twice integrated to give the surface profile, although measurement at a single point without any such processing yields the test piece curvature.