Abstract: Methods and apparatus for determining and assessing the accuracy of exhaust gas measurements using the total emission method is provided which allows for virtually real-time determination of the presence of a source of inaccuracy in the total emission measurement, thereby notifying an operator to interrupt the test prior to its completion to search out the source of the inaccuracy. In accordance with one aspect of the present invention, the measured total hydrocarbons are treated as unburned fuel (C.sub.8 basis) plus burning zone hydrocarbons (C.sub.1 basis).

Abstract: Disclosed herein is a four-stroke internal combustion engine including a cylinder, a device for feeding fuel to the cylinder, a sealed crankcase chamber associated with the cylinder, a piston reciprocally movable in the cylinder and relative to the crankcase chamber to effect alternation of the pressure therein in response to piston reciprocation, an oil sump adapted to contain lubricating oil, a conduit system for recirculating oil from the sump to the crankcase chamber and from the crankcase chamber to the sump in response to alternation of the pressure in said crankcase chamber, an oil pump communicable with the oil sump and with the fuel feeding means, and a conduit operably connected to the oil pump and to the crankcase chamber so as to effect delivery of oil from the sump to the fuel feeding device in response to alternation of the pressure in the crankcase chamber.

Abstract: Disclosed herein is a four stroke internal combustion engine comprising a cylinder head fabricated of metal and including an intake manifold mounting surface, and an intake passage including a port in the intake manifold mounting surface, an intake manifold fabricated of metal and including a cylinder head mounting surface, and an intake passage including a port in the cylinder head mounting surface, a fastener connecting the intake manifold to the cylinder head with the ports in registration and with the cylinder head mounting surface and the intake manifold mounting surface in metallic surface-to-surface contact, and a seal between the intake manifold mounting surface and the cylinder head mounting surface.