On March 3, 1995, approximately 2030 hours Pacific standard time, a Cessna 150H, N6663S, registered to and being flown by a certificated private pilot, was destroyed during collision with terrain following a total loss of power while en route to Lebanon, Oregon. The aircraft crashed approximately three miles north of Albany, Oregon, and the pilot sustained minor injuries. Variable meteorological conditions existed and an IFR flight plan had been executed. The flight, which was personal, was to have been operated under 14CFR91, and originated from Pendleton, Oregon, with a fuel stop at Mulino, Oregon. The pilot reported that he had inadvertently entered a cloud while descending at about 3000 feet msl. He initiated a climb and obtained an IFR clearance to Corvallis, Oregon. He was then cleared to descend to 4000 feet and broke out of IMC over Albany, Oregon. He then canceled IFR, reduced power from 2600 to about 2200 rpm, and quickly descended to 2000 feet for the remainder of his flight. He stated that shortly after reaching 2000 feet the engine quit and the prop stopped without warning. The pilot executed a forced landing under dark night conditions during which the aircraft impacted a power pole and came to rest inverted in a residential yard. The pilot also reported in an interview with the investigator in charge that he acquired five gallons of (unleaded) auto fuel while at Mulino as the aviation fuel supplier was closed. This fuel was transported in a metal container and poured into the left wing tank and mixed with the remaining aviation fuel. The pilot also reported that he utilized carburetor heat on the Pendleton-Mulino leg of his flight but did not use it after departing Mulino. Inspection of the aircraft by the FAA revealed that the carburetor heat was in the cold position, and no mechanical discrepancies were found. The pilot stated that he believed the engine stoppage to have been due to carburetor icing which was not preceded by engine roughness or power decrease. The aircraft had been modified by installation of a Lycoming powerplant using a supplemental type certificate.