SINGLE ENG ACFT DECLARES EMER AND LANDS AT SDM AFTER PWR LOSS.

Narrative

WHILE IN LEVEL CRUISING FLT AT 7000 FT; WE EXPERIENCED A SUDDEN PARTIAL LOSS OF ENG PWR. TACHOMETER WENT FROM 2500 TO 1200 RPM. IMMEDIATELY APPLIED CARB HEAT AND ADJUSTED MIXTURE FOR BEST RPM. RPM CAME UP TO 1500 RPM BUT CONTINUED TO RUN ROUGH. WE WERE LOSING ALT AND ADVISED ZLA THAT WE HAD EXPERIENCED A PARTIAL LOSS OF PWR AND WERE REVERSING COURSE IN VMC CONDITIONS TOWARDS RIEDER AIRSTRIP (PVT AIRSTRIP). CTR STATED; 'ROGER; UNDERSTAND THAT YOU ARE CANCELING IFR; SQUAWK 1200.' I REPLIED; 'NO; I AM DECLARING AN EMER AND AM HEADING TOWARDS RIEDER IN VISUAL CONDITIONS.' CTR THEN HANDED ME BACK TO SOCAL APCH. APCH WAS VERY HELPFUL AND SAID THAT THEY WERE LOOKING UP THE ARPT INFO FOR RIEDER. I TOLD THEM THAT I HAD THE ARPT IN SIGHT; WAS FAMILIAR WITH THE RWY LAYOUT; AND KNEW THE LENGTH OF THE RWY AND THE FIELD ELEVATION (ALL OF THIS WAS AVAILABLE FROM THE SECTIONAL CHART). SOCAL APCH THEN STATED THAT THEY WERE TRYING TO CALL THE OWNER OF THE ARPT FOR NOTIFICATION. AT THIS POINT; THE ACFT WAS ABLE TO MAINTAIN ALT AND I STATED THAT I WOULD LIKE TO TRY TO CONTINUE TO SDM UNLESS I WAS UNABLE TO MAINTAIN ALT IN WHICH CASE I WOULD RETURN TO RIEDER. I ALSO REQUESTED THAT MY RTE TAKE ME TOWARDS NICHOLS FIELD (PVT AIRSTRIP FOR PARACHUTE JUMPING). APCH STATED THAT THEY COULDN'T FIND NICHOLS ON THEIR SECTIONAL CHART (IT ISN'T). I STATED THAT I WAS FAMILIAR WITH ITS LOCATION AND THAT IT WAS MARKED ON MY SAN DIEGO TERMINAL CHART. APCH THEN ASKED ME WHAT TROUBLESHOOTING MEASURES I HAD TAKEN; SOULS ONBOARD; COLOR OF ACFT; AND FUEL REMAINING. WE MAINTAINED ALT UNTIL OVER BROWN FIELD AND STARTED A DSCNT OVER THE ARPT. ENG RPM REMAINED AT A CONSTANT 1200 RPM. ENG QUIT UPON TOUCHDOWN. WE WERE ABLE TO RESTART ENG AFTER SEVERAL ATTEMPTS ON THE RWY AND TAXIED CLR. MECHANICAL INSPECTION BY IA REVEALED STUCK VALVE. SOUTHERN CALIFORNIA APCH CTL: FRIENDLY; RELAXED; OFFERING SUGGESTIONS WITHOUT IMPENDING UPON RESPONSIBILITIES OF PIC. CTLR VERIFYING TROUBLESHOOTING PROCS: NICE TO HAVE A SECOND SET OF EYES IN THAT SIT. FROM A LEGAL POINT OF VIEW; IT'S NICE TO HAVE IT ON TAPE THAT YOU DID EVERYTHING YOU WERE SUPPOSED TO DO TO PREVENT/MINIMIZE AN ACCIDENT.