THE PRIMARY VACUUM SYS OF A VFR BELLANCA SUPER VIKING FAILED IN IMC. THE ALTERNATE VACUUM FUNCTIONED AND THE PLT FILED IFR RECEIVING A LOWER CLRNC TO VMC.

Narrative

SHORTLY AFTER TKOF FROM ZZZ; I REALIZED I WAS GETTING INTO CLOUDS AT ONLY 1350 FT (OR SO I THOUGHT FROM GLANCING AT THE ALTIMETER); SO I BEGAN THE PROCESS OF AIR FILING AN IFR FLT PLAN. WHEN I WAS CLRED TO CLB IMC TO 4000 FT; I NOTICED THE ALTIMETER WAS NOT MOVING AND THE OFF FLAG WAS DISPLAYED IN THE ATTITUDE INDICATOR. I RPTED THIS TO ATC AND LATER; WHEN PROMPTED; DECLARED AN EMER. I USED THE TURN COORDINATOR TO MAINTAIN WINGS LEVEL; THEN SWITCHED TO THE ALTERNATE STATIC SOURCE. THE ALTIMETER THEN BEGAN TO WORK; AND I SWITCHED ON THE AUTOPLT TO BETTER IMPROVE MY SIT. THE ATC SUPVR THEN CAME ON FREQ TO ADVISE ME THAT I SHOULD BE ABLE TO GET CLR OF CLOUDS IF I DSNDED. I DID THAT AND BROKE OUT OF THE CLOUDS AT AROUND 3000 FT MSL. I CONTINUED TO ABOUT 2800 FT THEN HEADED DIRECT TO HOME BASE. IN RETROSPECT; THE FAILED ALTIMETER WENT; INITIALLY; UNNOTICED CAUSING ME TO FEEL THE NEED TO FILE IFR. LASTLY; I WAS PICKING THE PLANE UP FROM EXTENSIVE 'BEHIND THE PANEL' WORK AT THE AVIONICS SHOP. LESSON LEARNED!