C185 PLT OVERSHOOTS CRUISE ALT BY 1000 FT DUE TO MISSET ALTIMETER.

Narrative

I DEPARTED WITH AN IFR CLRNC THROUGH A THIN OVCST. MY ALT LIMIT WAS 4500 FT. WHEN MY ALTIMETER READ 4500 FT; I WAS ON TOP IN VFR CONDITIONS. I CANCELLED IFR; AND PROCEEDED VFR WITH FLT FOLLOWING WITH LCL APCH CTLR. AFTER ABOUT 5 MINS; APCH CALLED. THE CTLR INDICATED THAT I HAD CLBED THROUGH 4500 FT TO 5500 FT; BUT NO TFC CONFLICT HAD OCCURRED. I HAD NOT REMEMBERED CLBING PAST 4500 FT WHILE ON AN IFR CLRNC. I ACKNOWLEDGED THE XMISSION AND CONTINUED THE FLT. BEFORE THE VFR FLT TERMINATED; I DISCOVERED MY ERROR. I AM QUITE EMBARRASSED TO ADMIT THAT I MISSET MY ALTIMETER BY 1000 FT PRIOR TO TKOF. I RECEIVED THE LCL AWOS ALTIMETER SETTING OF 30.66; BUT MISTAKENLY SET 29.66 ON THE ALTIMETER. THERE HAD BEEN A 7:8 PRESSURE CHANGE SINCE MY LAST FLT. WITHOUT THINKING; I JUST USED THE LAST 2 DIGITS; IGNORING THE FIRST TWO. FROM THE 'OLD' SETTING; IT TOOK JUST A SMALL CORRECTION TO SET TO THE 'NEAREST' .66 IE; 29.66. THIS WAS MY ERROR. SUBSEQUENTLY; WHEN I 'LEVELED OFF' AT 4500 FT; MY REAL ALT WAS 5500 FT (AS INDICATED BY ATC). I PICKED UP AWOS AND SET THE ALTIMETER WHILE TAXIING. THAT WAS A FACTOR IN MY ERROR. IF I WOULD HAVE DONE THIS PARKED IN THE RUN-UP AREA; I WOULD HAVE BEEN MORE FOCUSED ON DETAIL. ALSO; WHEN I FIRST CONTACTED APCH; I DUTIFULLY INDICATED MY PRESENT ALT. THE ERROR SHOULD HAVE BEEN IDENTED AT THAT TIME. HOWEVER; ATC ACKNOWLEDGED MY RPT AND THE ERROR WAS NOT DISCOVERED. MY ERROR; BUT IN THIS CASE; ATC SHOULD HAVE IDENTED THE ERROR AT INITIAL CONTACT.