i agree, 12% is not that bad. i think i remember an engineer buddy telling me 9% is still ok for a street engine. i certainly wouldn't tear an engine down for that, not unless you are going after every ounce of power.

i'd leave it, your issues are elsewhere...

slightly different kettle of fish, but i had a 4 cylinder engine with 35% on one cylinder. it ran better than my current one. exact same engine, haven't done a leak down on the current one, but i doubt any of the cylinders are that bad.

get rid of your carb issues, drive it and have fun!