Recently got my BC12d, and it has an a65 in it. it idles just fine at around 700-800 rpm, and it runs fine at cruise. However in the transition at around 1300-1500 rpm the engine runs extremely rough and lags. It doesn't matter if you push in the power slow or quick, the engine always stutters before...

FOR SALE - Set of four cylinders for A65 Continental Engine. Reworked by Brown Aviation in Tulsa. Many new parts, Valves, Seats, Guides, etc. Chromed to standard size. $4000