As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENGINE MISSING & VIBRATION ON TAKEOFF. PILOT STATED THAT THE VIBRATION WAS SEVERE AND THOUGHT THE ENGINE WAS GOING TO QUIT. LANDED. ON INSPECTION, NR 4 CYLINDER COMPRESSION WAS MEASURED AT 78/80. PERFORMED SB 388C. VALVE TO GUIDE CLEARANCE WAS MEASURED AT .031" WHICH IS OUT OF ACCEPTABLE TOLERANCE (.030" MAXIMUM).