As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ABOUT 30 MINUTES INTO A TOUR, PILOT HEARD A SOUND AND EXPERIENCED LOSS OF POWER AND HIGH MANIFOLD PRESSURE. INITIATED POWER ON LANDING ON AN ADJACENT OPEN FIELD. VISUAL INSPECTION REVEALED OIL LEAK NEAR CYLINDER # 6. UPON REMOVAL OF VALVE COVER A BROKEN OFF VALVE STEM TIP WAS IDENTIFIED. NEW STYLE ROTATOR CUP INTAKE VALVE PN 17A29467 INSTALLED.