What was found
ENG RUNS ROUGH. ENG MISFIRES. HISTORY: 2/25/2004; TACH 487.1 - REPLACED LT AND RT MAGNETOS. ACFT RUN UP CHECKED OUT OK. 4/26/2004 TACH 508 - CHECKED TIMING. 05/11/2005 (NO TACH) - TROUBLESHOOTING ROUGH ENGINE. REMOVED INTAKE MANIFOLD AND FLAT SAND FLANGES AND REMOVE DENTS. REPLACE ALL INTAKE FLANGE GASKETS AND HOSES. PRESSURE TEST INTAKE MANIFOLD. REMOVE AND REPAIR MA4-5 CARB. RUNUP OK. 8/16/2007 TACH 542.7 - CHECK MAG TO ENG TIMING. RUN-UP AND LEAK CHECK OK. SOLUTION; TACH 573.8 USED DAIL INDICATOR AND FOUND THAT UTILIZING TIMING MARKS RESULTS IN 20+ DEGREE RETARDED IGNITION. USED DIAL INDICATOR TO SET PROPER TIMING AND ENGINES PERFORMS AS IT SHOULD. (K)