A KOLB-FULLER MKIII HOMEBUILT EXPERIMENTAL ACFT ON INITIAL CLB AT 1200 FT DECLARED AN EMER AND RETURNED TO THE FIELD DUE TO ENG FAILURE.

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AFTER TKOF; R-HAND N DEP WAS IN PROGRESS. THE ENG STARTED RUNNING VERY ROUGH. CMA TWR WAS CONTACTED AND I WAS GIVEN INFO FOR R-HAND TFC AND CLRNC TO LAND. UPON TURNING BASE; THE ENG STOPPED AND WOULD NOT RESTART. A SAFE RWY 26 LNDG WAS MADE ALONG WITH GND ROLL TO TXWY A. THE ACFT WAS HAND PUSHED TO CLR THE HOLD SHORT LINE. NO TFC DELAYS OCCURRED AS A RESULT OF THIS INCIDENT AND NO ACFT DAMAGE. I HOLD AN AIRMAN'S REPAIR CERTIFICATE FOR THIS ACFT. THE ENG IS A REVMASTER MODEL 2100 D. AN OIL CHANGE AND VALVE ADJUSTMENT WAS ACCOMPLISHED 6 HRS PRIOR TO THE INCIDENT. UPON REMOVAL OF THE VALVE COVERS; INSPECTION REVEALED THAT 1 PUSH ROD WAS NOT UNDER THE #3 EXHAUST VALVE ROCKER AND THAT BOTH EXHAUST VALVE ROCKERS WERE FROZEN TO THE ROCKER SHAFT. THE VALVE ROCKERS; SHAFTS; AND PUSH RODS WERE TAKEN TO THE MANUFACTURER FOR EXAMINATION. A ROCKWELL HARDNESS TEST WAS ACCOMPLISHED ON THE PARTS AND FOUND TO MEET THE MANUFACTURER'S SPECS. THEIR EXAMINATION INDICATED THAT THE PROB APPEARED TO BE OIL STARVATION. NEW REPLACEMENT SHAFTS AND EXHAUST VALVE ROCKERS WERE PROVIDED. THE NEW PARTS WERE INSTALLED AND THE ENG HAS BEEN GND RUN FOR 20 MINS. THE OIL USED DURING THE ENG FAILURE WAS KENDALL 20-50. REVMASTER SUGGESTED THE OIL BE CHANGED TO PENZOIL 20-50 WT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE ACFT WAS BUILT BY THE RPTR AND HAS A MODIFIED VOLKSWAGEN ENG. THE RPTR SAID THE ENG FAILURE HAD 1 OF 2 CAUSES: TYPE AND BRAND OF OIL USED OR IMPROPER VALVE ADJUSTMENT PROC. THE RPTR SAID HE RECENTLY HAD ADJUSTED THE VALVES AND MAY HAVE ALLOWED TOO GREAT A CLRNC. THE RPTR STATED THE MANUFACTURER GAVE THE RPTR NEW ROCKER ARMS AND RECOMMENDED A DIFFERENT BRAND OF OIL.