I HAVE SOME RESULTS ON MY ECHO WACKER CONVERSION. I STARTED MY TEST RUNS WITH ONLY THE FLYWHEEL FINS REMOVED AND REBALANCED. ALL ELSE AS IT WAS IN THE WACKER. ORIGINAL CARB WAS A WALBRO WT852 #20 VENTURI .312/8MM 50:1 GAS WEAS USED IN ALL TESTS AND A 16-6 K SERIES MASTER PROP. THIS IS A USED ENGINE THAT WAS GIVEN TO ME CAUSE HE COULDNT GET TO RUN (GUMMED CARB) EASY FIX. STOCK CONFIG = 6900RPM RAN VERY SMOOTH MINIMUM VIBRATION IDLED PERPECT TO 1500RPM.
CHANGED CARB TO WA125 #24S VENTURI .367/9MM = 7140RPM IDLE DOWN TO 1900RPM NOT AS SMOOTH HAD MORE VIBRATION AT LOW SPEED. THEN I REMOVED THE OUTER COVER AND SPARK SCREEN FROM THE MUFFLER =7380RPM SAME IDLE RPM KINDA NOISEY.
NEXT I RAISED THE EXHAUST PORT .100 TO MOVE THE TIMING FROM 115 ATDC TO 101 ATDC (A LITTLE CONSEVITIVE FROM KEITH'S 98 ATDC) OPEN MUFFLER = 7800RPM I PUT BACK ONLY THE COVER ON THE MUFFLER AND DROPPED TO 7600RPM
SEEMS LIKE I STIL NEED EXAUST WORK BUT IM NOT SURE WHERE TO GO NOW. I GUESS THE COMPRESSION SHOULD BE NEXT BUT IM NOT SURE BOUT HOW MUCH TO TAKE OFF THE CYC BOTTOM "AS FAR AS YOU CAN" IS TO OPEN FOR ME. ILL HAVE TO REDO THE EXHAUST PORT AFTER I DROP THE CYC DOWN. PORTING ON THE INTAKE SIDE IS GOOD BUT THE TRANSFERS ARE ALITTLE LOW 48 BBDC COULD GO TO 58 BBDC. HTIS CYC AND PISTON MACHINING HAS ME WORRIED. THIS ENGINE IS TO HEAVY FOR IT TO ONLY TURN A 16-6 TO 7800RPM'S 3.75 LBS READY TO INSTALL COMPLETE PROP SPINNER MUFFLER CARB READY TO RUN!