In order to determine the rpm limit of the S-7 "I" beam connecting rod, this .80 engine was dyno tested at 38,000 rpm. After about one minute running time the rod failed completly! The carburetor used had a .750 bore; the exhaust timing was 198 deg; the transfer timing was 130 deg & the boosts 125 deg; the inverted drum valve opened 30 deg ABDC & closed 66 deg ATDC; the two stage pipes tuned length was 8.75 in; & the fuel used was 65% nitro.
