Murray Jamieson Twin Cam Motor
This short stroke 744 c.c. engine had wet liners and valve gear suitable for development to 12,000 r.p.m.. The initial calculated output was 134 b.h.p. at 9,800 r.p.m. but it never developed more than 116 b.h.p. at 9,000 r.p.m. The camshafts were gear driven from the back of the engine, these gears also drove the Roots blower at 1.5 times engine speed and 22 Ibs pressure. The compression ratio was 6.5 to 1 and the magneto was a Swiss Scintilla. There was a triple-stage oil pump with pressures of 10 lb./sq.in. and 100 lb./sq.in. On its first run on the bench it developed only 22 b.h.p. without a blower, but when the blower was added, the output reached 90 b.h.p. at 8,000 r.p.m
These comments are taken from "Austin from the Inside" by Freddie Henry. This book is available from the 750 Motor Club.
The Austin Seven Motoring Pages