I too was an engine bod 1951 to 1956.We were instructed on Bristol Hercules,RR Merlins, RR Derwents and some on RR Avons but worked on Cheeta's, Gypsy's, Pratt & Whitneys DH Ghosts and Hercules . After all this time just the other day got into a discussion on the Hobson RAE Injector and anti -gravity devices as fitted to the Stromberg Carburretor. Google is a good source of info for these, artysand