dyno received my hs50 cam two days ago. i spoke with them and he said they will get to it monday or tuesday. was going to get 18 pound briggs flat head sprigs cut down. i would rather go with briggs 18 lb animal springs with briggs dcsh-102 lower valve spring retainers and dcsh-103 valve keepers. i know the lower retainers need the inner step cut down for the springs to sit correctly. but now im reading the the 103 vale keepers need to be machined to work with the tecumseh valves. what exactly needs to be done. it is not explained in the article. anthony.