I've got a Sears 4.5 Model #21759162, Serial # 204089. I think it is an "Eska/Tecumseh" from the early 70s and I know they changed the ratio right about then. Would this be a 50:1 or a 24:1? Also, any recommendation on which plug to use and what gap? It runs good...I don't want to hurt it with...
