widow giving me fits

chevyiron420 wrote:Anyway, I installed a retainer off a spare carb and put the steel reed back in and it runs great. Man this thing about drove me nuts. Taking it apart so many times, one by one all the backplate screws busted through and one by one I sleeved them all. I aint taking it apart again but I really want to know what is wrong with that reed. It looks good to me. Phil

Phil, if you look at the design for the reed retainer on later Cox engines, they use a different retaining system. I imagine that the mylar reed being of softer material must have a clipping system that allows free movement along the edges.

With your particular engine, the metallic reed is of thinner composition and the spring clip allows for freedom of movement, but not with the slightly thicker mylar. It may pass the suction test, but that test is static (without much movement). When running the reed is vibrating at the same frequency as the prop is turning. I imagine there is a certain amount of binding under the retainer spring through vibration, which prevents it from snapping back into place.

Perhaps on other engines, the spring clip is of slightly thinner diameter or groove is wider, allowing more movement for non-metallic reeds.

There is certainly nothing wrong with continued use of the steel, copper or brass reed. Any run improvements are subtle and unless you are in out and out competition, should provide good service with that engine.