RE: Sundowner 50 - a few more recent Jett 56 installations
bob one you could have done instead of opening the cooling air hole is to close off the other air holes in the cowl. closing off those other two would have decreased your air inlet to the cowl by 2/3 but gain about 50% more cooling air to the engine. You normally need 2 times the exithole size as inlet hole size. those other two inlet holes in the cowl are only adding drag and letting the engine run hotter.