A '41 COE, cool! The lifters are solids and will usually be a little noisy. I would do the oil change first. To adjust the valves the engine needs to be warmed up completely. I don't have a book for a '41 but the '51 216 book says to set the intakes at .006-.008" (hot) and the exhausts at .013-.015" (hot). My grandpa used to set them as the engine was running but I believe there is a way to set them with the engine off. Maybe someone else can help with that procedure. Good luck.