ORIGINAL: Gray Beard
It depends on the plane itself. You match the spinner to the cowl or you just put on what looks the best to you. I just used a big odd shaped spinner because it was the heaviest spinner I had, it helped locate the CG. I also miss measured the plug when I was making a glass cowl so when I cut back the cowl it fit better then any other I had on hand.
+1 I go with what matches the cowl. I really don't like the small spinners on the larger cowls. Of course, in some cases I use what I got
