I got to do a little work yesterday on the Noblarf cowling. I think I have around 9 hours of actual labor and somewhere around 20 hours of thinking about it..!!! So i got the cooling outlets cut, the hole for the igniter driver, the locating pin for the front of the cowl, and the cowl hold down bolt. For the hold down I used a piece of aluminum tubing that was .234 O.D (or so) I believe I used a letter "D" drill. I counterbored the tubing for the 4-40 capscrew, this allows the tubing to clamp up against the fuselage structure.