Cowl Pucker

[Bill Dicus]

My RV-8 has only 10 hours flight time but no significant pucker noted up to VNE. Hinge is not continuous. Pins are bent in a triangle at the end per Jim Phillips and won't come out. The entire aft edge of upper cowl lifts about 1/8 or less I think.

[sf3543]

As others have noted, this is pretty normal. There are a couple of things you could try...
Check the diameter of the hinge pins being used. If they are too small in diameter and causing a lot of slop the puckering will be worse. They could be worn, too. Using a little larger diameter would help.
On a couple of planes, I have strengthened the area by laying a couple layers of glass in that area, extending several inches beyounpd the gap area on each side, on the under side of the cowl. It seemed to help.
If you go the fiberglass route, you could create a tab the extends beyond the fuselage edge, kind of like a hinge replacement tab, in the gap. The cowl would not pucker if you did that, but make sure you allow for inserting the hinge pins.
You could rivet a metal tab on to the fuselage to fill the gap, that extends under the cowling a bit. (Or use a piece of baffle material. You could even try glueing the baffle material under the fuselage lip. The positive pressure would push it up against the cowl, but being more flexible, it may not work as well.)
You could add a metal tab on to the fuselage, extending under the canopy, with a nut plate so that you could secure the cowl to the tab with one or two screws. This would have the added benefit of keeping the hinge pins locked in.
Ok, those are all my ideas. Hope you get it resolved.