I re-fit the upper cowling several more times, sanding here and there until I have a uniform paint gap. Then, I cleaned up and shot primer on the upper cowl hinge pieces as well as the backing strip. While the primer was drying, I machine c/s the rivet holes in the cowling. I used some #60 grit on the side of the backing strip that will bond to the cowl. I mixed up a batch of resin with a couple of scoops of flox to thicken it up. I spread this on the cowl for the short piece of hinge. I clecoed the hinge and backing strip in place and squeezed in 17 rivets. Note that the plans call for a -4.5 rivet, but with the backing strip, a -5 rivet is needed. I then used the remaining resin to fill some holes I had drilled in the cowl that won’t be used. Tomorrow I’ll set the other 29 rivets for the upper hinge. I don’t want to rivet the horizontal hinges until I make the new vertical cowl side hinges (remember I screwed them up earlier).