Decided to try and add a bit more twist to the longerons. I was aiming for about 20 degrees. After clecoing on the skins, this results in just about the 17 degrees required by the firewall brackets. After that, clamping them on was relatively stress free. Something the plans don't say anything about, but the forward 3 inches of the longerons need to be relatively un twisted. They'll certainly end up that way in final construction, after clamping to the firewall brackets. So I did the final twists with the crescent wrench lined up with the aft most 1/8 rivet.
Got the centerline of the bottom firewall stiffener flange lined up in with the aft hole in the 972 and drilled them in. This after getting the rest of the firewall in a reasonably good location. Then spent a bunch of time readjusting the fit to the top longerons, quaduple checking the depth of the firewall face to the leading edge of the 970s.
Got the rivets set into the forward skin/longeron holes. It was difficult to put these in and then tighten the clamps. This would misalign the longeron, making the rivets impossible to pull out with just fingers. I found that tightening the clamps just a little, getting most of the rivets in, then using a punch in the most forward rivet hole to move the longeron into alignment worked well. Then tighten the clamp a little more, check all the rivets for a good fit, adjust with the punch as required, tighten, check adjust, then lock it down. Then the forward rivet slipped right in.
Warmed up dinner, came back out and check everything yet again, and got about 5 holes drilled on the 970/firewall flange, both sides, before calling it quits.
Ordered another 100 silver and copper clecoes from Avery. The buckets are nearly empty, and there's a lot of parts still to attach. I'm fearing I might need yet another 100 3/32 clecoes.
