Confirmed with Vans that the aft side of the F-623 doesn't have to be flush with the skin. The fwd side is the important one. I had already had that discussion on VAF and reasoned out how it had to fit so I had pressed ahead and had them both match drilled by teh time I got the email back from Vans, but it was nice that they backed it up.

Alos remade the front and aft F-623 attach straps. As expected, the aft ones made per print ran into all sorts of edge distance problems so I made new ones that incorporate sort of a bulb on the end to solve that problem. The front ones made per print are to wide and needed to be notched to allow access to buck a river that they don't pick up. I saw at least 1/2 dozen build logs on VAF where other guys have had exactly teh same problem.

The next step was to bolt on the front 1/2 of the F-704. Vans says to space this by making wooded blocks, but the dimension they give you is super critical, because the space determines the width of the wing spar box that the wing spar stubs eventually slide into.

The spar stubs are supposed to be 1 7/16 (1.4375) but when I mic'd mine they were more like 1.439-1.441. I had previously aquired some machined spacers from a guy on VAF that were originally machined by Buller enterprises to exactly 1.438. Buller manufactures these all teh way up to 1.445ish and recommends that you go .003 larger than whatever the actual measurement on your spar stubs are.

I already had these, so I called Van's a while back and discussed with tech support. They told me that I could just go with the 1.438 spacers I had and they would slide home with a little heaving, but that it was no problem if I wanted to go up a little larger as long as I didn't go crazy with it. We agreed that layer of blue painters tape would be consistent and repeatable, so I tried that tonight and it worked great.

Basically, I taped 1 layer of blue tape on one end of each spacer, and when I tightened everything up, the space in the spar box was increased about .002 to 1.440. I think that will be just about perfect for the given dimensions I'm actually measuring on my spar stubs, and I should be able to get the wings to slide home snugly, but without galling or having to resort to prying with axe handles or any of the other solutions i've heard about.