After the Z brackets are bolted on you can plop the gas tank on the wing main spar. All the Z brackets need to to be drilled here. I'm using the tried and true Dan Checkoways methord here. I read the Vans plans and I read Dan's site www.rvproject.com and Dan's approuch assures a perfect alignment between the gas tank, wing leading end section and main wing skins.
First, I used the straps to pull the gas tank down into proper position against the Z brackets and to also close the gap between the tank skins and main skins. It was really haed getting this gap closed. You need to close this gap before you drill the holes on the tank/leading edge joint plate.
Second, back drill through the inboard gas tank rib to drill holes in the Z bracket. The gas tank has some movement left and right at this inboard end. I adjusted it to the center of available motion and drilled. Put clecoes in each hole you drill. I used the long #30 drill bit that came with my Avery tool kit. You can support the bit at the center to bend the bit so that you drill a straight hole. I used a glove to prevent friction burns.
Third, I drilled the gas tank/leading edge joint plate to a #19 hole.
