Filler Neck Hole

[BTAZ]

That's basically what I did. Built the tank and leak tested it with everything but the fill opening, Installed it in the wing and drilled a small hole through the skin into the tank. Then enlarged the two as required and welded the filler neck to the tank.

[Chewie]

Ah gotcha, so you basically finished building the tank on assembly. It would be a 1:1 match for that particular tank then, right? What I'm pondering is to take a factory finished tank, install and tension it up, and locate the skin to it using the hole before even drilling it to the ribs.

[svyolo]

Left to right, there is no change when you tension it up, only fore and aft. Fore and aft, equalizes when the forces are zero. I think there is a couple of other threads. Mine came out pretty close. I can take a couple of measurements if you want fore and aft.