GalenB,

This might be a dumb question but bear with me. Did you have to insert the extra plywood rib to correct for cowl clearance? There's 1/8 " potential offset to the center of the wing right there. I hope your not trying to center the mounting dowels to the large mounting holes in the fuselage -- thats why they gave you mounting blocks to glue behind those fuselage holes. If you added the extra rib it will look like the illustration attached below:

I finally assembled my wing and had to install 3 extra 1/8" hardwood ribs to provide for clearance of the fuselage and cowl. This puts the middle extra rib right in the center of my wing. When I go to square it up to the fuselage I will measure for the middle of the mounting block. I estimate I barely have enough to clear the large mounting holes in the fuselage -- my mounting block pieces will be nearly to the outside edges of those holes.

Before I can perform the above I have to trim the extra ribs, fill in any gaps with filler, and glass the center of the wing panel.