The Van's instructions are a little weird in this section in that it shows you in a figure on an early page to trim back to a scribe line, which, if you do (I did) will probably make the spinner sit flush with the rear spinner bulkhead. Then on a following page, it tells you to trace the aft edge of the spinner bulkhead on the inside of the spinner. Well, no because that fiberglass is already gone when you trim to the scribe line. No matter. In truth, some of the spinner is about 1/64" from the aft edge of the bullhead, but I filed the bulkhead down to get rid of tooling marks . It's fine. Anyway, I drilled the pilot holes, fit the spinner, and drilled to the backplate. Then I made up the spinner cutout cover plates. Then I removed the props and the forward hub and spacers and drilled the cutout cover plates to the bulkhead spinner.