The cowling halves pulled apart just fine. The keys are very solid; however, some filing and sanding was in order to clean up the edges. Next, measured and cut the rubber flange for the rings. Riveted them in place to the plenums, then adjusted the rings so that they will be in their proper spot for taking off then putting on the cowling halves. The band clamp will be semi-permanent on the back side of the rings. The results are much better than I expected.
