Hello Dave
When installing a new cam gear onto a new cam It is Best to OIL Heat the Gear. (alum Gear)Then press it onto the cam. Because if the gear is not heat You can ALMOST Count on the fact IT will come off. Because the alum Will sheer Out from the center as the gear is being Pressed onto the Cam. Now as to the umbrellas No they are not need Esp. if you just had the head rebuilt. and new guides installed. Or at least Renurld. Hope this helps }[oooooo]