Posted for <dskeele@bellsouth.net>:

 Matt,
    I got my spring loaded alt air door from a salvage yard off a PA -28
Pipers' Air Box ( same engine O-320), cut the base down in diameter and
mounted it on the bottom of the Box with AN-3 bolts clear thru the box.  which
coincidentily holds the K&N Filter from collapsing.  No engineering on my
part, engineering by Piper.  Rigged a small wheel and lever arm to open it
manually with a Belsen Cable from the Panel, for peace of mind.  A while back,
ago I encountered  iceing conditions after a heavy rain and was glad I had the
manual alt door opener.. Hope this helps.. Don Skeele  A&P 235/320