Earlier than this thread I had helped Bernie ('Cardist') out with
a few drawings & photos of the Cirrus III engine for his very, very nice PWS 50 build.
Since this thread now has been unearthed again, it is appropriate to reproduce some of that material here (in addition to the link given; do check it out, there are a lot of photos of the Cirrus III engine there). Here is the outcome of that work, a sort of photographic four-view of the Cirrus III engine:
This is just an image of the drawing. If you seriously intend to build a Cirrus III engine, please
download a pdf of the Cirrus engine four-view from the downloads section (as soon as it clears the moderation queue).
Leif