Mike,
The engine crutch assembly is rather fun to build, and is almost impossible
to construct wrong.
Accurately cut out the 1/4"-3/8" balsa filler block that will go between the
hard maple motor mounts. Using slow setting epoxy, securely clamp
these pieces down to a piece of glass, scrap granite, or 3/4" particle board with
a melamine surface. It's preferable to clamp this down with another piece of
flat material on top. After this cures, you can add F1, f2, and F3 insuring that
they are square to the crutch.
In the photo, you can see that I like to drill the holes for mounting the engine
at this time. By having the assembly square to the work surface (in this case
the 3/4" Melamine covered particle board) you can calculate and offset what you
might want on the engine. Clamp your engine in place, adjust for desired
offset (if any) and use the commercial tool pictured for 'spotting' the hole locations
which are later completed on a drill press.
Piece of cake !
Cheers.
Warren Wagner