Has anyone done the above conversion?
Where can I find the documentation for the 337?
Background:
C172N with Penn Yann 180 conversion.  (Lyc 0-360)
Airplains Services 180 conversion includes the battery mod in their STC
but does not have a separate STC.
Penn Yann modifies the battery box in way that is very difficult to deal
with and restricts the magneto timing adjustment.
We are trying to avoid the Field Approval process.
Any info on the subject would be greatly appreciated.
Thanks,
Dave