Hi
When converting a plane from standard (single) prop nose ring configuration to a Contra nose ring setup, the general advice is to align the Contra for zero deg right thrust and maintain the existing downthrust angle

Is there a jig or easy way to set the motor to zero thrust when installing the Contra/mount?

Ive seen conversions where the nose ring is cutoff to achieve zero degrees and others where a shim is built and attached to achieve zero degrees

Any advice would be appreciated (planning a new build in an airframe designed for single prop but would like to try new Contra)

thanks

My advice would be that if you don't have the building skills to do the necessary surgery to the nose of your pattern plane to accommodate a CD, find an experienced builder in your area that has successfully performed the modification. I've done a total of 3 modifications in the last 8 years and found each one to be different and not very easy to do in order to "get it right".