George,


Not only the spinner back-plate needs to be drilled for the prop-hub's bolt-pattern, but also the prop itself.

The prop must be drilled so it is mounted at a convenient angle for the starting fling.


With the new ignition system provided by MVVS for their gas engines, this is a bit less critical, but you would still be more comfortable if the prop blade is at about 1 o'clock before it is flinged to start.

If the spinner's back-plate isn't keyed to its cone, this is not a problem...