Setting:
Spraybar: Cox Medallion .049
Needle: Cox Medallion .049
Propeller: APC 5 x 3
Control Ring: Own manufacturing.
Fuel: Castor20%/Nitro20%/Rest Methanol
RPM range: 8200/13500
Glow Plug: O.S. 8
Conclusion:
This is the best performance I have obtained for this engine using the self-made acceleration ring.
Thanks to everyone who contributed information (Friends of Cox Engine Forum and Horacio Banus).