Bit of an update to my small project.
Using a transfer punch, I marked the mounting holes. I didn't take any pics in the drill, then tapped the threads, 3x 3/8" UNC & 6X 5/16" UNC.
Now I need to visit my good mate & use his broach to cut the 3/16" key way.
This the std balancer (2.5lbs)& the Super Damper(8.5lbs) for comparison.
I then machined a .060" shim from brass, I'm not sure what this does, but was told some years ago when fitting a larger balancer to these cranks to use a .050"-.060" brass shim, as the cranks have a habit of breaking with the extra weight & this helped to stop it. Maybe some one may have an opinion on this subject.