Hello from Williams..FWIW..The function of a key on a TAPERED shaft is to locate the flywheel during assembly..The key is soft and will shear if the flywheel nut gets loose, it will not keep the flywheel from turning ...I have been converting chainsaw engines for 16 years, quit using keys about 15 years ago...Our 32 HP converted 289cc racing drone engines have no key, never had one..the hub has not shifted in 2 1/2 years of racing..You can throw away the key and just use loctite on the taper and lots of force on the nut or hub, no problem..The amount of gain by using an offset key is not worth the cost of the key, unless the engine was originally timed very retarded...Most engines run best around 28 degrees BTDC.....