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Looking good! The arms look great! John
Yokes? Clevises? Y-thingies? Whatever they are called, look great!
If its opening 20 degrees late on both directions, then you should be able to shave off a bit on both ends. If its 20 at tdc and something else after bdc, then the timing needs to be adjusted first. It wont take much to change it, but it would help. Also check when the exhaust closes in each direction, too ealy and it will fight the piston, too late and you cant make the steam intake earlier.