How many tenths of millimeter does the opening, the admission advance or lead steam , of that locomotive have? Excuse my bad English. Regards from Argentina!
They only give the rough setting because it varies for every locomotive. Variables such as lap, lead, total valve travel, eccentric crank throw/pitch circle, and reversing link dimensions are different for every locomotive. Once the set of variables for your particular locomotive is known, then you can set about scribing the lines for the dead centers, and adjusting the valve gear to give the proper valve events. Really "Accurate Setting" comes down to minor adjustments and feeling out the engine until you know you've got it dead nuts (given that the valve gear components are machined properly to the correct tolerances and set up right). What they've explained and demonstrated here is a good enough guide to go by for the beginner. It takes skill and finesse that you only gain through experience and doing it for yourself.
If you want to reverse the block in the link reverse the eccentric crank have you seen a Garrett both ends going in same direction both eccentrics ether up or down one end has its cranks Reversed lovely model coal fired char we are having trouble getting char in Australia some people are gas firing Ron
