Classic/Antique Car Repair: piston travel and crank degrees-, time jack, piston

Question
Has anyone done the math to know how many thou. the piston is down from TDC when the crank is 10 degrees BTDC. Also how many degrees change should the spark advance provide? Regards Doug.--31 Model A--

Answer
I don't know of anyone who has made a study like that, but I'm sure some one has.  The A does not care too much about timing.  On the road, we time it by sight, where it was when we took it apart.  When we have the time, I use the light connected to the the movable point arm and ground.  If you follow the book, (Les Andrews, Model A mechanic handbook) using the light, it comes out perfect every time.  
jack