Pissed off with motor, want to change

Not to my knowledge. a lean carb can cause spitting back through the carb, though.

However, at TDC, when timing is set to 0, the rotor should be 5-15 degrees AFTER the #1 wire location on the distributor. Therefor, as the mechanical advance kicks in, the it gets closer to center and then a few degrees positioned BEFORE the #1 wire location.

Obviously, the cap and distributor body are stationary during the entire event, but the shaft that the rotor/reluctor is attached to is "spring loaded" with the advance weights, and actually changes relative position to fire the cylinder earlier. This is obvious when you remove the cap, and you can rotate the rotor button shaft 30 degrees or so, while the engine is off.

If you are using a "stock" distributor, it may be putting as much as 30 degrees mechanical in, as well as another 10 degrees vacuum, for 40 degrees total. If you set the timing at 15 degrees like you mentioned, then you could literally be firing at 55 degrees BTDC!

Since the Distributor rotates once for every 2 engine rotations, that means the spark has to jump 1/2 that range of advance, e.g. 27.5 degrees.

360 degrees/8 = 45degrees. If the starting position of the rotor is aligned too close to the #1 position on the cap. Thus, when you add 27 degrees, you are over 1/2 way to the next cylinder in rotation, and all kinds of weird things happen.

FWIW, unless you have limited the amount of mechanical in the distributor, I would not go past 10 degrees BTDC.