By 'moving the point gap slightly to either side' you are rotating the flywheel back and forth a bit to verify that you do, in fact, have the "S" mark centered in the window when the points are just starting to break. The timing is set by having the points open at 20 degrees BTDC, and the timing marks on the flywheel are kept in the proper position because of the flywheel key.
Could you just center the S in the window and close the points and then with a meter just open them until they break without having to turn it over by hand?
|