under the flywheel
It requires a special puller.
No. It positions the flywheel in the proper place for the ignition timing.
Most of the Briggs engines can be gapped simply with a business card between the flywheel and the magneto.
The coil is under the cowling on top of the motor where the flywheel is.
use a wheel puller
If you know your part number of even model number, you can go to eReplacementParts.com for the Briggs and Stratton parts your looking for. The site features part lists for each engine or motor and includes thousands of detailed diagrams to help you replace the flywheel once you get it. All in all, they are a very good site for finding tool parts in general but for Briggs and Stratton parts, eReplacementParts is the place to go.
It is the whole assembly containing the pull start (if applicable) or the metal or plastic shroud surrounding the flywheel (it spins when you start the engine ).
There is no way to adjust the timing on a 17.5 Briggs engine. The magnet is on the side of the flywheel and there is only one way the flywheel can line up. All you can do is make wure that the coil is gapped correctly.
Turn the flywheel to BDC (bottom dead center) as you continue to turn the flywheel into the combustion stroke, it will be the first valve to move.
Most people use a standard business card between the magnetto and flywheel.
Your flywheel key might be sheared