I need to know how to set the "gap" between the flywheel and the magneator (17.5hp)

Hi,
It can be done deceptively easily with a business or index card. Turn the magnets away from the armature (the Briggs term for the ignition) and loosen the bolts holding it just a bit (just enough to move.) Place the card between the flywheel and the legs of the armature and carefully rotate the flywheel until the magnets pull both legs toward it. Tighten the bolts snugly and rotate the magnets away to remove the card. Rotate to make sure nothing touches.
Peace,
Clarke