If, by coil, you are referring to the ignition armature and since you didn't specify what brand of engine you have I will give you instructions for Briggs: ((The instructions are similar with MOST engines with a few variances.))
Disconnect the spark plug wire from the spark plug, remove the blower housing from the top of the engine (That is the half round/half square metal cover on top of your engine, this will give you access to the ignition armature: Installing And Adjusting A New Ignition Armature
An ignition armature
must be set at a precise distance from the flywheel. Ask your Briggs & Stratton Authorized Dealer
or consult our Engine Check Chart
for the proper gap for your engine. Common armature gap ranges are .006- .010" and .010 - .014". Armatures are often packaged with a shim toassist in setting the gap. Microfiche or index cards of the properthickness also work well.
- Remove the old ignition armature mounting screws (image A). Then, disconnect the stop switch wire from the flywheel brake and remove the armature.
- Attach a replacement armature from the original engine manufacturer, using mounting screws (image A). Then, push the armature away from the flywheel and tighten one screw (image B).
- Turn the flywheel so the magnets are on the opposite side from the ignition armature (image C).
- Place the appropriate shim between the rim of the flywheel and theignition armature. While holding the shim, turn the flywheel until themagnets are directly adjacent to the armature (image D).
- Loosen the tight screw so the magnets pull the ignition armatureagainst the flywheel and shim. Then, tighten both mounting screws androtate the flywheel until the shim slips free.