Offset Flywheel Ignition Timing Keys for GX390 and Clones

Offset flywheel key to accurately advance ignition timing. 

Ignition timing advance is critical to horsepower production. Stock industrial engines have very little ignition timing advance because they are made to only rev to 3600rpm, but if you are removing your governor and running longer duration cams to help make power at higher engine speeds you will need to increase your ignition advance so that the spark fires early enough for the flame front to encounter the piston when it can effectively put force into it. Fire the plug too late and your piston will already be running away from top dead center before the flame front can impart combustion forces to it, and that kills horsepower. 

When burning gasoline you'll want anywhere from 24 degrees of ignition advance all the way up to over 30 degrees for high revving methanol burning race engines. Check your cam card for advice on what ignition timing works best for the RPM range that your engine will be running with that cam.