1. Check base ignition timing with engine at normal operating temperature (cooling fan comes on). Connect timing light. With engine at idle, Red mark on crankshaft pulley should align with pointer. See Fig. 1. If not aligned, adjust timing. See IGNITION TIMING table in this article.
2. Ignition timing is adjusted by turning adjusting screw on ignition timing adjuster. See Fig. 2. Remove control box upper and lower covers. Using a 3/16" drill bit, drill out 2 rivets from adjuster and remove cover.
3. Turn adjusting screw counterclockwise to retard timing, and clockwise to advance timing. After adjustment, install cover to ignition timing adjuster with new rivets. Install adjuster in control box.