How do I set the ignition timing on a 1979 FLH Shovelhead?

Before checking timing, check sensor air gap as described previously. To set the sensor air gap: remove spark plugs to permit engine to turn easily and rotate flywheels so that the wide lobe on the trigger rotor (1) is centered in the sensor (2). Check the gap between the rotor and sensor using a narrow feeler gage. If gap is not correct, loosen screws (3) and move sensor as required. Repeat for narrow lobe setting so that gap for both lobes is between 0.004 and 0.006 in. Tighten screws (3) to 5 to 7 in-lbs torque. There are two timing procedures — checking advanced timing with a strobe light and setting retarded timing with a circuit tester. The advanced timing procedure is the primary running check, since advanced timing should be checked and set under running conditions as soon as possible using a strobe timing light. Checking advance timing with a strobe timing light: - Note the interval: ignition timing should be checked initially at 500 miles and thereafter every 2500 miles. - Use a strobe flash light (timing gun) to view advanced timing mark (7) on flywheel through accessory plastic view plug, Part No. HD-96295-65, screwed into timing inspection hole (9). Make sure view plug does not touch flywheel. - Timing light leads should be connected to the front spark plug, ground and battery positive terminal. - Start engine and set engine at 2000 rpm. Light will flash each time spark occurs. - Loosen timer plate screws (5) just enough so that plate (4) can be shifted using a screwdriver in notch (6) as light aimed into inspection hole (9) stops timing mark (7) in center of hole. Note that timing will retard 32° automatically when engine is at idle speed or is stopped. - For the rear cylinder: rear cylinder advance timing mark is a single large drilled dot which should appear on or near the front cylinder advance timing mark while viewing with timing light. Setting retarded timing with a circuit tester (for use when a strobe light is not available or after reassembly): whenever ignition components have been disassembled such as during engine disassembly and reassembly, or if a strobe timing light is not available, approximate timing can be obtained by using the following procedure. Be aware that this procedure will result in approximate timing and engine can be operated in an emergency for a short period of time. - Remove screw plug from timing inspection hole (9) in left side of crankcase. Then remove front push rod cover so that opening and closing of valve can be observed. - Turn engine in direction in which it runs until front piston is on compression stroke (just after front intake valve closes), and continue turning very slowly (less than 1/2 revolution) until piston top dead center timing mark (8) on flywheel is aligned in the inspection hole as shown. - With timer rotor fully retarded, the leading edge of the narrow rotor lobe should be aligned with the center of the sensor body as shown in Figure 8-2. At this point the retarded front cylinder ignition spark occurs. - A circuit tester, such as a 12-volt light bulb (No. 57) can be used to determine the exact point of ignition firing: Disconnect the blue wire from the ignition coil primary terminal and connect test light to this terminal and to end of removed blue wire. - Loosen timer plate screws (5) just enough to shift timer plate (4) using a screwdriver in notch (6), so light goes on or off when piston top dead center timing mark is aligned in inspection hole (9) as shown in Figure 8-3. - Tighten screws (5) to 12 to 16 in-lbs torque. For reference, the flywheel marks are identified as (7) advance (35°) timing mark, (8) fully retarded (3° B.T.C.) piston top center mark on flywheel, (9) timing inspection hole. A final caution when reassembling: when reinstalling the control module and timer compartment cover, make sure that wires are not pinched between the control module and internal components.