Checking Distributor and Microswitch

CHECKING DISTRIBUTOR CAP
- Check for:
^ dirt, cracks
^ tracking, burnt terminals.

NOTE: Center terminal is not spring loaded.





CHECKING ROTOR
- Two types of rotor are in use. Use only new type for replacement.





CHECKING HALL PICK-UP WIRE
Make sure that the wires cannot be damaged by the rotor.





CHECKING/ADJUSTING BASIC IGNITION SETTING
- Before checking ignition setting check function of microswitch.





CHECKING MICROSWITCH
- With engine off, turn throttle pulley slowly and listen to microswitch.
- A click should be heard when throttle valve moves.





ADJUSTING MICROSWITCH
- Unscrew retaining screws.
- Turn switch clockwise slightly. Then turn switch back until it contacts stop, but no further as throttle valve will start to open.
- Tighten retaining screws.
- Check function.





CHECK THAT BASIC IGNITION SETTING IS 12° +/- 2° AT 12.5 R/S (750 RPM)
- Warm engine.
- Air conditioning disconnected as applicable.
- Increase engine speed to 2,000 rpm for 5 seconds.
- Let the engine idle and check idle quality.
- Make sure the idle is stable and within specifications as variations could affect the timing.
- Check/adjust ignition timing. Adjust ignition setting by turning distributor.





CHECK CENTRIFUGAL ADVANCE
- Disconnect vacuum hose from distributor.
- Run engine at 42 r/s (2,500 rpm) and check that ignition advance is 16 - 24° before T.D.C.
- If incorrect, replace control unit.





CHECK VACUUM ADVANCE
- Run engine at 25 r/s (1,500 rpm).
- Disconnect vacuum hose. Record ignition advance. Reconnect hose and check that advance alters.
- If not, check for vacuum at control unit (check suction at hose).
- If vacuum, but no advance, replace control unit.





CHECK DWELL ANGLE
Read off dwell angle at idle.
Dwell angle should be 36 - 38°.
Increase engine rpm and check that dwell angle increases. if no increase is recorded, replace control unit.





CHECKING KNOCK SENSOR
- Connect a Volvo Monotester or equivalent test meter.
- Start engine (AC disconnected).
- Increase engine speed and maintain at set level by e.g. placing screwdriver across throttle pulley.





- Tap plug on right side on cylinder block with a hammer.
- Ignition should retard by max 6° and return automatically to normal.