Checking Distributor

CHECKING DISTRIBUTOR CAP
- Check for:
^ Dirt
^ Cracks
^ Burnt terminals, tracking
^ Worn rotor.
^ carbon brush for wear or damage

IMPORTANT: To prevent retaining springs from damaging rotor do not crank engine when distributor cap is off.





CHECKING ROTOR
- Replace rotor if cracked or excessively burnt.
- Resistance: 5 +/- 1 K ohms.





CHECKING IMPULSE SENDER
- Measure resistance of sender.
- Resistance: 0.95 - 1.25K ohms.
- Check that no arcing to earth occurs.
- If meter pointer swings to far right (i.e. open circuit) remove impulse sender and check if sender or lead is defective.





CHECKING AIR GAP
- Set rotor and stator tips opposite each other and measure air gap with feeler gauge.
- Air Gap: min 0.25 mm (0.010 in).
- Adjust if necessary.





CHECKING/ADJUSTING BASIC SETTING AT 11.7 - 13.3 R/S (700 - 800 RPM)
- Disconnect hose from vacuum control unit.
- Adjust ignition setting to specification.





CHECKING CENTRIFUGAL ADVANCE AT 42 R/S (2,500 RPM)
- Check that ignition advance is according to specification.
- If not, examine centrifugal advance mechanism.

IGNITION SETTING
- Ignition setting is before T.D.C. with vacuum disconnected vacuum control unit.
- With effect from 1976, vehicles for the USA and Canada have details of ignition setting stamped on a plate to left of engine compartment.





CHECKING VACUUM ADVANCE
- Connect a vacuum pump to vacuum unit.
- Run engine at idle speed and record ignition advance.
- Pump vacuum pump and check that ignition setting advances.
- If ignition setting does not advance check vacuum control unit.





CHECK BOSCH NUMBER ON DISTRIBUTOR AND USE APPROPRIATE ADVANCE GRAPH IN SPECIFICATIONS.
- Select pressure from graph and pump up vacuum pump to this value.
- Record ignition setting.
- Subtract basic ignition setting and check that value conforms to graph.





EXAMPLE: BOSCH DISTRIBUTOR # 0 237 002 038
- You select a pressure of 200 mm Hg.
- Crankshaft degrees at this pressure is 9 - 14°.
- Basic ignition setting is 10° which means that 19 - 24° should be recorded at timing test.





CHECK VACUUM CONTROL UNIT FOR LEAKAGE
- Connect a vacuum pump.
- Increase vacuum to 67 kPa (500 mm Hg).
- Pressure should not drop by more than 13.5 kPm (100 mm Hg) during one minute.





CHECKING IGNITION RETARD
- Applies to Turbo Engines only.
- Connect pressure gauge 5230 and pump 5496 to vacuum control unit.
- Start engine and run at idle.
- Record ignition advance.
- Increase pressure to 30 kPa and read off ignition setting.
- Ignition setting should drop 3 - 7°.
- Disconnect pump and pressure gauge. Reconnect hose.