Club Night Forum Failures and How to Avoid Them


Notes from a technical forum evening of the DA7C hosted by Phil Whitter

Rotor Arm
*  Carry tried and tested spare
*  Try to use new old stock whether Lucas or Bosch 009
*  Check Lucas for correct rotation as arrow
*  Solder wire across Bosch to short out ballast resistor which goes disconnected on Chinese imports
*  Check carbon brush
*  If not rotating drive gear may be stripped !
*  If disconnected gives weak spark and pitted points
*  Use old stock as more reliable than Chinese items
*  Check for screw loose on clamp
*  Bob weights can be seized causing engine not to rev as adv/retard not working
*  Need to lubricate adv/retard bob weights
*  Need to restrict advance on Bosch with blue crimp sleeve as it is designed for VW engine
*  Lubricate shaft on Bosch as not splash fed like VW engine
*  Ensure anti lift screw fitted and tight
*  Check cap not cracked
Contact Breaker
*  Ignition battery feed wire loose or disconnected
*  Loose screw or rivet on base plate
*  Loose screw on condenser
*  Spring can touch body of distributor
*  Smear cam with Vaseline or grease
*  Very sparingly lubricate pivot
*  Fit Accuspark but not optical system like Lumenition
Coil Weak Spark
*  Fit new coil from quality source
*  Use Lucas or Bosch from Germany or Brazil
*  Ensure reads 6V or 12V at the coil with engine off
*  Check polarity correct
Plugs Oiling/Sooting
*  Rebore
*  Carb jets
*  Wrong plugs
*  Use Colourtune for mixture
*  Champion D16 good with 20 thou gap and 25 for Accuspark
Not Charging
*  Brush sticking or worn
*  Wire broken off/loose inside or on terminal block
*  Commutator dirty
*  Field, Output or Half Charge fuse blown
*  Cut out not earthed
Intermittent Charging/ Low Output
*  Loose connections
*  Brushes tight or worn
*  3rd brush in wrong position
*  Switch panel problem
*  Cut out loose connections/dirty contacts/poor earth
*  Commutator dirty or oval from worn bearings
*  Field coil breaking down
*  A reverse charge shows your ammeter is reversed!
Over Charging
*  Third brush in wrong place (Typical full charge is 8-10 amps for later C35 type dynamo with 6-8 amps for earlier DFL type)
Heavy Discharge
*  Points on cut out stuck
*  A short circuit somewhere
Too Dim

*  Upgrade to 12V
*  Provide good earths especially from chassis to engine
*  Check your battery posts and clamps
*  Change to LED
*  New reflectors and bulbs Seven Workshop
Too Bright
*  Probably LED not properly in focus                                                                            
Not Rising
*  Provide extra earth
*  Lubricate solenoid post and pivots
*  Put them out before you brake!
*  Only use them to supplement modern indicators
Not Working

*  Spring on the switch
*  Make sure straight pull and lubricate
*  Connectors corroded
Not Working

*  Try to repair on/off switch
*  Use potato on the screen!
*  Use Rainex
Not On The Screen
*  Renew the spring or bend the arm

*  Try new battery after checking everything else
*  Check brushes and commutator
*  Provide good earth to chassis
*  Bad switch
*  Check cable size and make sure lugs are clean and soldered
Not Engaging
*  Low volts due battery or poor connections/earth
*  Bendix dirty
Switch Catching Fire
*  Keep switch clean which is directly under oil filler
*  For safety have a battery isolator which can be quickly reached
Locking Up
* Bendix jammed broken spring?
*  Badly worn gear starter/flywheel
From this session it is clear there are very real benefits to be had from perhaps using more modern ignition components but to try and avoid cheap Chinese copies for items such as points, condensers and rotor arms.
Providing a separate earth connection from a bellhousing bolt to a good chassis earth is a sound investment in reliability together with checking all screws in the ignition system. I would always recommend soldering battery lugs and any other terminals in the electrical system including those dreaded crimp connectors! 
With many thanks to Phil Whitter DA7C