945 Niggles

[Laird Scooby]

A weird thought crossed my mind while reading your latest post Rick. If memory serves correctly the starter motor is on the drivers side of the engine on the B230 and the main earth from battery to engine is on the starter motor.

I'm wondering if perhaps that earth connection has either come loose, broken in the crimp terminal or nearby it and under normal circumstances still makes the circuit. However, on the over-run, the engine would naturally tip slightly towards the passenger side which may be just enough to break the connection. This could be made worse if the drivers side engine mount is loose, worn, broken or otherwise not doing its job.

All the evidence is pointing to something like this unless i've misunderstood what you've said about the rev counter - it would also occur going over level crossings that are bumpy or any other sudden change in speed including letting go of the loud pedal and sometimes even through normal road vibration.
Worth checking the earths anyway and also the lead that goes into the distributor for the signal to fire the coil - i had a break in one of the wires on one of mine but can't remember which where the cable went into the dizzy. Someone had refitted it incorrectly so it wasn't held into the dizzy properly so chafed the wiring.