Due to the appearance of the spark plugs and other factors, it was pretty safe to assume that cylinder 3 (at the very front) did not run. Thus, the respective contact breaker for cylinder 3 was changed. It was easy work: To get out the old contact breaker its cover was opened, the contact tab loosened and finally the whole contact breaker was unscrewed from the base plate. After slightly enlarging the mounting space by filing the adjusting screw, the mounting of the new contact breaker was straight forward too. Afterwards the ignition needed to be adjusted and, using a dial gauge, this was also expected to be an easy step. Accordingly, adjusting the opening angle of the top dead center (0.4 mm) for all three cylinders was not a problem. However, it was not possible to adjust the opening time since the extension for the gauge was not long enough (by approx. 1.5 mm). So the only option remaining was to hope that adjusting the opening angle was enough. The motor was started for a trial run and lo and behold:
Naturally, this success caused a lot of satisfaction and happiness!
So everything was reassembled without further ado (mounting of the front mask, fastening of the Bowden cables, repairing the lights) and a first test drive followed.
Well, the happiness did not really last long....after approx. 35 km the backfiring was starting again. Luckily, the car made it somehow back home and we did not need to call again the ADAC ( German automobile club providing emergency aid). Nevertheless, the frustration was yet again quite big!
As it turned out the newly installed interrupter lever was broken which of course completely messed up the timing for ignition.
So repair the second round and hoping that the happiness about a running car is longer lasting this time.