My friend has a MK 2 Volkswagen golf with a MK 3 2.0L SOHC engine swapped in it and it runs of a charge distributor. He complains about having timing issues after a mechanic twisted his charge distributor a couple of times with sometimes the red line of the engine randomly moving to only 5K and sometimes 7k without a warning. He says when it redlines at 5K he can feel the engine becoming more responsive.
I tried to look at a mark at the crank pulley to adjust the timing with my timing light but could not find anything. How can the timing be adjusted on such engine?
Edit: trying to rephrase this question, how can you tell at which angle is the spark firing in old cars with distributor rotor