E30 320 ignition timing

I have a 1987 320i with an ignition timing problem. I initially thought that its timing was 100% electronic, but it can be advanced/retarded by
turning the distributor. The problem is that it PINGs often when cold. It also sometimes pre-ignites while you are trying to start it. It would sound like a dead battery and then it will start swinging normally.
How do I check the timing to be in the right position? As far as I know, there is no mark on the pulley.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.