lets talk about m110 ignition timing

[350SE BENZ]

To start of iam going to say that when it comes to ignition timing iam not very knowledgeble. I own a w116 280s Euro model, i say it is a euro model becuase i am from south africa and the car was bought new here, in other words the car was manufactured here in South africa.

It has the standard Solex 4a1 carb, wich is still in perfect condition, the ignition system however doen not appear to be standard. There is no ICU nor white ignition ballasts, these were removed by the previous owner. In there place the guy fitted the car with a ordanary coil, and inside the distrubutor has a points and condenser set up. The piont is connected to the (-) side of the coil. There is no ballast in the system. The system works, but what implications can this have?

The problem i have is when i set the timing at 4500rpm with the vacuum disconnected at 28 degrees BTDC, and i reconnect the vacuum it advances to 52 degrees. In other words an advance of 24degrees, i know that the advance shouold be around 12 degrees, what can cuase this over advance?

i have set the dwell to 39degrees.