Hi There
I have a 1968 280SE Automatic Saloon petrol version , 6 cylinders , Engine M130 ,Chassis Number 108.018.22 018549 . Engine Number 130980.22 013780 ,Registered February 1969

I had new spark plugs fitted and changed the points but this resulted in the car back firing

To eliminate the points I had a 123 Ignition system fitted

I had the compression checked and the 4th Valve has low - zero compression

Question is what is the course of action to correct the compression problem and also stop the back firing ?
Is this linked directly to the compression issue or is their something more obvious causing this ?

All advice would be appreciated
Mark