Distributer timing

[srisant]

Hello, I have set the timing as per manual but the engine started to be misfired after 4500 rpm. Have tried advance the distributer 22deg at idle and 50deg at 3000 rpm. It runs very smooth and fine for 1-3 gear and on 4th gear over 4000 I start to hear knocking sound from engine. Can any one suggest what to do? Also I have tried reducing fuel with original spec timing and it doesn't have power beyond 3500 rpm. Many thanks

[Benz Dr.]

I set maximum advance, with all vacuum lines attached, to 38 - 40 degrees. Most distributors will reach this amount at or before 3,000 RPM. Set up this way, you should have the correct advance at idle depending on which distributor you have.
Right now, you have too much advance and your engine is pinging.

[srisant]

I have tried that setting and the engine struggle when I try to go over 4500 rpm. So I'm not sure what else is wrong. I got new and correct distributer. My mechanic said that there might be issue with the mechanic rotating parts that connect to the distributer that worn out and create too much free movement. Anyone have idea that this might be the cause?

Best,

[Benz Dr.]

Which car and what distributor are you running?

[srisant]

230sl manual.