I recently purchased a 1982 240 D Mercedes. It was already set up for Bio- Diesel and Vegi oil. The cylinder head had been off and the timing was incorrect. The lady I got it from was told that there were no timing marks so they had to make some. That being said I started disasembly. I found the cam to be 45 Degrease out of time. Now my problem. When attempting to bring the engine to Top Dead Center on #1 cylinder, the piston comes in contact with the valves on #4 cylinder because of the overlap on the exhaust stroke holds the valve open slightly. I ran into this same senario 30 years ago and I cant remember what we had to do. Since I seen it before I know its not a new problem. What am I overlooking here? I can only bring the piston within 10 degrease of TDC with valves butterflyed and mark lined up. H E L P!!!!