I am not sure how to proceed on the following problem. I have a 1995 E300 diesel with a 606 series engine. I also have a parts car of the same series. The car was starting and ran ok, but after 20 minutes I was experiencing white smoke and lose of coolant. After two head gasket replacements, I decided to swap the heads. With the parts car head in place without the cams installed, I inadvertently turn the crank over with the ignition switch. I placed the crank at TDC and installed the cams. At this point the chain was too short to install the sprocket on the exhaust cam. I pulled on the chain portion that was feeding into the injector pump. It pulled a spring back and I was able to install the sprocket. I put everything back together and the car would not start. I don’t have a clear way to proceed. Any help would be appreciated.