Okay here is my problem. I changed a bad engine out of a 97 blazer - 4.3 engine with another 4.3 engine that is only 6 months old and has less then 20,000 miles on it. I had taken the distributer out and tried to find the top end of piston 1 with the factory timing mark and that was no good. Tried to set the piston at top end and set the distributer to fire on the number one piston. No luck. And yes I did unplug the distributer but was told that it didn't matter I had to find another plug that deals with the timing and the computer. It does start up and runs but sounds like all the rods are knocking. It also has oil pressure. I personally would take this @#! thing to scrap yard because it has to be the most time consumeing car I have ever worked on. Please and thing HELPS !!!!!!!!