I just finished installing my cometic MHG, w/ ARP's, 550's, Lex AFM, and SP61GT. I cannot get the car to turn over. it sounds like its close, but then it just backfires. I am 99% possitive the timing is alright, because i made marks and never touched the crank.. only the cam gears and lined it up perfectly to my knowledge. Nothing moved timing wise. I dont know what the problem is, everything is installed correctly, except i broke a sensor off my water outlet housing (water temp?). That wouldnt have anything to do with it, would it? I also removed my AC, i get codes 12, 22, and 51.. i dont know if these are relative.. please help!