okay so i have been working on this thing for over two months now. I originally was only going to change the timing belt on my 2009 Subaru outback. I changed it and put everything back together but it wouldn't start. I took it back apart and changed the valves because they were bent, and changed the head gaskets, exhaust gaskets, intake gaskets, and the spark plugs. I put it back together and lined the timing marks and now it will not start it only backfires... it will crank but it doesn't fully start just backfires.