Previously I had troubles with a timing chain replacement , but now , with the engine ( 617 ) re-timed , I am replacing the rocker arm assemblies that were removed to allow re-timing the camshaft . The front rockers went back on with little difficulty but the back group of three are proving a problem . I did a search for threads on this and found nothing . I tightened up the valve adjusters to try and give as much clearance as possible but the rockers just don't seem to want to go back in and I don't want to use too much force .