Thanks for the replies guys, iv sused it out now, and sheltie 50 your right its the detent screws. I now have much bigger problems though, the bolt that locks the cam sprocket to the cam came loose and bent all the valves. I changed the valves lapped them all in new head gasket, bolts etc. replaced everything top end timed it correctly and now it wont start, i have checked the pump timing and that is correct but it will not fire up