Hi Mr Pete, could you please explain a little more about this practice? Like Aircool, I am about to assemble a 77' T140 engine but just don't quite get the 'ball business'.The first thing you need to get right is the large washers on the 3/8" inner head studs.They should be the same diameter (same part) as the washers on outer head bolts.If you have the small washers,they will keep crushing into the head and losing bolt tension (especially the exhaust side).
Fit those studs upside down (turned end down),with a 1/4" ball under each stud.Don't tighten the studs tightly onto the ball (about 1 or 2 ft-lbs).
You should have no trouble torquing/re-torquing the allen head nuts on those studs.I use a piece of allen key fitted into a single-hex socket.
It's normal to just guess on the cylinder base studs,and just make them tight.The nuts on the 3/8" studs should be 35 ft-lbs.I can't find any mention of torque on the outer studs with 5/16" threads.I've seen them broken,and wouldn't use much more than 20 ft-lbs.
You should back off each cylinder head bolt slightly,just enough to move the thread,before you re-torque it.Otherwise,the "stiction" will give a false reading.
Many thanks. Can understand the move now.As the studs are originally fitted,most of the load on the barrel thread is taken near the cylinder head face where the stud fits tightest.
When you tighten the top nut on the stud,it pulls the barrel face out of shape around the tapped holes.The metal gets pulled upward,so the face isn't flat.The high local load also forces metal sideways,distorting the top of the cylinder.
Upside down with the ball underneath,the shank of the stud doesn't wedge against the barrel face.The load is spread more evenly over the threads in the barrel,instead of being concentrated near the barrel face.
The head gasket seals better on a flat barrel face,and the cylinder stays more round.