400 - “elasticity” in headnuts

[K2-K6]

A question to the OP, can you turn the nuts with your fingers when they are not torqued/tightened ? In other words can you twist them down with your fingers easily until they touch the washer and then just needing to be tightened with a socket from there ?

Thinking we may have interpreted the description of "elasticity" wrongly. If they are tight right from putting the nut on the stud then that will give a torque requirement without even clamping the head sufficiently to start with.

Thinking out loud really as they should stay tight once assembled with no real problem. 

Are they the original nuts that are in use too ?

[Erwin83]

At the risk of sounding daft I have felt this sensation decades ago when tightening Helicoiled threads back in the early days of Helicoils.

Are all the head stud threads in the block as per original ?

OK, I did not think of that before. I'm using Bell Ray EXL 10w40 (mineral). Should I move to another oil type?
I was not planning on putting on oil cooler on this bike to be honest...

[Erwin83]

At the risk of sounding daft I have felt this sensation decades ago when tightening Helicoiled threads back in the early days of Helicoils.

Are all the head stud threads in the block as per original ?

Yes, the studs have never been removed from this block. Also did not come loose accidentily when undoing the head.

A question to the OP, can you turn the nuts with your fingers when they are not torqued/tightened ? In other words can you twist them down with your fingers easily until they touch the washer and then just needing to be tightened with a socket from there ?

Thinking we may have interpreted the description of "elasticity" wrongly. If they are tight right from putting the nut on the stud then that will give a torque requirement without even clamping the head sufficiently to start with.

Thinking out loud really as they should stay tight once assembled with no real problem. 

Are they the original nuts that are in use too ?

Yes, I'm using original nuts, although I may have mixed up some 350 / 400 parts as I have been working on both these engines simultaneously for years.
All the nuts go on smoothly. I normally use a long socket to place the nuts and reduce the chance of the nuts falling in. They all feel normal when turning them the first couple windings with my fingers on the socket.

[Erwin83]

Runs fine now, have not seen even a puff of smoke.

https://youtube.com/shorts/v9xFpDdq0PY?feature=share

[McCabe-Thiele (Ted)]

Runs fine now, have not seen even a puff of smoke.

https://youtube.com/shorts/v9xFpDdq0PY?feature=share

So how did you fix it or have I missed the cure?

[Erwin83]

I retorqued the headnuts and placed one extra ring under the one nut that I found 'loose' again. Idea was that maybe the tread on the one with the most elasticity was not perfect and the extra nut ensures the use of cleaner thread. Or if the nut bottomed out, the extra ring gives more space and makes sure the nut clamps down on the head for sure.
In any case, the elasticity is now gone...

I have not taken the head off. Just retorqued with the head in place.