B120dat
Does your engine not have any strange vibrations when you rev it so hard that tells you "Hoi, I am near the end"?

Dodgeman said that my engine might have these harmonic frequency at that specific revs that I said it is at(5600 to 5800).
Does balancing an engine remove these frequencies?

I am just trying to figure ou what is making this strange vibrations and maybe find a way of making it less.

Dodgeman.
I have another question.
Lets say I am driving on the freeway.
Now I must overtake a car and it is just with luck that I must go to the 5600rpm range where the harmonic frequency is.
What then?
I feel if they knew that the car gets harmonic frequency at 5600rpm they should have limited the revs to here during production at nissan those years.
OK something else.
Maybe it is mass production that causes some of them to get the harmonic frequency low and other engines at higher revs.

Dodgeman.Thanks again for your reply.
It is not many times that I send the tach to 6000.
This was my 10th time,give or take, that I have done it.
I think I must keep it max at 5500rpm.
Again, I enjoy my datsun when just cruising.
It is just that I am that kind of person,
If something is not right, I want it right or find out what is causing it.
Thanks for the replies to all.