my bad... To be honest i was one of the unluck few that doesnt have a tachometer with my dash.

5,500rpm saw me out in my GX engine. It could rev more, but i dont abuse my engines & this one rewarded me with spirited performance & long life. It was a fair deal.

If the flywheel is less than fully tensioned, the harmonic frequencies at critical rpm's cause it to "chatter" This damages the six little bolts & the problem just deteriorates untill all six bolts break. It also messes up the flywheel & can hurt the crank too.
Many "A" engine racers have learned this the hard way.

The embarrasment of having it towed home will be relived every time one of your friends with a Toyopet reminds you of it.
[Toyopet became Toyot..aargh.]

The chances of it being a timing chain is probably somewhere between slim & none.

Try your best to get a tach.
It helps alot if you want to know what you are doing.
Revving hard or just driving economicaly.
(Excuse the spelling)

mine revs to 6400 buts it screaming its tits off and i dont do it outta habbit, chirps into third gear when i do though, sounds so loud, going round a corner she'll hit 7500-8000 regularly (rallying, i.e. on dirt)

Dodgeman.

I think you answered my question on the strange vibrasion at 5500 to 5800 rpm!!

I think it IS the engine's harmonic frequencies.
Why I say that and please correct me if I am wrong.
It only is in the range of 5500 to 5800 and then it goes away and that strange oval feeling comes from the gear lever.

My questions then is: How does the other guys get 7 to 8000rpm out of their engines!!
Will balancing it remove these harmonic frequency?
Not that I am going to do it, just curious.

My clutch is going to be removed soon.
I am then going to lighten my flywheel.
Will balancing help with these strange vibrations?
I think I am then also going to let them replace all bolts holding the flywheel.Just to be safe.

yeah mine revs to 8000rpm, and it just wants floggin all day it isnt happy with me changing early lol loves the revs!

Ok seriously. I want to join the high revs club! what the hell do i have to do to get my car to do that?

good cam and a set of webers never hurts

1200GXman
Don't just tighten the flywheel,.. remove it. While it's off, carefully examine the inside of the flywheel where it touches the crank, all six bolts, & the crank itself. Check the fit of the flywheel on the crank. There should be no looseness.

If you are completely satisfied that everything is OK, then refit it & tighten it.
If it HAS been moving, the bolts may be damaged & retensioning them without first checking them could be bad news.
If they ARE damaged, & you are lucky, then one or more will break while you tension it. If you are NOT lucky, the damaged bolts will not break untill after you have it back on the road.

Before refitting the bolts, make sure that the holes, & bolts, are sterile clean, then use a little of the correct grade of Locktite on them & do them up FT [the "T" is for tight], check the manual for correct specs.
My workshop manuals say 54 ft/lbs [1200] & 61ft/lbs [120Y] I seem to remember that with new bolts, i went a bit tighter than that. The number 70 seems to ring a bell, but don't quote me.

I can not nominate the rpm's where these harmonic frequencies are at their worst, but race engines suffer this problem most, so it would be in the higher range without doubt.
I would highly recomend that you educate your right foot untill after you have pulled it down for inspection & repair.

Balancing of the whole rotating, & reciprocating mass, including the clutch pressure plate, is HIGHLY RECOMENDED for ANY engine that will regularly visit the higher rev range.
Good luck
Chris
P.S.
A harmonic ballancer will help this problem, but there are none available for A series engines. My mate with the injected A15 in his 1200 coupe racer has shed a couple of flywheels, so he adapted a falcon six balancer. It isn't pretty, but he hasn't shed a flywheel since, & this thing gets hammered hard enough to win the season championchip,....again.

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.