ummm narh no vibrations, but mine has been fully balanced which does help. but no vibratins. when i first put my motor in and home did the talishaft weld etc vibrated and shook the car badly, but after a reweld and balance it was fine

I think that there is something wrong with your engine, & the other questions can wait untill you confirm that the flywheel is not the problem. If it is "chattering" at these speeds, you will get symptoms like you describe.
These harmonic frequencies occurr in ALL engines, but with everything done up tight, you do not normally feel them.

Lay off the lead boot untill you can check everything out.

Dodgeman.
I feel to disagree with you.
Me and my dad overhauled the engine 20 000 to 30 000km ago.
I know we did it the right way as we used a datsun manual.Page by page.
The crank was not removed.Only head and pistons and conrods.
I feel 80 to 90% sure it is the engine's harmonic frequency that we talked about and that the flywheel is maybe out of balance.
If it was the engine it would have made rattles and noises.
I had the window down to make sure it did'nt make noises.
No noises were heard.
I am going to sort out the flywheel and then see if it helps.
I will also ask the mechanic to make sure everything is 100% correct and that I want to come and check things out first before it is assembled.
Thanks for the replies.
It helped me to look at the problem from all angles.

The redline of a stock A12 is 6000 rpm, and of A12GX, 6600 rpm. My first A12 (totally stock [edit: except weber carb]) revved to 6000 rpm all day long w/o any vibrations. The rings wore out fairly quickly, so I don't do that anymore ...

With mass production, it is possible that some A12s are out of balance enough to cause unexpected vibrations.

Check you engine mounts, Gearbox mounts and exhorst mounts and alt brackets etc. Test and tighten all the nuts and bolts you can find and reach. Every time I take my race car out I do this. lots of things in a datto will rattle and clunck and your always sure its the engine. Try and eliminate all other possabilities. It will be easier than taking the flywheel off and if its not the problem at least you'll know everything else is nice and tight.

Quinn

Quote:

Then why did my factory built 150,000mi A12 (original engine) VB110 Wagon used to redline (stop revving in 4th) at 6600rpm.

This was a digital (CRO calibrated) digital Tacho?

I've been waiting for days to throw in this snippit

Before you all ask..The "Blue Thunder" dissolved into a cloud of Blue smoke about 50,000mi later Was succeeded by a late model A14.

Quote:Good question.

Redline is not the absolute rpm the engine will run at, nor is it the rpm the the car can do in top gear. Redline is the manufacturer's stated limit for "safe" operation.

White line - normal operating range.
Yellow line - maximum engine speed. Do not keep in yellow continuously.
Redline - maximum engine speed. Should not be exceeded in any circumstance by a stock engine.

These stock operating limits are approximate due to the errors inherent in tachometers. If you get a tacho calibrated you will notice it can be correct at one speed (say 8000) but be 400 rpm out at 4000 rpm.

To raise stock engine speed limits requires engine balancing, component lightening and valve spring/retainer/rocker upgrading.

To actually get the engine to be able to use the increased engine speed range (as B120 Dat mentioned) a camshaft change, ignition upgrade and a suitable fuel supply is needed.

I have also had the pleasure of a near stock 1200 that would run to 6600 in top gear. It was getting valve bounce at this speed : )

The car was great fun, especially commutting from Queenstown to Burnie in Tasmania via the Tyndals road to Tullah. If you ever get a chance to do this drive in a 1200, it is a must. In fact the whole of Tassie is 1200 country

I was of course quoting my younger more silly days when quoting the "valve bouncing incident"...back in the day when an unprotected council park was a doughnut pad and spares were plentiful.. "..please take me home" (Guns and Roses).

Thanks for the tip. I'm planning to do the "Spirit of Tasmania" cruise to Tasmania in my "GTR-110" project 1200 when it's completed. Then do some of the more famous drives around Tasmania. It's like having our own New Zealand..Both are beautiful places (residents sometimes excluded).

From Sydney for $440 twin share, you and your car get a cruise to Tasmania including return dinner and a brunch. The advantage is, I wouldn't have to waste my time driving some of NSW's terrible roads.

In my drive to Adelaide I noticed the roads of Victoria and South Australia to be far superior to NSW.

Chris

Chris,
You are in for a treat. The roads really are fun and can get very busy all of a sudden.

I travelled from Hobart to Queenstown in November and managed to burn out a set of rear pads over Mt Arrowsmith due to an excessivly soft compound. The material overheated and just fell apart!

Good brakes and good suspension coupled with Tassie's good roads (mostly) and the scenery makes for a good time. West Coast roads are my favourite but they need to be treated with respect!

You will have a ball, I am jealous