Chinese Timing Tools

[Mike Noc]

Originally Posted by beinet1

Hi all,

I just have had a quick look at some old pictures and others found on the net. Both sprockets on the rear have notches which go in line with the key. The inlet sprocket also have a line through its center. I assume that when engine is put in "safe position", these notches shall line up through the center between the sprockets. Putting a steel ruler on the lines on the inlet sprocket and check if it mates up with the center of the exhaust sprocket can then give you an indication that the floating sprocket on the front are properly lined up or not. Does this make sense???

It makes perfect sense and that is I think what anyone would assume when looking at the timing marks - that they should align.

However, it has been mentioned before and one response given was this:

I'm sorry, but that is incorrect information.

I don't want to argue the point with you yet again so will not be making further posts in this thread, but as the designer of both the cam drive system and the setting tools, I think I have some knowledge of why the tools should be used whenever possible.

Just for information, I did issue an instruction for setting the timing without tools for use on Diplomatic Service cars. This was achieved by scribing new timing marks on the rear pulleys rather than using the existing marks. These are only there to aid positioning and to set timing between the inlet and exhaust cam. It is only coincidence that they nearly align when the engine is set to its timing position. Perhaps I should have moved the marks round a few degrees to avoid the confusion.

If I remember correctly, the fixed marks on the rear pulleys give balanced timing between the inlet and exhaust profiles. On many engines this turns out to be the optimum setting and is a good place to start. However, production tooling is frozen at least 12 months before job 1 whereas the engine tune including ignition, fuel and cam timing are subject to change right up to the wire and sometimes well beyond. The optimised setting for cam timing on the V6 turned out not to be the balanced setting, but was a little retarded (or was it advanced?) from this position and this timing figure is set by the front timing tool. It changed again for the 190 engine and this requires another setting.

The marks on the rear pulleys are still required in order to set the timing between inlet and exhaust cams. This was originally going to be a floating setting as used on the front, but it was found that we could get away with fixed pulleys (just!).

That really is about all I have to say.

Correct use of the tools also prevents damage to the camshafts while tightening the bolts as you mention.

The engine has "floating" front pulleys (not positively keyed to the cams) because there is so much tolerance build up in the cam drive system. The cams are therefore positioned by the setting tools and then the pulleys bolted up tight. Because this system was being used, the length tolerance of the belt was left very wide. If the pulleys are left in position, the new belt may well be of significantly different length to the old one. This will affect the cam timing.

In practice, you would be very unlucky to have the original belt at one end of the length tolerance and the replacement at the other so the engine will probably run OK.

The rear belts are a bit tricky with no fitting tools, but it can be done.

I would change the pump and tensioner at the same time.

You will not be able to measure the difference between the belts, just go for it and hope. Mark up the old belt against marks on the pulleys, then transfer these marks to the new belt.

You can remove the bolts for the rear belt pulleys. In fact, you will have to, but they are keyed so will go back on correctly. The problem is that the tooling puts tension on the belt before it is fitted. You could probably get round this using a wooden wedge between the pulleys or something?

Something to remember when doing up the pulley bolts - hold the camshaft at the same end as the bolt you are working on. The cam itself is not designed to react this sort of torque down its length.

And if you look at the Landrover official RAVE publication for replacing the KV6 timing belts you will find this;

Refit:
NOTE: Following front or rear timing belt
refitment, it is possible that, after rotating the
engine and positioning the crankshaft pulley to
the 'SAFE' position, the timing marks on the
rear timing gears may be misaligned. This
misalignment is acceptable provided that the
timing belt refitting procedure was carried out
correctly.


If anyone is setting their timing using the tools then perhaps they can put a straight edge across the marks afterwards and see how accurately they align?

This forum usually comes up with the correct technical information once everything has been kicked about, and it would be good to get a definitive answer to this one.

[kaiser]

My God!
We need another bucket of pop corn!

[beinet1]

Thanks Mike,

This clears up a few questions and rumors Makes sense to me.

[marinabrian]

I'm jolly glad I have a set of the factory tools for this job, no guesswork needed

[SideValve]

Fascinating discussion. Almost wish I had a spare engine lying about to play with.

In the mean time, I've only done 4 cylinder engines and have just lined the marks up. It seems sensible to me that a V6 would also involve lining up the rear marks then, presuming the crank is where it should be, doing up that end.
However I can appreciate that timing might not be 100% optimal and that varying it might produce better results especially when running non-standard exhausts or inlets.
I've not seen what these tools provide. If you use them what do they let you vary inlet vs exhaust or inlet & exhaust vs the crank? And what is the process? I've tried it on old bikes using discs to identify degrees past where the valves start to open/close but that's easy to spot on 350 single....
Just idle interest but I'd be interested to know the answer.

[Mike Noc]

Originally Posted by SideValve

I've not seen what these tools provide. If you use them what do they let you vary inlet vs exhaust or inlet & exhaust vs the crank? And what is the process?

The tools will lock the two camshafts driven from the front belt in the correct timing position, and pin the crankshaft in the correct timing position.

This allows you to set the tension for the front belt independently of the timing, and when you have the tension correct you can tighten the two front floating sprockets to the camshafts.

As well as locking the camshafts in the correct position, they also allow you tighten the holding bolts safely - if you don't use them and put a spanner on the other end of the camshaft you risk snapping it.











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