KV6: using timing service tools

[SD1too]

Originally Posted by Bolin

Simon, I am certain that your engine would have had the belts fitted with the locking pin in and front tools engaged at the factory - so I think that as you now find that the front tools don't fit with the pin, that the timing position has moved from the original setting. Your thoughts?

I don’t know how the factory assembly worked and wouldn’t care to guess! When I have laced the new belt I will try the front tools again with the locking pin inserted and let you know what happens.

Originally Posted by Bolin

Or wear on the plastic idler or metal tensioner pulley perhaps? (much less likely I think).

With the old belt removed, I have inspected both these components.
The plastic idler wheel runs smoothly with a slight amount of play. However there is evidence on the hub of grease egress from its bearing (none found its way onto the belt).
The tensioner pulley is horrible. It runs with a worrying amount of friction and a gritty noise.
I will renew both.

Originally Posted by clf

I have been following these belt posts recently with interest and curiosity.

Thank you Alan. I am pleased that you like them.

Looking at the first image in this thread, you can see the belt 'rippled' as it sits on a sprocket.

That is my old belt and the ‘rippled’ pattern is only visual. There might be wear commensurate with 90,000 miles service but there is no abnormal physical deformation.

Then looking at the image Brian posts of a newly fitted belt, it doesnt have these depressions.

No it doesn’t have the pattern. They’re not depressions. What’s the point you’re making Alan?

Originally Posted by Bolin

Simon, did you check how much the plunger protruded before removing the tensioner bolt?

Yes, 6 mm. With the tensioner disconnected the plunger extends by 12mm. I’d say that demonstrates that my belt tension was satisfactory.

Simon

[T-Cut]

Originally Posted by kaiser

You also don't understand. And any "thinning" of the belt?
Absolute nonsense in terms of any measurable effect.

Thanks for your insight.
I was suggesting an explanation to 'slackening' belts that don't stretch, but I don't have your intimate knowledge of the KV6 timing system. What's the answer?

TC

[kaiser]

These discussions are pretty useless, because the changes we talk about are of no consequence to the operation.
Timing changes with time? yes, it might change, but with such a small amount that it is not worth even spending time on. All related to minuscule changes in the belt
There will be a small stretch of the belt, but it is virtually nothing, as you can confirm with any producer. I checked accuracy of the belts, and we are talking +-0.8mm per meter, of absolutely no significance, stretch will be in this type of order.
The effect of "wear" of the belt, and that the belt sits deeper, you can calculate it, change all the sprockets diameter with whatever you can measure has worn off, if you can measure any difference!
Add to that, that you always travel one way, and the wear will affect all parts equally and if taken up by the tensioner have virtually no net result.

And once a new belt is put on, you are back to as new, (unless you want to talk wear of the steel sprockets, which also will be insignificant.)
And no, timing inaccuracy by wear of the belt is not cumulative, it is totally and completely eliminated, once a new belt is fitted.

My argument over the years has always been that this engine is nothing different, in principle to the 1.8. Apart from the extra components and the transfer of drive from one side to the other, it is exactly the same recipe as the 1.8, and many (most!) other OHC engines. Keep the marks steady with any cam belt change, and you will be fine. Why Rover ever bothered with the floating sprockets is a mystery, it has caused untold damage to the reputation of the make, and made a straightforward job filled with mystique and superstition that is totally uncalled for.

In this particular case, we have an engine that is timed from the factory, (and the timing marks are where I said they should be), and a quick belt change would have kept all this the way it was. It pains me that some people cannot see and understand that, and it goes to show that they are no able to get a grasp of the fundamental mechanics of the system

We have a job which has been made more difficult than it should have been, and one that will carry increased risks of something going wonky after the repair.

Let's see where this ends, and take it from there.

The absolute truth and a rock solid fact is, the belt change done with marks remaining would have kept the engine as the factory sent it out.

Now if you know what you are doing, if you understand what is going on, and if you think you can do better than the factory, by aiming at a different timing, you start loosing sprockets and moving things around. It is indeed a fact, that you can improve either torque or high end power by delaying or advancing timing, and that could be of value in certain races, but most people would have no clue of what to do or where to aim.
If you believe that Rover did make an informed choice when selecting the timing they did, you leave it alone! Keep marks, change belts, job done!

If you have no particular plan or knowledge, you are wasting resources, reliability and time by touching the timing.

That is a simple fact.

[p2roverman]

Originally Posted by kaiser

Now if you know what you are doing, if you understand what is going on, and if you think you can do better than the factory, by aiming at a different timing, you start loosing sprockets and moving things around. It is indeed a fact, that you can improve either torque or high end power by delaying or advancing timing, and that could be of value in certain races, but most people would have no clue of what to do or where to aim.
If you believe that Rover did make an informed choice when selecting the timing they did, you leave it alone! Keep marks, change belts, job done!

In total agreement. Did my belts after much consulting on here - staight-forward once the principal is fully understood.

If you have the special tools then you can check the timing and correct it if significantly out (mine was).

If you don't have the tools and the engine was running OK, then DON'T slacken the front wheels, just mark them so their position is the same when the new belt goes on.

Other advice in the manuals and on here re locking the engine at the appropriate time, and locking the rear wheels when working on the camshaft end bolts applies, of course.

[xsport]

hello simon.as you have probably discovered the tools are very crude and are not in any way "accurate " as seen in their loose fitment on both sides of the camshafts but they do serve a purpose. you can also see why these camshaft ends break off when people have stressed the ends using them as a way of locking up the shaft because the could not get the rear belt tools to engage !! i wouldnt do it but there are some that would ! the main thing is that once the tools are set correctly to the camshaft fronts this then dictates the start of the cam lobes lifting positions. the rear timing marks will always be out slightly . remember that the rear belts are driven in opposite directions , from the top on one bank and from the bottom on the other. the return valve spring tensions on each cam will pull whatever backlash there is into play either one way or another to make the timing appear in some cases to be somewhat out. the main function of the rear marks is to find the mid point between the two gears to give the desired tandem effect. they are keyed to the camshaft so your never going to be even one tooth out as the belts wont fit. as long as the tools on the front have been fitted correctly to the fronts with the marks on the rear pulleys aligned inboard and the timing pin located correctly you cant go wrong. i have altered the rears in the past a little by re slackening the front pulleys a little and readjusting but maybe in hindsight they were probably better left alone as i doubt this would have been done at the factory anyway. the timing is i think never going to be spot on as too many variables can come into play but it works. i often wonder if this timing arrangement not being equal does give rise to the typical kv6 growl !! best of luck simon hope all ends well ! im sure it will. stefan.

[Mike Noc]

Originally Posted by kaiser

There will be a small stretch of the belt, but it is virtually nothing, as you can confirm with any producer. I checked accuracy of the belts, and we are talking +-0.8mm per meter, of absolutely no significance, stretch will be in this type of order.

You have given a general tolerance, not one specific to Rover.

Here's what the designer said about belt tolerance:

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.

Originally Posted by kaiser

My argument over the years has always been that this engine is nothing different, in principle to the 1.8. Apart from the extra components and the transfer of drive from one side to the other, it is exactly the same recipe as the 1.8, and many (most!) other OHC engines. Keep the marks steady with any cam belt change, and you will be fine.

Look at the length of the 1.8 belt compared to the KV6, and think about cumulative error.

Originally Posted by kaiser

Why Rover ever bothered with the floating sprockets is a mystery.

It isn't a mystery at all. Again the chap who designed the cam drive system explained it to you ages ago:

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.

Originally Posted by kaiser

In this particular case, we have an engine that is timed from the factory, (and the timing marks are where I said they should be), and a quick belt change would have kept all this the way it was. It pains me that some people cannot see and understand that, and it goes to show that they are no able to get a grasp of the fundamental mechanics of the system.

I just love the way, time and again, that you infer that everyone who disagrees with you are muppets and don't understand what is going on.

Originally Posted by kaiser

We have a job which has been made more difficult than it should have been, and one that will carry increased risks of something going wonky after the repair.

Let's see where this ends, and take it from there.

The absolute truth and a rock solid fact is, the belt change done with marks remaining would have kept the engine as the factory sent it out.

Many people disagree with you, including Terry at TS Autos, who worked at the factory and knows these cars inside out, and told you that you are wrong.

[SD1too]

Originally Posted by xsport

... the rear marks ... they are keyed to the camshaft so you’re never going to be even one tooth out as the belts wont fit.

Excellent point Stefan, thank you.

... best of luck Simon hope all ends well ! I'm sure it will.

Many thanks.

Simon

[kaiser]

Originally Posted by Mike Noc

You have given a general tolerance, not one specific to Rover.

Here's what the designer said about belt tolerance:

Look at the length of the 1.8 belt compared to the KV6, and think about cumulative error.

It isn't a mystery at all. Again the chap who designed the cam drive system explained it to you ages ago:

I just love the way, time and again, that you infer that everyone who disagrees with you are muppets and don't understand what is going on.

Many people disagree with you, including Terry at TS Autos, who worked at the factory and knows these cars inside out, and told you that you are wrong.

The logical process to disagree with my findings would be to:
1. Find a problem with my calculations
2. Find a problem with my data.

That is unfortunately not the way this world works, it seems. Just random selected quotes and no added information.

I have told you that the "alleged" designer of the belts was wrong. I told him too, and, like you, when pressed, he decided to "agree to disagree"
That is obviously the way out for people that cannot provide convincing data or calculations.

So, to humour you, I have found the following standard for cam belts and sprockets. The tolerance for a belt of our length is .43mm center to center, or if you will less than 2 mm in total length. Totally in line with my previous reference. So I think we would have to accept this as being authoritative, don't you? If not, provide some more convincing data, please.

http://www.sdp-si.com/D265/HTML/D265T063.html


This clearly blows your argument totally out of the water, and your "alleged" designer of the belt drive system is neither here nor there with his claim
"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."

The effect of this maximum expected error is in the order of 1 degree. And before you start anything, look at you clock. 1 minute on the face of that clock equals 6 degrees! Now you come and tell me that you can adjust a timing belt with an accuracy of one sixth of a minute on a dial!


If you understand what is going on, argue my data or calculations. If you don't, then use your "agree to disagree" standard clause.
And as for who might or might not agree with me, is of no concern whatsoever. If they have a problem, they can form an orderly queue.
You don't argue with physics or calculations. You find errors, - or not!

[Mike Noc]

When I get a bit of spare time I might check your calculations, but if I take them as read, and a 2mm belt length tolerance seems reasonable, you still haven't mentioned anything about belt tension, and that also has an effect on timing.

As for accuracy, I haven't seen the clearance on these tools when fitted to the sprockets, but the last cam belt I replaced was timed by pins with no timing marks at all, and as I turned all the pins down myself they were a tight fit and the timing was pretty much spot on - well inside your one degree after two revolutions.

Interestingly, the manufacturer recommended a frequency meter be used to set the belt tension, and gave no alternative, and as I didn't have one I set it by feel, so it could have been a bit out. But as both the camshaft and injector pump had floating sprockets, and the timing was set after tensioning the belt, this had no effect on the timing whatsoever.

You mentioned earlier about the timing marks being where you said they would be. Difficult to be accurate here, but when you look at Simon's first photo with the locking pin in they don't look quite lined up.

In the second photo I'd say they were nearer aligned, so whilst I keep an open mind on this, it does look like the engine isn't accurately timed when these marks align. This is backed up by the Landrover RAVE warning in six or seven different sections of the manual to ignore the timing marks being misaligned as long as the engine was timed correctly using the factory tools.

Originally Posted by SD1too

Then I discovered that with the holding tool engaged in the end of the exhaust camshaft, the holes on the inlet sprocket were not quite aligned with the pins so the tool wouldn't fit that! The engine needed to be turned clockwise by a miniscule amount. To do this the locking pin had to be removed. Looking at the alignment of the notches on the rear sprockets they must have moved closer by a small amount. This is what they looked like originally:



And AFTER the tiny adjustment:



But now the locking pin won't engage with the flywheel!

So we have to ask ourselves again, what is the definitive timing position? The rear sprocket notches or the locking pin? You can't seem to have both!

Simon

This is important if you don't now the history of the car, as the timing may be slightly out before you start. Kaiser your views are well known on these marks, but if what the designer said was correct, and the timing was still being fine tuned up to launch, then there is no reason why they would change the tooling afterwards to re-align them.

The only people it would have benefitted are the backstreet boys who wouldn't be buying the tools, so do you really think Rover would spend money just to help them? I can't see it.

[bl52krz]

I must be honest, I do not ‘get’ all the so called ‘technical’ waffling on about ‘stretch’, longitudinal wear, ‘ripple’ and everything else. It’s an ‘engine’, it reciprocating, so it wears. All that is needed is to align the timing marks, and shove the belt on. No need for any tools whatsoever. Have I ever changed belts on a 2.0/2.5 kv6 engine? No. But if I did, I would be doing it without the paraphernalia of timing tools.Never used any timing gizmo for any engine I have ‘messed’ with. Oh dear. This is a post of puzzlement, not to cause any bad feeling or antagonistic approach .