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Old 12th September 2015, 23:50   #11
Stag>75
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Quote:
Originally Posted by Phil-T4 View Post
Sorry but the front inlet cam pulley is keyed to the camshaft!
What I wrote was "The front sprockets are NOT "keyed" to the camshafts like the rear ones are"

And they are not.

As I read it the OP was wanting to understand how moving the front sprocket with the timing tool would impact on the rear sprockets. The fact that the front sprockets are not keyed to the camshaft but float on a hub is in my view the critical thing for the OP to understand.

To the OP, I hope that you have the answer you were seeking.
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Old 13th September 2015, 15:20   #12
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Thank you all for your input on the matter.

Quote:
Originally Posted by Stag>75 View Post
[...]part of the tool inserts into the front of the ecxhaust camshaft. If you want to guarantee alignment there is no other way than to use the special tool, here is no reference point that can be relied upon.
I know the front sprockets when unbolted can turn a bit on the camshaft.
The timing is done on the front and the tool is actually holding the camshaft itself, not the sprocket (when unbolted ofcourse). The small freedom of the sprocket rotation is used to fine tune the position of the sprocket in regard of the teeth of the tensioned belt and therefore the crankshaft.

The above leads to the conclusion that the timing - a correct positioning of the camshaft is done by the tool. The tool is rotating the cam to the correct angle and holding it there while you put on the belt. The different tool plates (2.0L, 2.5L, 2.5L 190) rotate and hold the camshaft to different angles.

The main question turns out to be: if a correct 190 tool plate is used, what is the position of the rear sprockets? Will they align? What if a wrong tool is used?

I'm sure this is true for standard 2.5L as Phil-T4 wrote, but is this also true for the 190 when the cam is rotated to the degree dictated by the tool?

If this will be confirmed it would mean, for all engine versions in perfect timing the marks on the rear sprockets align, and taking into account that the marks will align at only one specific camshaft angle, then it would seem that even when no tools were used and the mechanic simply checked the rear sprocket marks alignment, then the correct camshaft angle was set - no matter if it is a 2.0 or a 190.

Another question: I've read on this forum that "on the 190 the timing is different on the rear bank". What's that all about?
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Old 13th September 2015, 17:08   #13
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Quote:
Originally Posted by slav View Post


[B]The main question turns out to be: if a correct 190 tool plate is used, what is the position of the rear sprockets? Will they align? What if a wrong tool is
As said , there are 3 camshafts used in the v6 for the 2.0, the 2.5 and the 190 variant . Each is timed at a different angle relative to the crankshaft , but so long as the correct plate is used at the front then it will set the camshaft at the correct angle and the marks at the rear will line up . If the wrong plate is used , then I would not expect the marks at the rear to line up ( never tried it ! ). So long as the engine is timed correctly to start with , then so long as you do not loosen the sprocket hubs then it should be able to go back in the same position without using the setting tools If you are in doubt about the setting to start with you should still be able to trust the marks at the rear so long as no-one has fitted a different head , changed camshafts or otherwise tinkered with it !
As I understand it , the purpose of the floating hub in the sprockets is to allow the teeth to be aligned with the belt and permit some movement of the sprocket when the belt is tensioned , while the camshaft is all the time held correctly by the tool. As I said before , it is quite clever in use
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Old 13th September 2015, 18:01   #14
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Blimey Im glad I bumped this question

After reading all the comments I now have a better understanding. As the OP said thanks to everyone for their comments. I sit in the no need for the timing tools side of the garden but we will see when I do the job
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Old 14th September 2015, 11:01   #15
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I am afraid that simply aligning the marks on the rears when in safe position is ok to make the timing work but is not enough to get the full power form the engine.

I managed to dig up a post from the other site by the user 1955diesel who worked at Rover and designend the timing mechanism. Our member Kaiser discussed the issue of the rear marks with him:

Quote:
Originally Posted by Kaiser
In short. Your engine is perfectly timed if the clear marks on the rear sprockets are in line when the engine is in safe mode.
End of story.
Quote:
Originally Posted by 1955diesel
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.

Correct use of the tools also prevents damage to the camshafts while tightening the bolts as you mention.
End of story.
Quote:
Originally Posted by 1955diesel
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.
To sum things up:
To align the inlet cam to the exhaust cam, you use the rear sprocket markings. This assures that one cam angle is synchronised to the other cam angle and that's what rear marks are for.

But to do the actual timing - aligning the cams to the crankshaft in most accurate way, you unfortuanatelly need the tools to do so.

You can get away with just setting the marks on rear sprockets to align when in safe position and the engine will work fine as this is the balanced setting and is perfectly fine to make the engine work correctly.

If however you wish to take advantage of the research done by the factory in fine tuning the position of the specific cam you have and therefore get the full power available with that cam, use the tool to set the cam to the proper angle when cranshaft in safe position.
This is the only way to know what is the best angle for the camshaft you have.
Unless ofcourse someone with the tools () can attach them to the cams on the front and make a detailed documentatin of the angles of the marks on the rear for each engine version, then peopople without the tools could set the same angles. Untill then, tools it is.
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Last edited by slav; 14th September 2015 at 11:07..
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Old 14th September 2015, 22:02   #16
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I firmly believe (but have no proof) that the inlet cam needs advancing around 10 degrees to improve torque on the 190. The reasonfor saying this is the inlet valve on the 190 opens at tdc - this is just about unheard of on anything other than lawnmowers. I belive it was done to improve emissions for the 190 with the increased valve timing.
Also, as further evidence, look at the 16v k series, closely related in many ways, again opens the inlet valve earlier. Usually, advancing an inlet cam will, up to a point improve midrange torque, at the expense of top end bhp. And who needs 190 bhp anyway? Its only there as a sales gimic, in my opinion.
There is one possible fly in my theoretical ointment however, the poorly designed exhaust front pipe, it may be that the back pressure from this could reduce the effect of increasing overlap, but its a slim chance.
Also, the ehaust timing would need to be adjusted to keep it where it is.
Huw
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Old 15th September 2015, 01:17   #17
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If you know your engines, you will also know there is not one set timing that is best. There is a timing recommended from the factory, which according to them provide the best compromise.
I remember my discussion with that person, and I also remember he opted out on several occasions.
He might have designed the system, but he did not strike me as being fully aware of what was going on. But, as they say: De mortuis nihil nisi bonum

So to sum up. There is no chance in hell that the marks align by chance when the right timing is done. It is designed like that, and that is common for any engine produced I have ever come across. The timing is on, when two or more marks align.
The problem is, if that is the case for all models of the engine.
That answer can perhaps be answered by researching if there are different parts numbers for the sprockets for the different models. If so, the only difference could well be the position of the marks.

It does not take much to provide the correct marks when manufacturing, but it introduces more numbers and spare parts.

They could simply have made several marks and marked them clearly, and the problem would be sorted, but this is the logical choice. That seldom seemed to be what Rover did.
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Old 17th September 2015, 22:40   #18
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Maybe the keyway's in the cams are counter rotated the same degree as they are advanced at the front on the 190? i dont know but it would enable all pulleys to be the same across all engines.
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Old 18th September 2015, 11:27   #19
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Originally Posted by Lozzer View Post
Maybe the keyway's in the cams are counter rotated the same degree as they are advanced at the front on the 190? i dont know but it would enable all pulleys to be the same across all engines.
I suspect you are right ; the setting is in the camshafts
As far as I know , the sprocket wheels are all the same .
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