[slav]

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:

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.

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.

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.