My KV6 Cambelt change

[p2roverman]

Problem solved at last, thanks to everyone's input.

With better light today and belated look at Rimmer's drawings and Beinet's post, I realise that the two holes the front locking tools lock into are in a loose 'camshaft hub' which is keyed to the camshaft, not in the chainwheel itself. I had mistaken thought the tool locked the chainwheel, not realising the existance of the separate hub.

This answers all my questions and makes the job of fitting the belts and correctly timing the engine straight-forward, even if not simple.

And of course the reason why I could not get the front tool to engage with the engine in 'safe' position is because the valve timing is out by about 5 camshaft degrees from when the job was last done before my ownership. This probably explains the car's poor performance compare with the 'spare' car I'm currently driving.

[p2roverman]

Originally Posted by kaiser

Of course the rear marks can be made to align perfectly! And if that is the correct setting (which I seriously believe it is), could have been found out this time, as the OP had a factory set engine, and could have verified this with a photograph.
It still can be found out, if you believe the special tools, because if the tools are fitted, where are the marks?
Take a photo and let us see!

That Diesel 1956 comes with a statement of pre-production delays is absolute nonsense. Once the correct timing is established for the engine, it is possible to make correct marks very easily, for Pete's sake, we are talking about two dimples, or marks, that is all. You don't need 12 months to make that. You can scribe this unto the sprockets when you assemble, if need be.


I think we are discussing with a bunch of people many of whom really do not understand how an engine works.

And for people that quote and paste or refer to information, give a link so people can go and read the whole story, don't just quote selectively.

Kaiser - You'll read that my initial problem was due to me not realising until now that the front locking tools engaged a loose hub keyed to the camshaft (it looked to me that the tool engaged the actual pulley). Now the job is straight-forward.

As to alignment of the marks on the rear chainwheels when the engine is in safe mode, if they do, by chance, line up when the 2-litre tool is used, they won't line up when the 2.5 tool is used, or vice-versa; but it doesn't matter so long as inlet and exhaust cams are in the correct relationship. (This statement assumes that the same camshafts are used on both engines, I haven't checked.)

Oh, and thanks for all your advice on this issue. Once I've finished the job on this first car, the others will be dead easy.

[kaiser]

[p2roverman]

Originally Posted by kaiser

I have, of course, locked the engine with this pin.

New main belt now fitted (front chainwheels loose on camshafts, with both camshafts locked with the special tools, using the 2-litre pegs). Tensioner in place, but job on hold as need new bolts for this because the heads have been chewed up, making torquing up and later undoing doubtful.

I suspect the 2.5 litre tools may been used last time which is why nothing would initially allign. Now to check if it's had a 2.5 engine fitted sometime before finally torquing up the camshaft bolts.

[Mike Noc]

Kaiser as the camshafts rotate at half crankshaft speed you need to ensure the timing isn't 180 degrees out, so that is what they are explaining there.











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[p2roverman]

Originally Posted by Mike Noc

Kaiser as the camshafts rotate at half crankshaft speed you need to ensure the timing isn't 180 degrees out, so that is what they are explaining there.

I'm aware of this of course. However, there were paint marks on the chainwheels from when the job had been done previously so I didn't need to check further.

Although on thinking about it, one cannot get this wrong as the camshaft front tools will obviously not fit (by 180 degrees).

(The fact that while doing this job one of the marks rubbed off was not an issue as the front tool will bring the camshaft to the correct position. However I did note that 'freewheeling' motion of the chainwheel was limited, whether this is by design or the tool 'pegs' protruding beyond the loose hub I didn't check. However, it will pay to check that there is sufficient rotational movement while placing the belt.)

[p2roverman]

Originally Posted by p2roverman

As to alignment of the marks on the rear chainwheels when the engine is in safe mode, if they do, by chance, line up when the 2-litre tool is used, they won't line up when the 2.5 tool is used, or vice-versa; but it doesn't matter so long as inlet and exhaust cams are in the correct relationship. (This statement assumes that the same camshafts are used on both engines, I haven't checked.)

Since found at least three different sets of camshafts, so these are presumably machined so that the marks on the rear chainwheels (common to all models) are in allignment when the appropriate front tools are in place.

Rather odd that Rimmers list camshafts for the Rover 75 2-litre, MG 160 & 177. and MG 180 & 190. No mention of the Rover 75 2.5 litre.

[kaiser]

Originally Posted by Mike Noc

Kaiser as the camshafts rotate at half crankshaft speed you need to ensure the timing isn't 180 degrees out, so that is what they are explaining there.

.

This is again a quick response with insufficient thinking to back it up, I'm afraid.


But argue your point and tell me how four marks on two sets of sprockets can tell you if you are out by 180 degrees!

There is no further information except 4 marks that can align. They will do that every 180 degrees turn of the camshaft!, so that is alignment for each full turn of the crank.

That is never going to tell you if you are 180 degrees out.
These are timing marks for the cam, like they appear on almost any normal engine.
And THAT is what that page describes. And that is exactly what it says in plain English!



















.[/QUOTE]

[p2roverman]

Originally Posted by kaiser

This is again a quick response with insufficient thinking to back it up, I'm afraid.


But argue your point and tell me how four marks on two sets of sprockets can tell you if you are out by 180 degrees!

There is no further information except 4 marks that can align. They will do that every 180 degrees turn of the camshaft!, so that is alignment for each full turn of the crank.

That is never going to tell you if you are 180 degrees out.
These are timing marks for the cam, like they appear on almost any normal engine.
And THAT is what that page describes. And that is exactly what it says in plain English!
.

Kaiser - I agree.

In my case, as mentioned, there were paint marks already on the front wheels from a previous time so getting it right was easy.

But I also checked the rear wheels, and while it is possible to allign the marks with the timing 180 degrees out from where you want to be, the marks are not all the same, one on each wheel being notch as well as a scribed line. Looking closely at drawings / photos in the manuals will show which way the marks should be lined up.

Incidently, are you still doing the ally thermostats? I've two so far, but may well ressurrect the unique Arden Green 2.5 Club SE tourer, which might as well have one fitted when I do its belt change - yet another car I have with no history.

[kaiser]

It is dead easy, if you don't assemble the engine from a box, it has been running and the marks can't be out by more than maybe two teeth on this engine before you get interference.

It is just completely insignificant if you time at 180 or 360 degrees! The alignment is perfect in both cases, when the safe mark aligns with the four marks on the rear sprockets!

And that is that!