Valve timing fine adjustment

[GrimV8]

I think everyone does that with the tensioner once, it's like the apprentice initiation of Rovers

I haven't
If you have the head off you can fit the tensioner to the head before re-fitting the head.

Head off, you been polishing your piston tops again?

I haven't either TBH but it's a common thing to do if you've never been taught

 

[herts2000]

i must say my p6 is coming together nicely will bring it along to the cambs meet soon :wink:

 

[esray]

Harveyp6, Grimv8, where is and how do I access this vernier, please? I understand from your threads that I need to back off the top tensioner, but what then? Can I get at it with just the rocker cover off? Is it accessible through the timing chain top tensioner cover on the front of the timing chest? Truth is, there is no mention of either a timing chain sprocket or a vernier in Haynes, so I have no idea what I am looking for, or (for that matter) what it looks like! :?:

 

[redrover]

Give me a tick- I'll do you an exploded drawing. There is a general camshaft diagram in the rover issue workshop manual, but I think this discussion would probably benefit from a close-up one.

Michael

 

[redrover]

Right, I've attached a few exploded diagrams to show where everything is. (It's deliberately massive so you can download it )

Diagram key:
* - Securing nut for use when mounting it to the 'smiley face' support bracket. You will need to obtain one of these - one of the nuts on the steering idler bracket behind the carbs will do ideally in the short term
A - 'Smiley Face' Steel support bracket
B - Vernier set bolts
C - Lock-tab
D - Circlip. Sits into the first groove of the chainwheel (F)
E - Vernier assembly. Teeth on the rear side engage with inner groove of chainwheel.
F - Chain wheel

G - Chain tensioner adjustment access hatch.
H - 4mm Allen key and small 7/16 AF socket needed to back off chain adjuster.
I - Round inspection hatch. Useful for slotting in a thin piece of wood to prevent chain tensioner pad springing out into the sump when working on the chain wheel above. Take care prising the alloy cover out - it will chip! Use two blunt screw drivers with cloths around them to lever it out.
J - 'Smily face' steel support bracket
K - Vernier assembly and chain wheel complete.

L - Camshaft
M - Camshaft flange. Set bolts (B) bolt into this flange through chainwheel.
N - Chainwheel (F)
O - Vernier assembly complete (E)
P - 'Smily face' steel support bracket (A)
Q - Securing nut (*)

Aside from the chain tensioner inspection hatches, you only need to remove the rocker cover (3x 1/2 AF bolts) to gain access.

As mentioned elsewhere, the trick is to back off the set bolts until they are just held in by one or two turns (as shown in the bottom diagram). Pull the vernier assembly (E) forwards and tie it to the steel support bracket with the securing nut. Then push the chainwheel backwards over the camshaft flange (M) (Gap between O & N in picture is bigger than reality). Provided the camshaft is locked in the correct position, all you need to do is place pressure on the left (non driven - rotation is clockwise) side of the chain (where the arrows are) to rotate the chainwheel as far as it will move. Then push the vernier back into the centre. The vernier teeth will start to grip. Screw the set bolts (B) in as far as they can go at this stage before removing the securing nut (Q/*). Keep the tension of the chain. Pull the chain wheel forwards into full engagement with the vernier, nip up the bolts, put the circlip back in and knock the tabs over. Provided the cam and crank are locked at the correct positions, and you put enough tension on the left side of the chain, it will line up fine.

Michael

 

[esray]

Michael,

Thank you - Brilliant - You have a real talent there - Even I understood both your description and your excellent drawing!

Will post results.

Ray

 

[Keith Coman]

A suggestion/hint to get really solid pressure on the chain's left side [and help free up a hand] is to force the handle of a small screwdriver as a wedge between the chain and the cylinder head rim once you have the cam wheel up on the 'smiley face' and whilst playing with the vernier and cam wheels: you know all's right when the chain and thus the camwheel is locked immovably on the driven

side. [I could not get the locking pin and slot lined up after bolting the cam wheel back to the cam unless the chain's driving side was solid [wedged] during the vernier wheel adjustment process. Simple hand pressure would not do it.]

I fill the chainwheel cavity with paper kitchen towel to minimise the risk of anything accidentally falling down into the lower chain wheel area and sump. For example chain tensioners have been known to fly apart and a moment's inattention can result in a washer or bolt dropping from frozen fingers.​

 

[esray]

Keith,

Thanks for your suggestions. Fingers unlikely to freeze in Cyprus unless I attempt to fix it at the top of the Troodos mountains in winter! Having said that, it might be hot here, but it is certainly not as beautiful as New Zealand!!

Redrover,

I followed your instructions and drawing to the letter and got a complete result - Thank you!

Now, as soon as I get hold of a compression tester I can find out whether I need to be as successful when removing the camshaft and then the head?

ATB to both of you,

Ray

 

[Dave3066]

I had another look at the valve timing on my 2000 as it is still not running quite right after the head gasket change. This is a pic of the flywheel locked in the correct position

and this is the corresponding position of the camshaft sprocket

Now the book says

"On late models the timing hole on the flywheel has been repositioned so that when the flywheel locking peg is inserted the EP mark no longer lines up exactly with the timing pointer. This has been done for assembly purposes and is a design feature to ensure that the timing is correct after timing chains have been fitted and the engine run under power, when all the backlash in the timing mechanism is taken up. It means that the procedure for valve timing during assembly of chains or chainwheels and valve checking after operational running now differ."

The manual also goes on to state that if the camshaft locking key cannot be inserted into the slot in the camshaft sprocket with the EP mark aligned with the pointer and No1 exhaust valve fully open then the camshaft should be turned until the key can be inserted and the valve timing adjusted as has been previously explained....but ensuring that the EP mark aligns with the pointer, not with the flywheel locking pin fitted.

As you can see from the pics above, the relative positions of the EP mark vs pointer and the camshaft locking key vs slot appear to be the same ie they appear to be arriving late to their marks by about the same amount. Therefore should I leave it as is, or lock the flywheel with the pin, irrespective of where the EP is relative to the pointer and adjust the camshaft sprocket to line up the key and slot?

It would seem to me that for correct valve timing, aligning the EP mark with the pointer is more important than ensuring the flywheel locking pin goes in. Can anyone confirm?

Dave

 

[harveyp6]

It would seem to me that for correct valve timing, aligning the EP mark with the pointer is more important than ensuring the flywheel locking pin goes in. Can anyone confirm?

Dave

If that were the case you would never be able to pin the crank and the camshaft at the same time, which totally defeats the object of having the locking mechanism in the first place.

The manual also goes on to state that if the camshaft locking key cannot be inserted into the slot in the camshaft sprocket with the EP mark aligned with the pointer and No1 exhaust valve fully open then the camshaft should be turned until the key can be inserted

There's a contradiction in that as well, because if the No1 exhaust valve is fully open, then the camshaft locking peg must fit, they're on the same shaft. The crank can be out relative to the camshaft, but the camshaft can't be out relative to No1 exhaust valve EP because they are the same part. Moving the camshaft always moves the cam.

Personally, regardless of what the book says, I'd set it up so the pegs fit when it's turned over so having all the slack on the trailing side. Your camshaft is running retarded from what I can see, and what you appear to be seeing too.

The only way to be certain is to put a timing protractor on the crank pulley, and a DTI on a cam follower and then check that against the specs for the valve timing in the book.

 

[Dave3066]

Personally, regardless of what the book says, I'd set it up so the pegs fit when it's turned over so having all the slack on the trailing side.

That's good enough for me Harvey, thanks. It's also exactly what I have done. I just wanted to check the rationale behind it.

Dave

 

[harveyp6]

Personally, regardless of what the book says, I'd set it up so the pegs fit when it's turned over so having all the slack on the trailing side.

That's good enough for me Harvey, thanks. It's also exactly what I have done. I just wanted to check the rationale behind it.

Dave

It will be interesting to see if you see any improvement in the way it runs after doing so.

 

[Keith Coman]

Hi Dave,
Good photos - these help a lot. The flywheel lock is a definitive index regardless of whether the pointer is slightly "off" as regards the EP mark. Your camshaft is out of adjustment, which is where the vernier wheel device comes in.

Set up the cam using the vernier wheel adjustment device as per the instructions provided elsewhere in this forum and you will be rewarded with a camshaft lock that lines up perfectly with slot in the camwheel when the flywheel pin is in. Essential: get the chain as tight as a crab's backside on the driven side.

 

[redrover]

As Harvey says, there's no point in the locking pin if it's not bob on in the right place. I imagine the flywheel will have been drilled after machining, but whether this was done by a multi-spindle drilling machine, or on separate jigs is anyone's guess. I'd imagine a set of guides would have been used as a minimum since it's pretty well critical the holes are in almost exactly the same place (plus or minus a negligible tolerance - ie, less than the slack in the chains), not least because the locking pin would - in all likelihood - have been used when building up the engines.

I have done it another way though. Fraser's new engine is in backwards or upside-down or sideways or something! Whatever's up with it, I couldn't find the hole in the flywheel at any point in its rotation, but as we had the head off anyway we decided set the timing off the piston in the bore. As it's a 2200, the piston stops about 6 foot from the top of the bore (!!!), so we got a steel rule and measured the distance from the piston crown to top of the bore with cylinder 1 at top dead centre, then again with it at bottom dead centre (in other words, the length of stroke plus squish area at the top of the bore). From there, we were able to use the valve event diagram in the workshop manual to work out the EP point by dividing the distance of piston travel (stroke) by the number of degrees of crank rotation, and then adding the 'squish' back on. We marked the bore with a felt marker and then moved the piston from Top and Bottom dead centre, both clockwise and anti-clockwise, measuring each time. When we satisfied that all four movements added up to 360 degrees, and the top-to-bottom and bottom-to-top movements added up to the 180 degrees, we measured again and concluded that the felt line was in the right place. We then marked the pulley where the pointer was, dropped the head back on and set the cam off the pulley wheel at the front.
In theory this method would be just as accurate as using the pin. But I wouldn't want to try it with the head still on. You could stick a screwdriver down and measure from there, but there's a whole load of trigonometry to unravel as the angle of the screwdriver changes in the spark plug hole, corrupting the reading of its linear travel out of the hole. It'd also only really work on a 2200 as the dished and castellated piston crown on the 2000 could give all sorts of barmy readings!

Third method would be to get the piston to TDC and stick an accurate circular protractor on the pulley and rotate the engine the precise number of degrees in the right direction.... Lots to think about anyway!

Michael

 

[esray]

When I try to picture in my minds eye this relationship between the crankshaft and flywheel with it's locked pin and No1 exhaust valve fully closed with the camshaft lock in place, I find the only non-marked variable appears to me to be the accuracy of the position of the cam lobe on No1 EP? We appear to be discussing single degrees of arc when related to the flywheel or camshaft locks but 'eyeball setting' the cam lobe at closed (or rather at 180 degrees from fully open)?

Is this accurate enough, please?

ATB Ray

 

[redrover]

Apols for the 8 month delay, Ray!! I can't imagine you're still waiting on the answer now, but just for clarity, the exhaust cam for cylinder 1 (second cam lobe from front of engine) should be pointing DOWNWARDS when the engine is locked at EP. EP stands for 'exhaust peak' and refers to the exhaust valve on cylinder 1 being at the peak of its opening. There is a notch in the cam flange to lock it there, so you can lock both the cam and the crank independently. I guarantee you won't be able to lock them both first time around - that is the chain stretch you want to compensate for. Lock the crank first, see how far out the cam is, release the chainwheel from the teeth and budge the cam round with a C-spanner (or block of hardwood and a mallet in the notch on the flange), Put the cam locking pin in so everything is definitely right, and tension the left (upper) side of the chain with your finger as you reengage the top chainwheel teeth. Release the crank and cam locks, spin the engine by hand to be sure it's right. Check alignment again after a few clockwise (as you look at the engine) rotations by hand, and then knock the lock tabs over and put the cover back on. Wuh-wuh-wuh-vroooommm!!

 

[pat180269]

I'm planning to do this job on my 2200TC and I've been reading the manual in conjunction with this post. There seems to be some confusion with regard to alignment of the pointer and the EP marker inside the flywheel inspection cover and fitting of the flywheel locking pin. In the manual the following statement is made:-

"On late models the timing hole on the flywheel has been repositioned so that when the flywheel locking peg is inserted the EP mark no longer lines up exactly with the timing pointer. This has been done for assembly purposes and is a design feature to ensure that the timing is correct after timing chains have been fitted and the engine run under power, when all the backlash in the timing mechanism is taken up. It means that the procedure for valve timing during assembly of chains or chainwheels and valve checking after operational running now differ."

As far as I understand it, what the above statement is saying is that the method to be used for checking the valve timing when installing new cam chains differs from the method to be used when checking the valve timing with non new chains.

If you read the procedure for checking the valve timing it says that the pointer should be aligned with the EP marker on the flywheel, no mention is made of locking the flywheel with the pin.
If you read the procedure for changing the cam chains it says the flywheel locking pin should be fitted.
So the two procedures are different.

Given the above I believe I should check the alignment of the slot and peg on the cam with the EP marker and arrow aligned.

 

[redrover]

Hi Pat,

Yes, this is my latest understanding of this issue as well now. I didn't know this at the time i wrote the original post on this thread, but have done a fair bit of investigation and research work since with Ranald White for the prep of his Monte rally car.
When I examined a flywheel from an engine (a 400...G suffix s1 2000 block), I found the hole for the EP pin was at 106 degrees BTDC - I don't know if it differs for other model years, but don't think that matters. The point is - as you rightly point out - by setting the timing by keeping the chains tight with both pins in you will alter the timing - it will set it as 106, which is neither SC nor TC spec! The workshop manual states 104 for TCs and 108 for SCs.

We have to remember that the pin is provided so you can lock the crank while you remove the head to prevent valve collision on reassembly. It's not a timing point. I suppose you're meant to drop the head back on, keep the cam pinned and budge the flywheel round to the right mark for your engine spec as you say. But I'd question whether Rover really did this at Acocks green during the height of production, or whether they just dropped them on with the pins in....

Ranald is having his Monte car rolling roaded in a few weeks. He's having this done at 106 (the pin) to baseline it, and the re-roaded at 104 and 108 to find the difference. I'll post the results when we know.

Cheers
Michaelos

 

[pat180269]

Michael

I've just read the section on locking the crankshaft and the cam and now I'm totally confused.

From my earlier post the manual implies that the valve timing should be checked with the EP marker aligned with the arrow. The camshaft vernier should be adjusted so the camshaft locking pin can be engaged in this position.
So that's adjust so that the camshaft pin can be engaged when the crankshaft EP mark and arrow are aligned.

In the locking the crankshaft and cam section, it says that the crankshaft pin should be engaged and also the camshaft pin; although the EP mark won't align with the arrow.

The two conditions are mutually exclusive.

When I did the head on my car I locked the crank but the cam pin couldn't be engaged. When I came to put the head back on, with the top tensioner backed off the cam pin to my amazement lined up and could be engaged. When I'd finished the job and released the tensioner, I turned the engine over by hand twice and the marks were mis-aligned again.

 

[redrover]

From my earlier post the manual implies that the valve timing should be checked with the EP marker aligned with the arrow. The camshaft vernier should be adjusted so the camshaft locking pin can be engaged in this position.
So that's adjust so that the camshaft pin can be engaged when the crankshaft EP mark and arrow are aligned.

This is the absolute crux of the issue.... it took me a long time to get my head round it too, but I now think the above is plain wrong.

If you look at the pie-chart type diagram for valve event timing, it tells you the point in the crankshaft rotation at which a given cylinder should be exhaust peak. In SCs, that point is 108 degrees. In a TC, that point is 104 degrees.
So we have a constant and a variable. Exhaust Peak is the constant, and (in my eyes) that's read from the camshaft NOT the flywheel pin. Looking the cam puts cyl 1's lobe directly downwards with the valve at the 'peak' of its opening event - so that's the constant.
The variable is the timing point on the flywheel - 108 for SC, 104 for TC. The hole is irrelevant because that's at 106 and has no bearing on the timing diagrams.

So why Rover said pin it at 'EP' and check the cam is beyond me. It's the other way round in my view (although I'll be the first to admit I preached it the other way for a long time!). I think the pin is there purely to keep the crank in 'roughly' the right position while the head is off to prevent valve collision, but the flywheel mark should NOT be called 'EP' as it's misleading. 'LOCK' would do! But as I said earlier, the chances that Acocks Green assembly workers used both pins as a quick was to get the engines together are probably quite high - the pin is at 106 which is bang way between SC and TC.

I say lock the cam, turn the engine backwards (ie anticlockwise as you look at it) and then turn it forwards (so the lower chain stays tight) to either 108 or 104. Then put some tension on the top chain and push the teeth home on the adjuster. Release the cam pin and go.