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Valve timing fine adjustment

Discussion in 'Rover P6 Engine 4 cylinder' started by redrover, Nov 28, 2011.

  1. redrover

    redrover Active Member

    Due to my engine rebuild probably being shelved until the forseeable, I'm faffing around with other things to get the engine as good as possible without major surgery.

    I want to set the valve timing up properly (as I am convinced it's out), and take up the slack from stretched chains.
    I heard from a club member that moving the vernier adjuster by 4 teeth in one direction or the other gives greater power or economy in the 4-pot. Is this true?
    If so, what direction for more POWER :twisted: !!!

    I'm assuming it should be advanced? So the cam should reach exhaust peak before the EP mark lines up??? :|

    Michael
     
  2. restojon

    restojon New Member

    I wasn't aware you had a vernier adjustment for valve timing, can someone clarify this for us please? :?:
     
  3. harveyp6

    harveyp6 Well-Known Member

    The camshaft sprocket has the vernier adjustment in it.
     
  4. restojon

    restojon New Member

    I'll be looking into this, it may be the answer to some of the problems I've been having with the timing on my car. Can this adjustment slip over time by any chance?
     
  5. harveyp6

    harveyp6 Well-Known Member

    I can't see how it could slip, but it could have been set incorrectly initially. Easiest way to find out is to peg the crank and camshaft and see what happens. If you can't get the camshaft peg in with the crank pegged then it's out.
     
  6. restojon

    restojon New Member

    It's out then :cry:
    I don't have a manual to hand right now, I've had a flood at home and everything is in storage. Is there a section in any manual describing a procedure or is it a case from working from the cam timing figures stated and sticking a degree disc to the engine somewhere and working it out?
    Thanks.
     
  7. harveyp6

    harveyp6 Well-Known Member

    It will be in the book, but it's just a case of pegging the crank, then if the camshaft peg won't fit, back off the top chain tensioner, then remove the camshaft gear, peg the camshaft, and then alter the vernier until the cam gear fits back on with all of the slack on the trailing side of the cam gear. Then turn over a couple of times by hand to check.
     
  8. GrimV8

    GrimV8 New Member

    I did one on a customers car that's been out for decades. Performs well, best he's known it but runs on now :roll: coked up I'm guessing. I've been ragging it round at his request (in a sedate Roveresque way) but no improvement as yet.

    I'll talk you through it Saturday Jon if you want confusing :mrgreen:
     
  9. restojon

    restojon New Member

    I'll look into this on the weekend then, it's definitely lost some performance and it has an occasional tendency to run on. I'll see you on the weekend Grim, I may even bring spanners.
     
  10. GrimV8

    GrimV8 New Member

    I don't work weekends :mrgreen:
     
  11. redrover

    redrover Active Member

    I've dug out the workshop manual and read the section on checking/resetting the timing.

    I'm off today, so I'll pop out this morning and have a good fiddle. Some pics may follow....
     
  12. redrover

    redrover Active Member

    Fiddle complete, and pleased to say the results are noticeable.

    The camshaft was about 8 teeth of the vernier out, and as to be expected was retarded due to stretch in the chains. Lined everything back up properly and all was a go (must say, clever as the whole detachable chain wheel business is, it's not exactly easy to move the teeth around - it's like doing dentistry!)

    Got the upper tensioner out as well as the chain's been ringing away like a bellset for a while. I was expecting it to be worn down to the metal, but it must have been replaced in the last 10,000 miles as it was basically new. A bit of crud in the cylinder was impairing it's movement (the old oil strainer was split!). All seems a lot quieter now.

    Acceleration seems better (but I am still not 100% used to the new carbs, so am unsure of how much difference has been made). However, the difference to the idle is astonishing. It idles smoothly at 600rpm and is as steady as a liner! I could never get anything smooth below 900 before, and even then a hot idle was lumpy.

    A day well spent for me and redrover! :D
     
  13. mf.smith

    mf.smith New Member

    Would like to see photos of that, for future reference, if you've taken any....
     
  14. restojon

    restojon New Member

    Very interesting Redrover, the symptoms you describe of the lumpy idle below 900 echo's my own problems (although my car is more unhappy below 850). I shall look into this on the weekend in the light as I said earlier and see what the score is in there. If I get chance I may get pics too especially if I can catch Grim working on a weekend :wink:
    Thanks for raising this point Redrover, you may have preserved my already struggling level of sanity where my cars are concerned :lol:
    I've had a feeling that the timing was late as you can hear the exhaust note up by the headers, almost like a gentle pinking but not quite and no way to dial it out, looking forward to the weekend now.
     
  15. v8guy

    v8guy Active Member

    Well done Micheal its great when you can sort out a problem with out it emptying your wallet :D

    Is this weekend tickets only then :?: :lol:
     
  16. redrover

    redrover Active Member

    Glad to hear I might have given you something to look forward to! Yes, I had exactly the symptoms you now describe, coupled to quite a splashy exhaust note (but then I do have a big bore, so I suppose that is exaggerated), so it may well be that we have similar issues - quite likely all things considered.

    It was a bit dark, so only one or two shots are any good, but I've snapped some pages from the workshop manual to help (sorry about the quality!). Basically what I did it was....

    I whizzed the rocker cover off and rotated the engine by hand until the exhaust valve of cylinder 1 was open (ie, 2nd valve in from the radiator was depressed by the cam) - having the plugs out really helps make this easier and more precise. I then opened the little inspection cover on the flywheel housing (beneath the washer bottle) and looked for the |EP| mark to come in line with the small pointer.
    [​IMG]
    There is a pin bolted onto the outside of the flywheel housing next to the engine (above right diagram). Undo the 7/16 AF bolt, turn the pin around and slide it in through the hole until it goes through the flywheel (a lot of jiggling required here!) and locks it in position.

    Then take a look at the upper chain wheel. This is what mine looked like:
    [​IMG]
    The slot on the camshaft flange should line up with the steel 'L'-shaped pin that is bolted down with the strap. On reflection, mine was probably only 5 teeth out, but even this 'small' change has made a fairly dramatic difference.

    [​IMG]
    Next, I knocked off the lock-tabs on the two bolts holding the chain wheel to the camshaft and took the left hand one out (they are positioned at about 10 and 4 o'clock when in the EP position - not the position shown in the pic!). I backed the right one off until it was nearly out but still gripping the thread. I then pulled the whole chain wheel forwards until the central thread poked through the 'smile'-shaped slot in the front mounting bracket and put a 9/16 AF nut on it. I used one of the nuts on the steering idler bracket for this (just needed to remember to put it back!). I then took the right hand bolt out of the chain wheel, and also extracted a simple wire circlip (visible at 9 o'clock on this wheel in this pic).

    The camshaft was now free. I rotated it by nudging it round with a hammer and a thin piece of wood placed in the slot on the flange until it lined up with the L-shaped pin. Once aligned, I undid the clamp (first picture) that holds the 'L'-shaped pin down and rotated it so the right-angled side was pointing skywards, slid it forward so that it engaged the slot in the camshaft flange and bolted the clamp back on (see left pic in first diagram).
    [​IMG]
    Then using a bit of force, I eased the outer ring of the chain wheel off the inner circle wheel. The tiny teeth are visible at this stage, and it's just a matter of pushing the outer wheel off the back. Once free, I kept tight hold of it so as not to slacken the chains and cause the tensioner to fall off inside. If you push it away from you, it actually sits quite neatly over the end of the camshaft flange, allowing you to leave it safely there while you faff with the central wheel bit.
    For the next bit, I found it easier to take the 9/16 AF securing bolt off the smiley-face bit and handle the inner toothed wheel separately. I put the long bolts back through it (with the locking tab), lined these up with the bolt holes in the camshaft, but only screwed them in just far enough to grip, whilst still allowing the chain wheel to move independently (ie, teeth not yet meshed). The trick then is to put as much inwards force as you can on the left side (as you are looking at it) of the chain to pull the right side (the driven side) really tight. When it's taut, simply pushing the inner wheel home until its teeth mesh with the chain wheel, whizz up the bolts and..... refitting is the reverse of removal, as they say!
    If the teeth won't line up, spin the wheel through 180 degrees, and it will fit that way. It has an odd number of teeth, which is over-engineering to the nth degree!

    Oh, and don't forget to take the L-shaped locking pin out before you put the rocker cover back on! D'oh!

    That's how I did it anyway. Took me about 2 hours, as I took the chain tensioner out for inspection and checked the valve clearances as well.

    Michael
     
  17. darth sidious

    darth sidious New Member

    Did the pin go in with the EP lining up with the pointer? I recall on the transplanted 2000TC unit we put in our old 2000Auto, the pin wouldn't go in when EP lined up with the pointer, but would when the EP mark was obviously out.

    In fact, didn't someone on this forum state some months back they'd heard this "pin won't go in at EP" issue was intentional for some reason?

    I :evil: HATE :evil: when timing/datum marks are wrong! What's the point of having them if they're wrong?! It's like baking a cake to perfection, then just slapping on the icing any-old-how; totally ruins it!!!!!!! :evil: :(

    Rant over, I promise! :D
     
  18. restojon

    restojon New Member

    I have the splashy exhaust note too, great post you've made there with all the pics. I shall put your experiences to good use on the weekend and report back. Thanks for taking the time to put that up I'm sure quite a few owners will find this very informative and useful especially as winter fettling time is now upon us. I've had a small number of other issues on my car which I've been chasing round for some time now but have not been able to quite crack as no amount of fettling or dialling in/out would cure them and throughout this I've been convinced that the cam timing is and probably always has been slightly out. I'm crossing the fingers that this is the key to all of it and I can get my old trooper running nice and sweet. :D
     
  19. Willy Eckerslyke

    Willy Eckerslyke Well-Known Member

    The manual (official one) says that later engines were set like this to allow for backlash in the chains. It also says you can identify these engines from the shape of part of the cam wheel.
     
  20. redrover

    redrover Active Member

    I must admit I didn't come across that info in the manual, but the pin slid in easily at the EP mark anyway. My car was registered 1972, but given some of the trim, I suspect it was probably built during 1971 model year production. That may help/hinder others if their cars are earlier/later.

    Michael
     

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