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Timing adjustment in MJD

Discussion in 'Engine Compartment' started by Sat-Chit-ananda, Oct 28, 2013.

  1. My experience with timing adjustment with my 76HP Punto.
    As several of you know , i got my timing chain/sprocket replaced couple of months back. Car was sluggish to drive for some time.
    I went back to Harish again, CAM timing angle was adjusted a bit and car started flying.
    I had to go back again for adjustment last Saturday now it is perfect and how i wanted it to be.Well you may be surprised by this time why i had visit Harish's SC thrice to get Timing adjusted?
    Well it's all part of learning, it is little complex to understand at first sight but never mind you will get it with little bit of personal experience.
    First time after the chain adjustment car was feeling sluggish , this was due to timing being in slightly retarded tune.
    When adding fuel and boost(Remap) in the quest for better performance, a key component, timing, is often overlooked. Timing mechanically injected diesels all of which use rotary injection pump) is simple in practice, but understanding the why and where to time is what this article is all about.
    Most diesels come off the line tuned for moderate power and little or no smoke, and as miles are added and power drops off, the general wisdom has been to advance the pump to reclaim some of those lost horses. We'll look deeper into the idea of diesel timing, and its practical application on the project MJD engine.

    Diesel Timing: an overview
    Conservative timing results in low nitrogen oxides (NOx) emissions. For our MJD project engine, that resulted in the timing marks perfectly aligned which was top dead center (TDC) or middle distance in the cylinder for a piston. While lower timing figures like these are best for NOx levels, as does carbon monoxide; hydrocarbon levels decrease. In addition, centered timing decreases cylinder pressure and reduces peak flame temperature since the fuel charge is injected once the piston has past TDC and is already on its way back down the cylinder in the power stroke. This is why it is more difficult to get a complete burn, and it is this hot, unspent exhaust gas that gets past the valves and decreases turbo lag. You will see better low end performance

    On the other hand, advancing the timing results in increased cylinder pressures and higher peak flame temperatures which leads to a more complete burn of the fuel injected. This is demonstrated by a drop in exhaust gas temperatures, and increased turbo lag. The effect on emissions is significant. The NOx level increases dramatically past just a couple of degrees of advance, while hydrocarbons increase and carbon monoxide decreases. You will see better mid and top end performance.


    Well it's all part of learning, it is little complex to understand at fist sight but never mind you will get it with little bit of personal experience.

    First time after the chain adjustment car was feeling sluggish , this was due to timing being in slightly retarded tune.
    Below pic shows camshaft pulley
    IMG_20131019_115047.jpg
    Here is the crankshaft pulley
    IMG_20131019_123322.jpg

    - - - Merged Post - - -

    Oil flange needs to be removed to free up the timing chain for adjustment.
    IMG_20131026_120249.jpg


    IMG_20131026_120257.jpg

    - - - Merged Post - - -

    Two Camshafts and crankshaft needs to be locked before embarking on this exercise.
    Here is how it is done .Harish locking the crankshaft.
    IMG_20131026_112319.jpg

    Cam locking tool
    IMG_20131026_115822.jpg

    - - - Merged Post - - -

    Oil seal replaced with new one as we had opened the flange several times.


    - - - Merged Post - - -

    Here is crankshaft being rotated to get to locking position
    IMG_20131026_112343.jpg

    - - - Merged Post - - -

    Harish checking the position of cam before locking it.
    IMG_20131026_112307.jpg

    - - - Merged Post - - -

    Remember there are two camshafts in MJD, one where Harish is looking at other one is right below the CRDI common Rail pipe
    Last edited by a moderator: Oct 28, 2013
    3 people like this.
  2. Once Crank and Cam's are locked and flange is removed turning the Cam Pulley anti clock wise will retard the timing, where is low end torque will improve but middle and high will be sluggish.
    Retarded timing Cons:
    - Poor performance
    - Poor FE
    - More smoke but may not be that high in Multijet engine
    - Harder cold starts
    -Lower cylinder pressure
    - Higher Exhaust gas temperatures,which can affect valves and turbo.

    IMG_20131019_121435.jpg

    Turing clockwise will set the advanced timing
    What happens when the timing is set to advanced
    - Very good performance in mid and high Rev range
    - Good FE
    - Slightly more Diesel clatter at idling
    - Higher cylinder pressure
    - Lower Exhaust gas temperatures but, high Nxo2 emissions.

    Setting it exactly in center between advanced and retard is the right timing for MJD.Play between two points after locking cam is just about 2-3 mm only.



    I have tried my best to capture most of the steps, please let me know if you have any questions.



    Here is summary of the Pro's and cons,Timing chain will get expended over period of time might change the timing a bit.
    better to set the timing slightly advanced but well below max advance setting so that when the chain sags timing will still not retarded.
    Advanced timing Pros:
    - More power, particularly at high revs
    - Improved MPGs
    - Easier cold starts
    - Less smoke
    - Lower EGTs

    Advanced timing Cons:
    - Higher cylinder pressures
    - Higher NOx emissions

    Retarded timing Pros:
    - Lower NOx emissions
    - Lower cylinder pressures

    Retarded timing Cons:
    - Poor performance
    - Poor MPGs
    - More smoke (tons more with performance mods)
    - Harder cold starts
    - Higher EGTs

    Note that the relationship between timing and EGTs in a diesel is opposite that of a Petrol engine.
    Last edited by a moderator: Oct 28, 2013
    HareeshCR, SoumenPaul, johnny and 3 others like this.
  3. PS and Alternator belts needs to be removed to as prerequisite to this activity.
  4. One thing I forgot to mention!! once you have got the timing you wanted put the oil flanger and tighten the bolts so that timing stays as you want it.This is very important it just slipped out of my mind while composing.
    Please click like, if you appreciate the information:)
    Last edited: Oct 28, 2013
    HareeshCR, @Romeo, ghodlur and 3 others like this.
  5. Yesterday for the first time after timing chain replacement i got 15.5 kmpl while returning from office which includes couple of 3 minutes traffic stops, i used to get ~11-12.5 earlier :).
  6. During my recent trip of 1800 kms,i got 23.3 kmpl upto hubli and 21.5 kmpl upto badami.
    I was doing speeds between 90-120 kmph.over all FE was 18.6 kmpl.
    Timing adjustment has positive effect on my pocket now.
  7. ghodlur

    ghodlur Esperto

    Messages:
    2,317
    Thane
    @Sat,

    Thanks a ton for the detailed posts with pics.

    Two questions:
    1) Is there a possibility that the timing chain adjustment to be shifted, I mean to be changed over the period of running?
    2) Was this done at Fiat workshop or FNG? I hope you got the timing chain replaced from FASS?
  8. 1) Chain will sag a bit which will alter the timing by few degrees, usually it tends to go to retard if unchanged for more than it's usable life.Tjat will be any where between 60 to 100k kms.
    2)I got it replaced at Pride cars not FASS,i doubt FASS can do better job than Harish.
    Last edited: Nov 11, 2013
  9. gurjinder

    gurjinder Staff Member Janitor

    Messages:
    3,989
    Punjab
    Let me give you an analogy which shall demonstrate the utter falsity of the above statement:

    Does a loose chain on the motorcycle cause the sprocket to jump a few teeth?? Nope. So how in God's name can the timing get altered? You're just imagining things.

    I remember reading a post from you telling another member to verify facts before posting. I shall have to say the same to you today.

    Cheers.
  10. My time to wear a flame suit.okay never backed down in the face of adversities.
    First of all i never said it will skip few teeths of the sprocket.

    Timing is precision thing can not comapre with motor cycle chain, we are talking about degrees here not even a millimeter.
    Being respectively to your role in the forum, i do not agree with comparison.
    What i did not mention is the play in the cam is just about 2-4 mm!!! Yes if you set the play to 2 mm assuming max play is 4 mm it is set to neither advanced or retard.
    A sag in the chain can introduce increase in the length of the chain.
    If you agree to my above statement, increase in lenght of the chain will create a mismatch between two rotating pulleys enongh to create a few degees of delay in cam as it being the driven pully.

    Althogh not entirely related to this there is line talks about changenin the timing due to elongated chain VVT & Timing Chain Replacement

    It is little disappointing to see poor choice of words used to question my post.
    Last edited: Nov 11, 2013

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