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timing chain adjuster

Discussion in '365 GT4 2+2/400/412' started by SouthJersey400i, Feb 19, 2014.

  1. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,360
    Romulus, NY (Finger Lakes)
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    Ken Battle
    I have my car into what I believe is a good Ferrari shop to have the timing chain changed and likely the adjuster. He told me to change the adjuster that the whole front engine cover needed to be removed and this requires pulling the motor. Is this true? If adjuster, oring and gasket can be changed with motor in place, please post what steps to take.

    What are chances adjuster does not need to be changed with 65k miles?

    What are typical labor hours to change chain withot changing tensioner?
    Ken
     
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  3. DaveO_48

    DaveO_48 Karting

    Jul 29, 2013
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    David Odland
    #2 DaveO_48, Feb 19, 2014
    Last edited: Feb 19, 2014
    I just looked thru the WS Manual. The bottom pivot of the adjustable tensioner shoe is captured between the block and the front cover. To the extent that the front cover can be removed in the car, the degree of difficulty would increase to the point that removing the engine might be cost effective. The next problem is that you might then get waltzed into the "let's fix this other stuff while it's out" and you end up with a huge, 30K, overhaul bill.
    Did the shop actually run the engine an attempt an adjustment?
    Page B40 and B41. "After 50,000 km, or when the push rod is not long enough for correct tensioning, replace the chain." It doesn't say that the tensioner is shot, it says the chain is. Cam chain replacement might be done in the chassis. A good idea would be to use a bore scope to have a good look at the tensioner surface. It should not wear out before the chain.
    Of course 50,000 km is a lot sooner than 65,000 miles but I don't understand the need for replacing the tensioner unless it had been abused, re: miss adjusted.
    Don't know if this helps but, don't let the cart get ahead of the horse.
     
  4. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
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    Ken Battle
    Dave
    Thanks for reply. I am encouraged that the tensioner pad will be ok, and you confirmed why it cannot be channged easily.

    I was worried about 'scope growth' too.

    I did the adjustments myself since 37000, one adjustment per year after 4-5000 miles. Adjustment ran out last winter.

    I'll let you know result in a week or so.
    Ken
     
  5. alastairhouston

    alastairhouston Formula Junior

    Apr 19, 2009
    575
    Largs Scotland UK
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    Alastair Houston
    Hi Ken
    Can you remind me of the symptoms ie the reason for the idea of chain replacement? I know we touched on this before?

    With the engine in, to be honest I cant quite remember I know the chain needs to be split engine in or out but maybe there is a way of threading a new chain round the guides. More likely than chain stretch is the pads and guide needle bearings etc.

    Easy to check chain tension is take the front covers off.

    If you are rich (and it wont do any harm!) its a good idea to take the engine out but if you want to do things properly it will be very expensive either in time and money if your poor or money only if your rich!

    Engine out costs for disassembly/reassembly and front cover work materials etc expect $8000/$12000
    Proper full engine rebuild $25000/$30000
    Regards
    Alastair
     
  6. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
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    Ken Battle
    Alastair
    I was out of travel on adjuster.

    Only way I can afford the car is to 90% of work myself. This is first job outside my garage in 6 years
    Kendall
     
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  8. daytonaman

    daytonaman Formula Junior

    May 1, 2007
    647
    Australia
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    howard pigdon
    I've not seen it, but have heard of someone taking out joining link,attaching new chain and slowly winding the new one in till the old one is completely out. Then insert the joining link in the new chain.
     
  9. Ak Jim

    Ak Jim F1 Veteran
    Rossa Subscribed Owner

    Dec 23, 2007
    5,527
    North Pole AK
    Why did you adjust after 4000-5000 miles? Was it getting noisy, or does the book recommend adjusting it that often?
     
  10. alastairhouston

    alastairhouston Formula Junior

    Apr 19, 2009
    575
    Largs Scotland UK
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    Alastair Houston
    Ahh with you Ken, ok financial damage limitation heres my thoughts.

    Is the chain rattling?
    with engine in you could try back up the adjuster all the way, split the chain and drop out a link then reassemble you will get the pins and info needed from Reynold who make the chain. Or replace the chain with one less link (if it is the same lenghth as the old chain) I think but not 100% you may be able to thread the new chain around. I have replaced chain with engine out so now I think of it cant see any difference in just pull the new chain round with the old one loosely.
    Both these options will need the camshaft timing reset.

    Both these options don't address the more likely cause of out of adjustment which could include needle bearings on the pulleys, main bearing and pads including adjuster pad all inside the front cover ime afraid.
    Regards
    Alastair
     
  11. wrxmike

    wrxmike Moderator
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    Mar 20, 2004
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    #9 wrxmike, Feb 20, 2014
    Last edited by a moderator: Sep 7, 2017
    I think it might be possible to replace the top chain engine in, although I've not done it.
    *If* I had to replace the chain, I'd try to do it with the engine in first, and if that didnt work, I'd remove the engine. My view is that you'd be no worse off for trying it first.

    But I don't think it's possible to "roll" it in, with the cams in place the chance of piston / valve contact is to great.

    I'd remove all the cams (so all the valves are closed), them I'd to split old the chain and wiggle it out, with the new chain attached to one end of the old chain, and turn the crank to help get the chain past the gap between 4 & 17 in the attached diagram and once the chain was through, re time the engine ( ie set to TDC, line up the cams etc.
    Big job, PITA, but less work than pulling the motor and removing the timing cover....

    M
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  13. alastairhouston

    alastairhouston Formula Junior

    Apr 19, 2009
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    Alastair Houston
    Spot on Mike
    also I think you can avoid removing cams by extracting the two pins 10 and 11 then the two cam end pulleys will rotate freely.
    Once the chain is in and tensioned correctly engine will need to be turned over to 'settle' the chain then recheck cam timing.
    Regards
    Alastair
     
  14. alastairhouston

    alastairhouston Formula Junior

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    Alastair Houston
    #11 alastairhouston, Feb 20, 2014
    Last edited by a moderator: Sep 7, 2017
  15. wrxmike

    wrxmike Moderator
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    Hi Alistair
    The reason I recommend removing the cams is so that all the valves are closed, which allows you to rotate the crank if neceesary to pull the chain past the bottom pulley. Otherwise the concern is that if you rotate the crank with the cams in place, the pistons will hit the valves.
    What you describe is necessary once the new chain is installed to fine tune the cam timing.
    BTW your engine looks clean, must be pleasure to work on outside the car.

    <
     
  16. alastairhouston

    alastairhouston Formula Junior

    Apr 19, 2009
    575
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    Mike you are right, to get the chain past the bottom pulley you need to turn the crank to help it through and indeed removing the cams would be necessary or you could get away with loosening the caps for this procedure.

    A side note with the mileage on this car it will need the valve clearances adjusted and new shims which are far easier to replace with the cams off, although there is a special shim removal tool its still far easier to remove the cam.

    Will try to remember the business card trick for later chat which keeps the cam from rotating when you use it to stop unwanted movement when setting up the timing.
    Regards
    Alastair
     
  17. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
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    Part of the estimate on my job is to check valve lash.

    Somehow removing a link from chain sounds like timing will be off and get further off with each revolution???? I have to think about that more with the PDF posted in hand.

    I have given shop go ahead to start the job after working out payment terms.

    I'll update all in a week or so.
    Ken
     
  18. DaveO_48

    DaveO_48 Karting

    Jul 29, 2013
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    Removing a link would take up slack in the chain. It could still be timed correctly. It does not correct the real, and possibly catastrophic problem. As chains stretch they change the "pitch" or link spacing between rollers.On a V-12, the problem would be total chain failure from being run around sprockets that are hardened and not the pitch of the stretched chain. This is the reason link removal isn't done in valve timing on an interference engine.
     
  19. wrxmike

    wrxmike Moderator
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    1: If the chain has stretched to the point where you need to pull a link to get back in to the range of the tension adjuster, the chain is well and truly worn and needs to be replaced.

    2: You can still time the engine correctly after having removed a link, although you would need to change the setting of each cam sprocket vernier so that everything lines up

    3: The effect of a stretched chain ( and cams timing being out ) has a massive performance effect on these engines, in particular 412's. Here's why.

    I assembled an engine with the timing out by 1 tooth of both cam gears on one bank of the engine . The engine ran OK (valves wont hit with it out 1 notch). Compression test on that bank was 130 psi and 175 on the other "good" bank I then set the cam timing back to the correct setting, the compression was 175 psi on both sides. If the cam timing is out, the valve/piston relationship is wrong, and the engine wont make full compression. ( I wonder how many low compression engines have been rebuilt as a result of a looooong chain )

    Also, on the 412, the distributor cap is fixed to the engine and cannot be rotated and the ignition rotor is bolted to the end of the cam. If everything is within spec, it all lines up and the spark can travel as it should.

    But if the cam is not timed propely due to a stretched chain, the ignition rotor is in in a less than optimal position in relation to the cap, which results in a weaker spark and less than optimal timing.

    M
     
  20. rovexienus

    rovexienus Formula Junior
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    Jun 10, 2010
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    Jean-Michel Savary
    My teen cents on this subject: the garage where my cars are maintained has recent experience of remaking the entire distribution of one 365 GT4 2+2 and one 400i. Engine out on both occasions. On comparing the parts old and new, they saw that the old chains had only marginally stretched (with respect to the new ones), but that the gears had sustained visible damage, including partially broken gear teeth.
     
  21. alastairhouston

    alastairhouston Formula Junior

    Apr 19, 2009
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    #18 alastairhouston, Feb 21, 2014
    Last edited by a moderator: Sep 7, 2017
    Good points
    It is unlikely that the chain will have stretched that much, more likely worn pully needle bearings pads etc as mentioned in my last post. link out wont affect timing once corrected.
    This is to avoid engine out.

    It will probably be necessary to pull the engine if you want to put a new chain in full length because likelihood of worn pads etc accessible only with front cover off. Still it would be worth trying engine in.

    Mike absolutely on the cam timing there must be quite a few cars running lack of power due to incorrect cam timing a few mm off the marks is acceptable but no more I set mine to bang on right in the middle of the marks after proper settling of the chain. Its reasonably easy procedure to adjust.

    See pics note greased cam for the chain settling and pic of a chain with 30 000 miles on and a brand new chain with no miles on not one mm of stretch amazingly.
    Regards
    Alastair
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  22. 180 Out

    180 Out Formula Junior

    Jan 4, 2012
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    Bill Henley
    Very interesting information in this thread. Sorry that Ken has to spend thousands to bring these things to light for the rest of us. The 45 psi difference between a retarded cam and a straight up cam that Michael recorded is startling. This indicates that the intake valves were not closing until the pistons had traveled upwards many centimeters on their compression strokes.

    I am puzzled about needle bearings on the pulleys. The cam gears or pulleys -- or more precisely imho sprockets -- are fixed solidly to the ends of the camshafts, and likewise the crankshaft gear. The camshafts ride in plane bearings, don't they? Or do they use a needle bearing? The main (crankshaft) bearings: are these plane bearings, or rollers or needles?
     
  23. DaveO_48

    DaveO_48 Karting

    Jul 29, 2013
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    The rotating parts, cams and crank, are on surface bearings no rollers or needles. Only the idler sprockets use needles. As to the chipped teeth mentioned, it is caused by a chain that does not want to stay in the sprockets because the links are too long. This causes sprocket "topping" and, when the sprockets are hardened, chipped teeth.
    Wear from stretched chain can be seen in dirt bikes that have been run past the replacement point. There the sprocket isn't as hard and the teeth bend. You may have seen this, usually on a child's or younger riders bike where maintenance isn't done regularly.
    This is why when the chain gets replaced before other damage occurs, the rest of the parts will still be useable.
     
  24. Ashman

    Ashman Two Time F1 World Champ
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    Sep 5, 2002
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    The information about timing chains in this one thread is greater than all of the information that I have seen on FerrariChat in the past 12 years! In fact, it is more informative than the workshop manual dealing with the topic.

    Well done everyone!
     
  25. alastairhouston

    alastairhouston Formula Junior

    Apr 19, 2009
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    Alastair Houston
    #22 alastairhouston, Feb 21, 2014
    Last edited by a moderator: Sep 7, 2017
    Ahh good stuff John
    Bill, Dave excellent indeed. Yep I reckon 'sprocket' is the chosen word Dave is correct idlers have the needle bearings.

    Also see pics the first photo shows the cover, the main timing gear driven shaft from the crank with the bearing attached is a roller bearing and it, in my instance showed reasonable wear and need for replacement (@30 000 miles). Next photo shows the engine side where the bearing slots into.

    Regards
    Alastair
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  26. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
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    Romulus, NY (Finger Lakes)
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    Ken Battle
    I picked up one point in the last day of this thread. I will need to recheck the ignition timing when I get car back although I will check to see if shop does it. I kind of like laying under car with the motor running with a timing light in my hand. Best part is when wife is revving it to 5000 to check the advance. I will only need to do the idle check since distributor was rebuilt last fall.
    Ken
     
  27. DaveO_48

    DaveO_48 Karting

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    #24 DaveO_48, Feb 21, 2014
    Last edited: Feb 21, 2014
    From looking at the upper photo, in your post, it appears there was an issue with the cam chain hitting the driven gear. Note the shinny lines on the face of the gear that line up with the link pins. Could it be that some of the stretch @ 30,000 miles was due to this interference?
     
  28. blkprlz

    blkprlz Formula 3

    Mar 24, 2007
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    #25 blkprlz, Feb 21, 2014
    Last edited: Feb 21, 2014
    I made note of Brian Crall's remarks about changing out timing chains in our cars:

    "The front cover 'will not' come off in the car.

    &#8232;&#8232;The front cover is not removed to do a timing chain. &#8232;&#8232;Hook the new chain to the old one and roll it in.

    Keep the chain engaged on the cams so they stay in time. The other choice is to pull the cams.

    The chain cannot simply just be fed through and pulled up the other side. I've done it with and without the cams in the car."

    Then someone asked if you can loosen the cam bearing caps so the valves are out of the way & Brian's response was "By the time you do that might as well just pull the cams."
     

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