!! 328-Screwed up my rear bank cam timing, need expert advice! | FerrariChat
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!! 328-Screwed up my rear bank cam timing, need expert advice!

Discussion in 'Technical Q&A' started by greg328, May 19, 2012.

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  1. greg328

    greg328 F1 Rookie

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    #1 greg328, May 19, 2012
    308/328 experts:
    Looking for some good advice, and I may need to hire an expert to accompany on this issue. Car in in my garage, on 4 lifts, Houston, TX.

    My rear-bank exhaust cam moved clockwise three teeth. Oops.

    I'm in the middle of my 328 timing belt and tensioner service. I've removed the rear belt cover, locked the cam gears, removed the old belt after making marks (on both belts-matching to new) and pulleys.

    The front bank is still untouched and perfectly timed.

    I installed my new Hill tensioner bearing, pushed all the way in and locked down so I could fit the new belt in place. Belt wouldn't go, no way. So, I called Verell, he said to turn the crank pulley just a little bit to create more tension on the long side of the belt, to allow more slack on the bearing side. In doing this the cam gears moved a little bit, and I noticed that the intake cam was off 1 tooth in relation to the belt mark. So, foolishly, I removed the cam lock (c-clamp) and tried to move the exhaust cam a little bit to hopefully get the belt to line up with the other marks (intake and drive pulley marks). Well, the exhaust cam gear (the rearmost cam gear on the car) clicked clockwise about 3 teeth and stopped. It was felt as though it was under spring pressure, and then came to an abrupt halt. Don't know if it caused contact between valve(s) and piston(s) or not. I don't fully-understand how the cam timing works. Maybe the cam lobes stopped the gear.

    Here's the bad news--I didn't mark TDC cylinder 1. I know I should have, but I clamped and went on my 77 GTB a few years ago and all ended well. I feel pretty stupid. :-(

    So, now, the rear bank is off--a little bit. I tried to rotate the cam gear back counterclockwise by hand to return to the mark (I marked both cam gears in relation to each other, to ensure I could get back there.), but it won't budge counterclockwise.

    I guess the first stupid question is: can I continue to rotate the exhaust cam clockwise 1 full revolution and try to get it back to where it was? 1) would that cause valve/piston contact and, 2) does indeed one rotation of a cam gear return everything to the same position?

    Second question--If I can't clockwise rotate back to where it was, will I need to remove the rear camshaft cover, pull the cams out and re-align them to TDC, after I turn the engine to TDC? (If first question's answer is no, then obviously I need to pull the cams to be able to spin the engine freely, correct?)
    Since the front bank is untouched and intact, are those cams OK to leave alone?

    I've never removed a Ferrari cam cover and dealt with cams, so this one's got my attention. If indeed the rear cam cover needs to come off, I'd appreciate a list of seals and gaskets I'll need on hand. I searched the site for a 308/328 camshaft R&R procedure, couldn't find one, I'd appreciate a link if possible.

    Sorry for the novel-length post.
    Any advice offered would be GREATLY appreciated!

    Greg Giacona
    Houston, TX
    cell (two-eight-one)-74eight-64hundred
    1987 328 GTB
     
  2. TdF

    TdF Karting

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    #2 TdF, May 19, 2012
    Do you have ice? Some gin and tonic?
    Good, - mix and sip. Relax. You're about to be led
    through your valley of darkness.
     
  3. greg328

    greg328 F1 Rookie

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    #3 greg328, May 19, 2012
    Oh great.

    Is there a procedure on here somewhere to R and R the cam covers and cams, and how to set timing?

    Greg
     
  4. Matto

    Matto Formula 3

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    #4 Matto, May 19, 2012
    Are you at TDC?

    You should be able to turn any cam carefully in either direction with a good ratchet. The only thing that holds it/drives it is the belt. I'm hoping that you made some good marks on your pulleys and belt(s) before taking it all apart?
     
  5. Glassman

    Glassman F1 World Champ
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    #5 Glassman, May 19, 2012
    If you don't have each cam marked clearly where it was at the start.....what are you going to turn it back to??? Just guess about 3 teeth?
     
  6. greg328

    greg328 F1 Rookie

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    #6 greg328, May 19, 2012
    Guys, I appreciate your posts, but please re-read my original post. I do not have the engine locked at TDC 1. My bad, I feel bad about it.

    I do have LOTS of marks, on both cam gears, lower drive pulley and belt. I know exactly how each cam should orient--I even have the two cam gears marked in relation across from each other, with a level line. They just got a little off in my effort to gain some slack by turning the crank balancer bolt.

    So, since I'm not at TDC 1, this means if I turn that exhaust cam further clockwise it'll force some valves into contact with pistons? It may be already touching, because of the strong detent I felt when the cam gear moved a bit clockwise (about 3 belt teeth-worth). It stopped securely, so I wonder if valve spring pressure stopped it, or a valve touched a piston. Again, very little impact occurred, so I doubt any damage has happened.

    It would be GREAT if I could simply continue to rotate that exhaust cam clockwise around to the original position, but I don't see how I can, with the engine not at TDC 1. ??

    It's my hope against hope that I won't have to remove the rear cam cover and cams to re-time, but if I have to, I'm willing. I need a procedure though.

    TIA,
    Greg
     
  7. Matto

    Matto Formula 3

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    #7 Matto, May 19, 2012
    It should have only popped over the short distance that you describe. If the crankshaft hasn't moved at all, you should be able to rotate it back from where it landed, without a full revolution of the cam. It may feel really tight due to valve spring tension, but it should turn. You should be able to carefully roll it back to your correct pulley/belt marks. When I did my belt service, I didn't lock the cams. When they popped over, I rolled them back.
     
  8. greg328

    greg328 F1 Rookie

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    #8 greg328, May 19, 2012
    Wow, that would be great news! I couldn't manage to turn it with hand pressure, so you recommend putting a socket on the cam gear bolt, and just try and rotate it back CCW that little bit?

    <sweats profusely>

    :)

    Greg
     
  9. Matto

    Matto Formula 3

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    #9 Matto, May 19, 2012
    Last edited: May 19, 2012
    On sure, no worries, but I do understand your anxiety :) The valve springs are substantial (and several). You need a good wrench on the bolt to be able to turn the cam (a bit of leverage). If the belt is off, the cam is free to rotate. Just carefully turn it back to where it started and to your marks. It should only have popped a short distance before the next lobe stopped it. If you took the time to do a good job on your marks, trust them. Consider that the cams always want to roll over and release spring tension, that means retraction of the valves, not extension. Simply rolling it back won't result in a collision in the cylinder. A full rotation of the cam isn't necessary.

    With the crank not having moved from its marks, you won't have any bent valves.

    A very 308-savvy friend wisely told me once "Don't fear the cams" ;)
     
  10. greg328

    greg328 F1 Rookie

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    #10 greg328, May 19, 2012
    This is wonderful news. I so appreciate the info, it's truly peace of mind for me.

    Once I get everything lined up again I'm going to loosen the tensioner mount plate to gain a bit of slack on the belt.
     
  11. Glassman

    Glassman F1 World Champ
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    #11 Glassman, May 20, 2012
    Sorry....I thought you said that you did not mark the cam pully positions. You are in OK shape then. But I guess now we know why everyone says to take the engine to TDC before starting. At least then you know exactly where everything is positioned.
     
  12. greg328

    greg328 F1 Rookie

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    #12 greg328, May 20, 2012
    So, to re-state the perhaps obvious, as long as i haven't moved the crank around, it's safe to rotate the cam back ccw just the little bit (about an inch-3 teeth) to the original position, TDC 1 or not? seems to make sense as I'm only returning it to where it was. I guess my main concern was that i couldn't return it by hand, even though it turned easily by hand clockwise. this is simply the spring pressure i assume. the way it stopped so firmly, i assumed it had created valve/piston contact. But it was just stopping on the next lobe ?

    So, safe to turn back the cam gear the little bit counterclockwise with a socket wrench?

    Greg
    Sent from my SGH-T989 using Tapatalk 2
     
  13. BillyD

    BillyD Formula 3
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    #13 BillyD, May 20, 2012
    You're still fine, move the crank back so the front bank cam gear marks are lined up (u said u marked them right?). Turn the rear bank cams back to where they were marked & lock them down. Then continue on.
     
  14. JohnnyS

    JohnnyS F1 World Champ
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    #14 JohnnyS, May 20, 2012
    Yes, it is a small movement and the cam lobe isn't going to move the valve so much that you will do damage.
     
  15. Matto

    Matto Formula 3

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    #15 Matto, May 20, 2012
    Last edited: May 20, 2012
    Yep, you're just fighting the valve springs a bit at this point. Once you have your belts on and aligned with your marks, you can put the ratchet on your rear intake cam, then your front exhaust cam and bump them slightly clockwise (I literally just gently bump the ratchet handle with my hand....not enough to jump teeth :D). That should tighten up the long run of the belt and give you enough slack to slip your tensioner/idler bearings on and get the bolts in. Once both belts are to this point, double-check your marks, release the tensioners and give the crank two careful revolutions. At that point, you can tighten your tensioner bolts to the specified torque and you're good to go.
     
  16. Glassman

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    #16 Glassman, May 20, 2012
    Personally I'd rotate a few times and tighten each tensioner "only" when each is putting maximum pressure on the belt.
     
  17. greg328

    greg328 F1 Rookie

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    #17 greg328, May 20, 2012
    Thanks guys, I appreciate the wisdom--

    living and learning....

    Greg
     
  18. greg328

    greg328 F1 Rookie

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    #18 greg328, May 20, 2012
    I did not mark the front bank gears, the cover is still on.

    However, I marked the crank balancer position on the block, so I can get the motor exactly lined up where it was. I only moved it 1/2 inch or less when trying to gain tension on the long side of the belt..

    Shouldn't be an issue.....right???

    :)

    Greg
     
  19. mwr4440

    mwr4440 Five Time F1 World Champ
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    #19 mwr4440, May 20, 2012
    Last edited: May 20, 2012
    Stupid Question.

    How do you know the cams WERE timed correctly before starting? Doesn't sound like you did. All it appears you know is the valves and pistons did not meet in the same space and time.

    If I am correct and did not miss something, you might as well pop the valve covers and check the valve lash and index the cams.

    Do it all once and get it all "right."



    I am in the midde of that as I write this. Ain't hard, just a PITA.



    And lucky you, 31mm valve shims required in the 4V's are MUCH easier to come by.
     
  20. Glassman

    Glassman F1 World Champ
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    #20 Glassman, May 20, 2012
    Then you have a problem. If you did not mark the cam pulleys before removing the belts you will never know where to turn them back to, unless I'm missing something here.
     
  21. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #21 fatbillybob, May 20, 2012
    OP,

    Stop everything and think before you act. Think or learn how the enigne is supposed to turn and what happens will make your job easier.

    You sound like you have lost your referrence points so the safest thing to do is establish new ones. Take camshafts out this will allow valves to close and you can turn the crank and not hit anything.

    Now establish TDC with a dial gage and degree wheel

    Then set the cams back in on the cam cap marks and then the car will run fine at these assembly marks.

    You should go one more step and cam time the motor to verify that the marks are dead on. They could be off as the marks are for assembly not timing.


    look here: http://ferrarichat.com/forum/showthread.php?t=148604

    and here: http://ferrarichat.com/forum/showthread.php?t=148917

    These will get you started...good luck
     
  22. BillyD

    BillyD Formula 3
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    #22 BillyD, May 20, 2012
    Greg, yes, just move crank back to marks you made & put the car in 1st gear with e-brake on to lock it in place. Then move rear bank cams back to the marks u made & lock em down. As for getting that belt on, I remember having to have the tensioner off the car, installing the belt to marks(held with clamps, clothes pins, bankers clips, etc), then mounting the tensioner assembly(3 bolts), checking marks & then releasing spring tension(large center bolt).
    Bill
     
  23. greg328

    greg328 F1 Rookie

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    #23 greg328, May 20, 2012
    I still have my reference points . the pulleys and belt are clearly marked. the only issue is that my rear bank exhaust cam rotated clockwise about 3 teeth and stopped. i can still see all the marks. if it's safe to turn the cam gear BACK to where it was, then I'm good again.

    again, my front bank is still covered and untouched, and the crank pulley is marked to the block and has barely moved.

    Sent from my SGH-T989 using Tapatalk 2
     
  24. greg328

    greg328 F1 Rookie

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    #24 greg328, May 20, 2012
    Thank you FBB and billyd, good info.

    Sent from my SGH-T989 using Tapatalk 2
     
  25. greg328

    greg328 F1 Rookie

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    #25 greg328, May 20, 2012
    I did indeed mark the rear bank cams, belt and pulley. I'm crazy, but I'm not THAT crazy!

    It's the FRONT bank that remains covered and untouched. Again, with the crank marked against the block, I can line everything up as before no problem.

    Greg
     
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