question on 575 cam timing | Page 2 | FerrariChat

question on 575 cam timing

Discussion in '456/550/575' started by stevepaa, Oct 17, 2017.

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  1. fatbillybob

    fatbillybob Two Time F1 World Champ
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    This is the reality despite what the service writers will tell you. When I apprenticed in the 70's all the cars got belt swaps on assembly marks. That was "timing". The only cars that got real cam timing were the rich guy trackcars and vintage track cars. I remember the 1st cam timing I watched done by Lyle Tanner's chief mechanic on a race dino. I said hey that number does not look right. JD said yeah I use different numbers on the racecars because I know what works to get more out of them. You got a bonus today...don't write it down and don't tell anyone either.
     
  2. stevepaa

    stevepaa Formula Junior
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    I read your post to understand that Ferrari specs are in camshaft degrees not crankshaft degrees
    https://www.ferrarichat.com/forum/threads/degreeing-cams.148917/

    I did install a degree wheel on crank and I am reading crank degrees.
    John's graph shows exhaust open at ~250° before TDC and close at ~70° after TDC
    I have exhaust open at 60° before BDC which is 240° before TDC and exhaust close at 66° after TDC
    John's graph shows intake open at ~30° before TDC and close at ~290° after TDC
    I have intake open at 14° before TDC and intake close at 112° after BDC which is 292° after TDC

    John used corrected as he found the same situation as I did. The intake should open before TDC not after and that exhaust should close after TDC not before

    My camshaft marks are now almost exactly where they were when I disassembled. Five years ago at last belt change at the shop they did degree the cams Image Unavailable, Please Login
     
  3. stevepaa

    stevepaa Formula Junior
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    Maybe the Ferrari specs are in crank degrees to be measured at 0.6mm lift and it is just happenstance that by doubling the spces I am getting close?
     
  4. fatbillybob

    fatbillybob Two Time F1 World Champ
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    I use assembly marks as a check. When I did lobe centerline method ala 350 chevy motors you get marks dead on because the accuracy just isn't there with that method...we all evolve. Actually, Pete got me really thinking about 550 cam timing. When I do things the Ferrari way we start to see exactly what you see very close to assembly marks (taking dwell out of TDC too). So after your timing is done you get 4 marks close like that I call it good and trust my cam timing.

    Now honestly can you feel the difference between lines on the assembly marks or cam timing with degree wheel? NOT me. I race cars at the highest amateur level and raced a 348 for a few years before that. I messed with cam timing but my track skill level was not good enough to get reproducible laptimes lap after lap so I could never prove my adjustments in cam timing with a stopwatch. Today I have that consistency as a racecar driver but not the patience to test how many 10ths faster my 550 is with proper cam timing vs. assembly mark timing, vs. some other perceived better cam timing. Do I still use a dial gauge and degreewheel? Yes, every time I take the belts off. I also never use the factory hand scribed lines on the back of my heads. There is no way with parallax error that doing the back of heads scribe lines are any better than lobe centerline eyeballing. So in my mind you go with assembly marks (what the shops really do) or you time the Ferrari way.
     
  5. Dave rocks

    Dave rocks F1 World Champ
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    I recall Brian's comments about cam timing vividly. He stated that Ferrari terms TDC at the start of the dwell, not the middle. I've measured a 355 engine dwell and it's exactly 1 degree (this will vary based on manufacturing tolerances). So, in that example, we are talking about 1/2 a degree if you do the Ferrari method or the universal meaning of TDC. that 1/2 of degree is not going to mean anything.
     
  6. stevepaa

    stevepaa Formula Junior
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    at .61 mm lift I get
    intake open 7° after TDC close 53° after BDC
    exhaust open 32° before BDC close 11°after TDC

    so the intake does open at -7° BTDC for the .61 mm lift

    I would like someone who has actually degreed their cams on a 575 to offer some insight.
     
  7. tazandjan

    tazandjan Three Time F1 World Champ
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    Remember that on a 575 (and 612) there are scribe marks on the back of the cams, too, that are a good check on whether your timing matched the factory's. Need a mirror to see them since it is pretty tight back there. Original timing was done before engine installation, so a little easier to work back there for the factory.
     
  8. stevepaa

    stevepaa Formula Junior
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    I looked at scribe marks, while both RH front marks are dead on, aligning these RH rear would advance timing for both intake and exhaust for RH bank. LH bank marks look much better. Are these rear marks put on after an assembler actually degrees the camshafts?
    Image Unavailable, Please Login Image Unavailable, Please Login
     
  9. tazandjan

    tazandjan Three Time F1 World Champ
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    Steve- Affirmative, they are. The front marks are assembly marks to guarantee you do not bend a valve while assembling. Question becomes how accurate are the rear marks depending on who degreed the cams at the factory? From the WSM:

    In the event of camshaft replacement, restore the rear reference marks as they have been made manually during
    assembly. The same instructions hold for the reference marks on the driven pulleys in the timing system.


    The cams come with the front assembly marks if they need to be replaced, but obviously not the rear timing marks. Note this was done before engine installation, so applying those marks with the engine in place would be a challenge. There is a tolerance on the lift, so that may be all you are seeing.

    Depends upon whom you trust, yourself or Luigi at 4:30 on a Friday afternoon.
     
  10. fatbillybob

    fatbillybob Two Time F1 World Champ
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    I have found the rear marks to be spurious. Anyone who has tried to mark things with a chisel knows how difficult it is to be perfect. To be perfect on cam timing is even more difficult. The only way to perfectly score the rear of the head is to chisel on the camshaft and the cap at the same time. That would be not good because you move material that will bind and gall on each other. That's why all the rear marks are 2 strikes. You can see this is the case by the angle of each line. Neither of those line pairs line up under any conditions. And if you find TDC the Ferrari way do the rear marks come closer now? Anyway people know I have always been against using the rear marks. If people really want to have a faster check on cam timing IMO they should personally cam time and then use the line on the camshaft front and make a better dot on the 1st cam cap with a centerpunch. This way you can get direct vision on your target instead of have parallax error leaning over the front 4 ft of car and squinting in the dark trying to see the rear lines. Also, you would still have the assembly marks so a new comer to your car would be thrown off by the modification.
     
  11. stevepaa

    stevepaa Formula Junior
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    Does anyone have any thoughts on the Ferrari WSM method expecting intake and exhaust to have same lift around 18° after TDC. And intake to have no lift at TDC.
     
  12. Dave rocks

    Dave rocks F1 World Champ
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    Those rear marks don't even look as if they were done at the same time with cap and cam assembled.
     
  13. tazandjan

    tazandjan Three Time F1 World Champ
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    FBB- Those rear marks lined up perfectly after my 575M had the cams degreed. Not found on a 550, unless the very late ones had them.
     
  14. stevepaa

    stevepaa Formula Junior
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    #39 stevepaa, Oct 25, 2017
    Last edited: Oct 25, 2017
    Terry
    If you can ask your mechanic how he would align these slanted marks and what method did they use to time the cams?
    I see three methods,1) first lift 2) lift at .061mm where duration is measured or 3) WSM at18° ATDC ( which I cannot even fathom the correctness of).
    And of course, which specs did they use?

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  15. fatbillybob

    fatbillybob Two Time F1 World Champ
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    Here is my 2001 550 rear cam lines are there... I can't remember if they were on my 2000 550. I don't use them so don't even think about them. Image Unavailable, Please Login
     
  16. tazandjan

    tazandjan Three Time F1 World Champ
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    Steve- My guys went straight by the WSM method. Marks all lined up after that. Next time we will probably just do a lock and swap.
     
  17. stevepaa

    stevepaa Formula Junior
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    Well, I will try that WSM method again later today. My mind just cannot see how there is 1.5 mm of lift left on exhaust at 18° ATDC.
     
  18. Dave rocks

    Dave rocks F1 World Champ
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    1) I'm not very familiar with a 575 as I own 355's. But, I'd been thru this with 355's.

    I just scanned the 575 WSM briefly and see that it states the piston will be 2.43mm down when 18 degree ATDC (never saw a piston stroke measurement related to timing prior). But, at that point, the WSM states a value of 1.51 to 1.66mm for the valve lifter. So, it would seem you are within spec - right?

    Maybe I'm missing Image Unavailable, Please Login something?
     
  19. stevepaa

    stevepaa Formula Junior
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    Then it says to move to exhaust side, keep on cranking and get 1.51 mm lift on exhaust valve as it closes. At18° ATDC the timing diagram from Cribb indicates there should be only 0.20 mm lift on exhaust. That is my puzzlement.
     
  20. stevepaa

    stevepaa Formula Junior
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    I measure 0.3 mm when exhaust closes after 18° .
     
  21. stevepaa

    stevepaa Formula Junior
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    #46 stevepaa, Nov 1, 2017
    Last edited: Nov 1, 2017
    I set all camshafts to assembly marks.
    Then I measured lift for #1 intake and exhaust and #12 intake and exhaust
    Curves lie on top of each fairly nicely.
    I do not have software to pick off data points so I eyeballed as best I could for durations.
    I got 207° duration @ 0.050" lift and 225° duration @ 0.24" lift for exhaust valves
    and 204 Image Unavailable, Please Login ° duration @ 0.050" lift and 228° duration @ 0.24" lift for exhaust valves

    And from graph, I get ~1.42 mm at 18° ATDC
    I will confirm lift at 18° by measurement of piston displacement
     
  22. stevepaa

    stevepaa Formula Junior
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    I got 1.36 mm intake valve lift at 2.43 mm piston displacement on #12. And 1.25 mm on #1. So I need to adjust intake cams slightly. I still have no clue how to set up exhaust cams. I may move them same as I do for intake.
     
  23. stevepaa

    stevepaa Formula Junior
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    And the other issue I have with the WSM is the statement that there should be zero lift on intake valve at TDC just before intake valve open. The intake valve opens before TDC by ~10°. Moving cams to have lift of 1.5mm at 18° will further advance the lift at TDC.
     
  24. stevepaa

    stevepaa Formula Junior
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    On intake #1 I moved cam wheels one hole counter clockwise and now have 1.52 mm intake lift at 2.43 mm piston. I moved exhaust the same. You can see on pic I marked with a white dot the holes when I did the lift measurements. Now plugs are one hole over
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  25. stevepaa

    stevepaa Formula Junior
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    RH intake cam is now dead nuts to marks in front, there must have been some slight slack in belt when I set it before.
    RH exhaust cam edge of mark is middle of cap mark.

    rear marks still off by a few degree, and with the angle they were scribed , good luck deciding on proper alignment
     

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