I went in for a 5k major, it cost XXXX more and here's what happened" | Page 8 | FerrariChat
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I went in for a 5k major, it cost XXXX more and here's what happened"

Discussion in '348/355' started by johnk..., Dec 13, 2017.

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  1. taz355

    taz355 F1 Veteran
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    #176 taz355, Dec 20, 2017
    I am talking about the cams and timing not so much the cranks.
    Although after saying that I remebered our engines dont have shim under or over bucket designs so the hydraulic lifter would play a part for sure.
     
  2. Dave rocks

    Dave rocks F1 World Champ
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    #177 Dave rocks, Dec 21, 2017
    Grant - The cams, valves, etc are a relation to piston TDC. The con rod tolerances will play a role in that. Many parts play a role in the stack up.
     
  3. johnk...

    johnk... F1 World Champ
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    #178 johnk..., Dec 21, 2017
    Dave, the con rod tolerances will not play a roll in where TDC is. All they will do is determine how high the piston moves up to reach TDC. The only effect will be a (really) insignificant change in the ratio of chamber volume to swept volume.
     
  4. Dave rocks

    Dave rocks F1 World Champ
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    #179 Dave rocks, Dec 21, 2017
    John - not true. My comment is based on my prior post of timing 1 cylinder per bank and assuming the other 3 will be exactly like the first. In that case, it certainly will effect it.
     
  5. steved033

    steved033 F1 World Champ
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    #180 steved033, Dec 21, 2017
    ...for the low low price of 3k

    sjd
     
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  6. johnk...

    johnk... F1 World Champ
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    #181 johnk..., Dec 21, 2017
    No. TDC is not a function of C-rod length. If you checked the other 3 cylinders and they were different, it would not be because the c-rod were of different length. It would be because of some rotational variance, not a linear one, like errors in finding the angular position of TDC, of which the Ferrari method leaves a lot to be desired, or angular tolerance of the crank throws and cam grind or cam lobe wear.

    For example, if the crank was not exactly a flat plan deal, cylinders 1 and 3 may not achieve TDC at the same crank angle. Likewise, cylinder's 2 and 4 may not achieve TDC at the same crank angle they may not be exactly 180 degrees from 1 and/or 3.

    What does change with c-rod length, besides the linear position of the piston in the bore, is the rate at which the piston moves (piston velocity) for a given angular velocity of the crank, and hence, how long the piston remains within a specified angular range of TDC, TDC +/- alpha.
     
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  7. Dave rocks

    Dave rocks F1 World Champ
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    #182 Dave rocks, Dec 21, 2017
    John, if you set TDC on cylinder 1, time the motor perfect and assume every single component is exactly the same but the con rod, and the con rod of cylinder 2 is a different of .002", the timing will be off some angular amount when you reestablish TDC at cylinder 2. I'm not suggesting TDC will be off as TDC is the base line in which you set zero.
     
  8. INTMD8

    INTMD8 F1 Veteran
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    #183 INTMD8, Dec 21, 2017
    Unless there is something I'm missing, agree with John on this one, his explanation is correct.

    Another example would be if you establish TDC on cylinder 1, zero on degree wheel.

    Remove the connecting rod and replace it with a one inch shorter connecting rod I see no reason that TDC as found with a piston stop or dial indicator would not come up the same, with no adjustment of the pointer/wheel.
     
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  9. Dave rocks

    Dave rocks F1 World Champ
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    #184 Dave rocks, Dec 21, 2017
    Yep - you guys are correct - brain freeze from working too much. The angular relationship of each rod journal (crank) would need to be off the theoretical position to effect this. Sorry for the false posts. I need some sleep ;)
     
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  10. INTMD8

    INTMD8 F1 Veteran
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    #185 INTMD8, Dec 21, 2017
    Sleep helps! I'm going to try to hibernate for a few weeks before starting my header build, brain is starting to hurt just thinking about it :D
     
  11. johnk...

    johnk... F1 World Champ
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    #186 johnk..., Dec 21, 2017
    Well I see that you have yielded, but for completeness I will just say that TDC would be the same. Just that the piston with be 0.002" further up in the cylinder when at TDC.
     
  12. INTMD8

    INTMD8 F1 Veteran
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    #187 INTMD8, Dec 21, 2017
    Or .002 lower :D
     
  13. johnk...

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    #188 johnk..., Dec 21, 2017
    Well.....yea. :)
     
  14. Dave rocks

    Dave rocks F1 World Champ
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    #189 Dave rocks, Dec 21, 2017
    Yep - you guys got me good. What can I say - 70+ hours for nearly 2 years is taking it's toll. Paint fumes probably havn't help much either LOL ;)

    But, other tolerances do matter - I'll think about them after a good nights sleep :)
     
  15. johnk...

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    #190 johnk..., Dec 21, 2017
    Dave, I was loaded for bear. Spent 20 minutes building a spread sheet showing the difference in piston motion and how sensitive the motion near TDC is to angular position as a function of C-rod length. Now I'll never get to use it on the battle field. But it's good that you surrendered before I had to deploy my weapons of mass destruction. :rolleyes:
     
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  16. INTMD8

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    #191 INTMD8, Dec 21, 2017
    Loaded for bear, lmao :D
     
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  17. Dave rocks

    Dave rocks F1 World Champ
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    #192 Dave rocks, Dec 21, 2017
    Jim, I gave in far too soon. I should have made John follow thru with his spreadsheet. But, can't stump the grump :D ;)
     
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  18. taz355

    taz355 F1 Veteran
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    #193 taz355, Dec 22, 2017
    So is anyone going to put up the seals you guys are talking about that some think should be changed each time. I just want to be sure I understand.
     
  19. plugzit

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    #194 plugzit, Dec 22, 2017
    I was so looking forward to a war between an engineer and a machinist!
     
  20. Dave rocks

    Dave rocks F1 World Champ
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    #195 Dave rocks, Dec 22, 2017
    Nope, Bruce. It was a war between 2 engineers, one of them (me) just happens to own a shop ;)

    But, when it comes to theory, John will mop the floor with me :D

    This one has made me look pretty bad though as it was just super obvious :)
     
  21. Nader

    Nader Formula Junior

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    #196 Nader, Dec 22, 2017
    There are four types of posts about the 355:

    1. It's so beautiful (no argument from me)
    2. It sounds amazing (ditto)

    which leads to

    3. Here's a video of my 355 with aftermarket exhaust sustaining redline in a long tunnel

    which leads to

    4. a. Question about "slow down light"
    b. Question about CEL
    c. My headers melted
    d. I went in for a $5K major, but it cost XXXX more and here's what happened...
     
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  22. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #197 fatbillybob, Dec 22, 2017
    LOL! I was just buttering my popcorn. JK is the 10 point buck today.
     
  23. yelcab

    yelcab F1 World Champ
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    #198 yelcab, Dec 22, 2017
    I would pit your real life knowledge up against any engineer's mental masterbation any day of the week, Bruce.
     
  24. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #199 fatbillybob, Dec 22, 2017

     
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  25. Dave rocks

    Dave rocks F1 World Champ
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    #200 Dave rocks, Dec 22, 2017
    :rolleyes::rolleyes::rolleyes:

     
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