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Carburettor syncronizing "tool".

Discussion in '365 GT4 2+2/400/412' started by hoverland, Dec 20, 2011.

  1. hoverland

    hoverland Formula Junior

    Aug 14, 2010
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    Harald Ø
    #1 hoverland, Dec 20, 2011
    Last edited by a moderator: Sep 7, 2017
    On my -77 400 and on all multicarburettor engines syncronizing the carburettors can be a challenge to your patience. Not rocket science, but it takes some time and skill to get it all right as you need to compare all 12 every time you adust a tad. There's a lot of engines that is not running as smooth as they should because owner is reluctant to get them done!
    But the reward is the hair-raising, addictive sound of a carburetted V12 in perfect harmony, from idle to open throttle.

    In order to make it easier for myself and my friends with exotic engines, I'm putting together an instrument to compare vacuum in each inlet via the "testport blindscrews".
    I've used generic ("manifold air pressure") MAP sensors and a simple software to display pressure in each inlet barrel. So comparing the level on all 12 is a breeze.

    Attaching picture of prototype board beside a matchbox to visualize the compact size. Pls note that software screenshot is for illustration only.
    At the moment I'm changing my exhaust manifolds so it will take some days before I get to make a proper test.
    Will post results.
    Harald
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  3. kliko312

    kliko312 Karting

    May 21, 2008
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    Wow, very impressive!

    Did you design this by yourself? I could use a similar device for my 365 as well.

    Keep us posted on your progress. Good work!
     
  4. blkprlz

    blkprlz Formula 3

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    +1!
     
  5. alastairhouston

    alastairhouston Formula Junior

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  6. Fave

    Fave F1 Rookie
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    Sounds like an electronic manometer. Very cool
     
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  8. alberto

    alberto Formula 3
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    Now that's very interesting. Please post more about your efforts. I'm very interested.
     
  9. hoverland

    hoverland Formula Junior

    Aug 14, 2010
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    Harald Ø
    Thanks
    The basic idea was to use manometers, but comparing 12 gauges? Thats not a simple tool to use!! This device will use 3mm id hoses, so the whole thing will be rather neat :) Designing a nice casing for it now.
    A good friend with superb electronics skill has drafted the circuitboard and writes the software. I'm just an "analog" guy with the ideas.

    Yes the device can be used for any engine/layout. Option in software to enter any sensor sequence/engine layout; (V12 (double six), V8 (double four), straight eight, straight six......

    Working on some better graphic presentation in software to make it easier to "see" which individual cylinder or cylinderbank to adjust.
    Also pressure range is automatic so it adapts to accomodate for max/min values continously -so as you are getting closer with adjustments on engine the display gets more and more accurate. This to avoid need for any fiddling with computer while adjusting engine, and allows for revving engine to check/adjust throttle linkage as well.

    Harald
     
  10. solofast

    solofast Formula 3

    Oct 8, 2007
    1,773
    Indianapolis
    With 12 independent sensors, how are you going to calibrate to insure that they are within a reasonable range?

    When you have one sensor, you don't need to calibrate it, you just use it. Manometers don't need calibration, you just line them up, but a electrical sensor needs to able to be calibrated. Maybe you can attach them all to a common source and see what you have and calibrate from there, but you've got to come up with something to make sure the sensors aren't drifting all over the place.

    Also, are you going to attach some type of venturi on the inlet stack to get higher velocities (like is done on a unisyn) to make the flow more readable, and if so you need to make sure all of the venturies are the same.

    Neat idea, but a unisyn works just fine, even though it is a bit cumbersome to use on a 12 cyl engine. But you don't have to calibrate it, and it's reliable.

    I've synched Webers by ear for years. I had a friend challenge me that I couldn't do it by ear. I turned my back and let him dork with all the mixture and synch screws that he wanted to, and then I reset it all by ear. Once I got it all smoothed out and right, he put the Unisyn on it and to his dismay, they were all perfectly matched (this was six 2 barrels, so not as tough as 12 singles). You just need to know how to tune out the lope and miss, and after a bit you are there. A Unisyn makes it quicker, but the old timers used to do it by ear and an experienced guy could make your car humm. Nowadays we want technology to do everything for us, not sure if that's really better. Cool toy though.
     
  11. hoverland

    hoverland Formula Junior

    Aug 14, 2010
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    Harald Ø
    Thanks for good questions.
    The linear accuracy for the sensors is within 1,5% so I expect this to be well within acceptable tolerance for carburettor adjustment, sensors will be calibrated with ambient pressure of the day before engine start -right?
    If it proves to be a problem -I will get a calibration feature for a vacuumvalue as well in the software.
    The software will show bars "mid screen" regardless of actual value, the range adapts so I expect OK readings directly from testports.
    Will keep you posted as my testing progresses.
    I'm aware that the difference between theory and practise is that; in theory -there is none !

    And to my experience -manometers do need to be calibrated! -more than modern sensors, I would say.
    Unisyn is a good tool for idle check, but needs to adjusted for airflow when RPM changes, so throttle linkage check is not easy -and you need ample space/access to all carburettor inlets.

    Of course -I really admire the experienced oldschool mechanics that does this by ear, but you guys are hard to find !!
    Most of all I enjoy good tools, and if modern technology can be used to make this more precise and easier for inexperienced hobbymechanics like myself -I'm happy to use it -even on my "analog" cars.

    The idea is to have capped nipples in testports permanent -so taking off caps, connecting hoses and make a verification is done in a few minutes.
    Harald
     
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  13. tomberlin

    tomberlin Formula Junior
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    #10 tomberlin, Dec 21, 2011
    Last edited by a moderator: Sep 7, 2017
    Your project looks like it has great potential. I would be interested to know if you have a wild idea on projected cost.
    While working on my 308 I used these CarbStyx- made for 4 cylinder motorbikes. I thought they worked great at any engine speed and as far as I can tell they don't need to be calibrated.

    Not my photo.

    Cheers,
    TomB
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  14. vespasian

    vespasian Karting

    Nov 28, 2011
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    Awesome project!

    Do you plan to do a "mini series" of the tool so some users here could share production costs and get their own tool?
     
  15. hoverland

    hoverland Formula Junior

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    #12 hoverland, Dec 22, 2011
    Last edited: Dec 22, 2011
    Thanks for picture, those types have "calibrated" inlet orifices, and with those long tubes I guess they are fixed. 12 of these long tubes could have done the same trick I'm trying to do :) Showing all 12 at once for direct comparison and allowing for variations RPM.

    I have used a similar one (with shorter tubes though) made for the Honda CBX straight six with good results.
    The CBX tool, had adjustable orifices and needed to be "calibrated" by connecting one by one to same vacuum source and adjust until all balls at same height.

    Regarding cost, -the circuitboard itself is cheap, so I'm getting a few extra anyway.
    Whats driving the cost are the sensors/components on the CB, and maybe a sexy casing. As far as I know you need to order electronics in thousands before you get any significant discount on those.
    Will post update :)

    Harald
     
  16. Fave

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    Lol, I made one for my bike. Cost about $3 and a pot of tea. Used the tea as the balancing liquid so it can be easily seen. And if it gets sucked into the carbs it won't so hurt them ..... Much :)
     
  17. Flinch

    Flinch Formula Junior

    Nov 15, 2009
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    Peter El Cheapo
    throwing money at the screen, but still no order confirmation :D

    VERY interested in the results. Keep us posted!
     
  18. Far Out

    Far Out F1 Veteran

    Feb 18, 2007
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    Harald, great project. I have something similar in mind - sensors with higher dynamics would allow for very interesting carburettor and engine diagnostic features if they measure the pressure with a high time resolution.
    At the institute I'm working, there is a lot of knowledge of how to detect and identify faults from the wildest signals (like one guy 20 years ago who managed to implement a cylinder individual knock detection from the exhaust gas pressure signal), so I have that part covered.

    However, my problem is that I haven't found affordable sensors yet which deliver the performance needed. 100Hz isn't going to cut it, and spending four figure sums just on one sensor isn't a good idea either. Maybe we could exchange some ideas!
     
  19. hoverland

    hoverland Formula Junior

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    Harald Ø
    Sounds interresting, please PM me.
    Harald
     
  20. hoverland

    hoverland Formula Junior

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    Harald Ø
    #17 hoverland, Jan 2, 2012
    Last edited by a moderator: Sep 7, 2017
  21. hoverland

    hoverland Formula Junior

    Aug 14, 2010
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    Harald Ø
    Update
    First test successful -but modifications in software needed.

    The test was a bit limited as the software did'nt handle neither the fluctuations nor the dataflow from multiple sensor very well.
    We fix -said the software guru, and I know he will ;)

    Here's a short video showing test of one sensor, addition of a new "timeline-view".
    http://youtu.be/ydMquZ-O8Uo

    Next update when software OK

    Harald
     
  22. swift53

    swift53 F1 Rookie
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    I am seriously interested.
    Please advise and great work!

    Regards, Alberto
     
  23. kliko312

    kliko312 Karting

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    Good job!
     
  24. hoverland

    hoverland Formula Junior

    Aug 14, 2010
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    Harald Ø
    Thanks all for positive comments

    The software issue is pinpointed by the softwareguru and beeing rewritten, filtering/variable sampling rate will also be added in software to handle fluctuations.
    The very good thing is that the hardware, circuitboard/components is performing excellent :)

    Thinking ahead, the "Timeline" function can be used while driving -logging variations under acceleration/decceleration to a file. I guess it can be possible to diagnose quite a few things ie pistonring leak, valve leak and more in addition to carburettor sync?

    I'm on travel now, so next test will be in a few weeks.
    Keeping you posted.
     
  25. hoverland

    hoverland Formula Junior

    Aug 14, 2010
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    Harald Ø
    All hooked up and working.
    Let me first say that engine was -before hooked up, synched pretty well with STE flow meter and by ear, running "not so bad actually".

    First video shows what I expected, -engine running smooth -but carburettors a little "all over the place".
    Second video shows after quick tuning -mid carb on one cyl row still a little to high.

    http://youtu.be/nNWEGW9O90g
    http://youtu.be/6u7JZSMrR4o

    As you can see -need to dial in software a bit more with regard to range and averaging.
    Maybe "autorange" was not such a brilliant idea after all? -as the pressure fluctuates more that anticipated at idle when inlet valve opens/closes.

    Harald
     
  26. vespasian

    vespasian Karting

    Nov 28, 2011
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    Harald,

    I'm totally amazed! Not only by this marvellous tool but also by your engine compartment - I'm really envious there! ;-)

    Apart from some tiny scaling and adjusting work on the graphs, I can't see why you shouldn't be deeply impressed by yourself!

    And the big question of course is ... how can this tool be multiplicated and purchased by carb-desperated guys like me?!

    Alex
     
  27. Crowndog

    Crowndog F1 Veteran
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    Wow very sensitive huh. May want to damp the response a little.
     
  28. vespasian

    vespasian Karting

    Nov 28, 2011
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    Alex
    What kind of problem do you have? If this is my opinion, then I'll write it down.
     

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