Captain Obvious

Ignition Timing Mechanical Advance

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    6 hours ago, jonbill said:

    It comes from Tuner Studio (I'm a tuner too, u get me bro?)

    In a stock engine I guess the action starts around 2500, so I think the rising VE and likelihood of knocking is probably why the ignition curve stays flat.

    Maybe in theory one could start adding more advance again after the the torque/VE peak is passed, but that's would be very hard with springs and weights!

    I get you bro.  LOL   !!

    And I agree with your assessment about the rising VE. And also agree that would be very difficult with springs and weights.

    Maybe I could whip up some little programmable device to try that. With the state of world events, I guess I have the time to work on projects at home...

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    Most welcome CO. Those are brilliant links / read you found - my hours of insomnia can be quite informative going through that. (It’s 04:15 here )

    Re. The state of the world as is, I don’t think I’ve done this much intensive work on the house as I have been of late. Even been fixing the roof in between monsoon like showers. My wife is also on indefinite working from home and the school just wrote to say they may close physically and go google classroom next week. Quarantined with the kids!? Arrrrrghhhhh!

    f4e6896013b41710f2ff8a9271632b38.jpg

    Next job is to get the ignition timing right on the Z ;). If only!!

    Back on topic, it’s interesting that some of those guys are taking timing away as the curve flattens. I was always told 1 degree extra per 1000 rpm after the curve goes flat. Will have to try the taking away timing thing on the next RR session.

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    9 hours ago, AK260 said:

    Next job is to get the ignition timing right on the Z ;). If only!!

    Right.

    Her - "Hey, honey... The zombie apocalypse is coming. What should we do?"

    Me - "Well I don't know what you're gonna do, but I'm gonna stay home and work on my Z."

    :ph34r:

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    Right.
    Her - "Hey, honey... The zombie apocalypse is coming. What should we do?"
    Me - "Well I don't know what you're gonna do, but I'm gonna stay home and work on my Z."




    ROFLMAO - STC!!

    Funny you should say that, I’m about to turn this ....

    0138c3fe8ff93627ad10c711b0de1ec7.jpg

    Into one of these ....

    c5b907e5e8e7a4036b4bc61d2977b1b0.jpg
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    Cool. Just make sure you're careful if there's any fluorocarbon (for example... Viton) in there. Don't get it too hot.

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    @AK260, So a little bit ago, you suggested that the optimum crank position for peak pressure was 22 degrees ATDC, but the articles we've bantered around suggest that 14 degrees ATDC is optimum.

    Do you know the origin of your 22 degree suggestion?

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    I think it was JonBills that said 22 degrees first in this threat - I merely echoed. I blame Jon :p

     

    But you are right most articles say 14. Having said that I have read 22 degrees somewhere else’s also!

     

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    7 minutes ago, AK260 said:

    I think it was JonBills that said 22 degrees first in this threat - I merely echoed. I blame Jon :p

    OK. Then I blame Jon as well. Works for me.   LOL

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    Yes, it was me. I think I did caveat it at the time. Back then it didn't seem important to get the detail right :)

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    I love Kelvin and Hobbes.  Great cartoon.

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    So I've been browsing around the internet watching car videos and came across this guy who has a channel where he finds old cars and builds engines and stuff, and he built one then took it to the dyno for tuning.  A Chevy 307.  Guess what "best" timing was?  Weird.

    It's at 31:30

     

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    Thanks for that. So I'm assuming that 34 degrees was total timing? But on the dyno at WOT, that would be all mechanical, right? No vacuum.

    And our engines top out at just over half that for the "base" mechanical. Sounds low.

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    And on a related note, I've whipped up a little electronic gizmo prototype that applies the mechanical advance in an electronic manner. Reads an input pulse train and effectively outputs a pulse train advanced with respect to the input. The curve looks like the stock curve with a couple adjustments to the numbers to make the math work out easier.

    10 degrees advance up to about 1200 RPM
    Then 1.3ms of delay from 1200 up to 2500 RPM (which mimics the advance slope of the stock curve)
    And then caps off at 19.5 degrees above 2500 RPM

    Not sure there's any real value in what I did, but it was an attention diverting academic exercise. I think just that is worth something right now.

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    10 hours ago, Captain Obvious said:

    And on a related note, I've whipped up a little electronic gizmo prototype that applies the mechanical advance in an electronic manner. Reads an input pulse train and effectively outputs a pulse train advanced with respect to the input. The curve looks like the stock curve with a couple adjustments to the numbers to make the math work out easier.

    10 degrees advance up to about 1200 RPM
    Then 1.3ms of delay from 1200 up to 2500 RPM (which mimics the advance slope of the stock curve)
    And then caps off at 19.5 degrees above 2500 RPM

    Not sure there's any real value in what I did, but it was an attention diverting academic exercise. I think just that is worth something right now.

    WOW VERY COOL BRUCE!!!!!!

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    Haha!! Yeah, if I put in some provision for vacuum advance, I've re-invented the electronic ignition controller for the n+1000th time!!   LOL

    Completely remove or lock down the mechanical and vacuum advance mechanisms in the distributor and do it with a little module instead. I'll let you know when I've reached the point where I'm willing to put this thing on my car and take it for a drive. Haha!

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    The design concept is three pulses per crank revolution. Right now it's just using a signal generator on the bench for proof of concept, but if I get energetic, I'll put a variable reluctor front end on it and connect it up the pickup coil on a distributor.

    In theory, it should work with points. All the math is set up for six cylinders and three pulses per crank revolution. I can get those pulses from either points, or the VR pickup in the later distributors.      In theory.   Haha!!

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    So I did some reverse engineering of the stock ignition module and patched my contraption into the middle of the box, essentially using the stock module as my VR front end. Then I spun up a distributor on the bench with a variable speed DC motor. And it all seemed to work as intended!     :geek:

    Hey... I got the time, right? It's not like I can drive my car!

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    I’m impressed....maybe during this global pandemic you can find a way to make something you can sell later that’s not $549 like 123 ignition.  Making good of a bad situation at Bruce’s house.  Most of America is watching Tiger King and putting on pounds while the Mad Scientist is building contraptions in his garage.  If you can figure out of to make TP out of tree bark you’ll be the next Jeff Bezos. 
    in all seriousness, nice job Bruce, keep pushing the envelope for the great good of Z owners.  

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    Thanks bud! I didn't start messing around with any of this stuff with the intention of producing anything for sale, but if someone wants to pay me, I'm for sale. Haha!

    And speaking of such things... So remember the other day when I told you I broke that brittle plastic vacuum advance bearing holder? It was right after I walked you successfully through how to get YOURS out WITHOUT breaking it?   :cry:   :
    P1160612.JPG

    Also remember that I told you I was sure that (using stone knives and bearskins) I COULD probably make something to replace it, but there was no way I was going to go through all that trouble? It was way beyond my pain threshold for an academic exercise?

    Well, then there's now:
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    It's not brittle anymore.  :victorious:


     

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    I also made a plate to lock the vacuum advance mechanism down hard so I could spin the distributor on the bench without worrying about the plates slipping around inside. There are several threads on HybridZ that talk about the advance mechanisms. Here's a couple links. John Mortonson seems to be a big champion of jettisoning the vacuum advance completely and bumping the static base advance up instead. He JB Welded the plates together completely:

    I didn't want to epoxy everything together, so I made this instead:
    P1160685.JPG

    P1160689.JPG

    Not ready for production, but works for locking my distributor together on the bench!

     

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