Timing questions

Discussion in 'Technical' started by Tumbler, Feb 7, 2019.

  1. groberts101

    groberts101 Member

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    Thanks.. good to be acknowledged by some who can move past preconceived notions and keep filling their cups. Those boxes are cheap compared to standalone ECU/TCU offerings when it comes to the ignition curve portion of the whole deal. Imagine a locked out ignition curve with buku advance that keeps retarding from that point onwards and the map sensor stops the rate of retard based on manifold vacuum levels/engine load. You'll never come close to the same curve with a traditional weighted advance curve and vac pot arrangement.

    If you're really interested I'd be willing to fire up the old laptop and post a picture of my 11.5 to 1 compression 383 Chevy's 54 degree base timing(until retarding from about 1,700 rpm onwards) and high speed retard layout. Pretty interesting what amount of advance can be plugged into a more serious combo solely for the purpose of increasing manifold vacuum. If you can move you'r distributor around and gain additional manifold vacuum?.. then there is more to be had in that combo. Just a simple matter of how hard you want to work and what you're willing to spend cash and timewise to get it.
     
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  2. BBMS18

    BBMS18 Member

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    You’re welcome, my car does not have a engine at this point but if you don’t mind I will give you a shout this summer when I get it running and pick your brain on the subject.
     
  3. Krazy Comet

    Krazy Comet Tom Supporting Member

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    Why it's called "trial & error"
     
  4. groberts101

    groberts101 Member

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    No problem glad to help. Summer is my busiest work time so give decent lead time for replies and will do my best to help with advice or learning materials.

    You sure got that right, Tom. My blazer motor took weeks to dial in with back and forth ignition and fuel tuning. Laptop tuning the ignition makes the process much quicker but back and forth with carb tuning still takes time to reach maximum ignition spec's. In the bad old days it was back and forth between 2 toolboxes full of ignition and carb parts while sitting on the side of the road or parking lot to get things closer to perfected.

    For me the worst thing with trial and error is giving up and quitting the trial portion and ending up with greater error from an optimization standpoint. Sure makes for safer margins of error being further from the edge.. but still leaves extra power and efficiency on the table. Which is why I take occasional breaks from the trial and error process to keep from burning out or getting too frustrated.

    Later guys. Hope the OP gets his engine tuned for better than expected performance!
     
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  5. Tumbler

    Tumbler Member

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    I finally had enough time to put in the 10L reluctor and lighter springs, and it feels like a totally different engine. The throttle feels very close to normal, but not totally perfect yet. I'll still have to take time to dial it in. Right now it's at 14 degrees and it shows just under 22" of vacuum.

    I'll have to get used to driving it differently. At stop lights I'll give the amount of throttle I'm used to, and it'll start charging towards the car in front of me. It scares me a bit.

    There's another problem I'll have to fix before I can do much more. I timing marks have started jumping around. I was having this problem before, but it stopped once I soldered the connectors to the ballast resistor. There's a number of old, dubious splice connectors where the wires have been slowly slipping out. I'm hoping that cleaning these up might fix this. The idle and vacuum gauge are still smooth with this going on.
     

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