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Thread: Spark Latency table for MSD modules

  1. #1
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    Spark Latency table for MSD modules

    Not wanting to hijack the the 8 pin ignition modules thread, I thought I'd ask a question here.
    I have a MSD 8366 Pro-Billet dizzy, what are the latency tables that people use with the MSD module fitted in it?
    My 94 Chevy vans previous stock TBI dizzy had a 369 module in it and I've attached the spark latency table (presumably calibrated for the 369 module) that came with the vans original BDTZ bin.
    From what I've just read the MSD module may have latency characteristics more like an 048 module?
    Attached Images Attached Images

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    I hope others have some experience with this. When I was doing this on the dyno, it was with a GM Mefi computer and was the only time I had to do it as my customer went back to using GM distributors and he didn't want to have a rogue combination out there. It's been at least 10 years and have lost/crashed or had stolen a few laptops, but I will look this weekend for a file. I'm a lot better at backing up stuff now and also have a better way to keep files organized, that doesn't help with old files though.

    I'm still curious whether the latency has more to do with the ford style reluctor or the module or both.
    -Carl

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    R Bob has a good right up on TGO about latency and the amount of advance added along with how to test what u've got.its time consuming.I can't remember but I think 3 or 4 different latency setting for gm distributors.hth
    Jeeper
    87 sjimmy powered by a 92 cadillac 4.9L pfi on 7427pcm /700r4/ 8.8 3.55 rear/disc brakes.

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    I'll look for it unless you have a link handy. When I was doing it on the mefi I could program on the fly so it only took a few minutes to get it right.
    -Carl

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    I'm sorry I don't have a link.I can't figure out how to do that.so I took a screen shot.hope u can find the same write up.the latency part is quite a ways into it.Screenshot_2019-06-15-13-13-46.jpg
    Jeeper
    87 sjimmy powered by a 92 cadillac 4.9L pfi on 7427pcm /700r4/ 8.8 3.55 rear/disc brakes.

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    Your link just briefly spoke of latency. I believe this is the conversation you were thinking of. https://www.thirdgen.org/forums/diy-...ncy-table.html

    One of the guys in that thread mentioned he set the timing table to 20 degrees everywhere and adjusted the latency from there. Good idea but not on a 7747 style computer as it has a slope per 1k rpm and rpm limit for the slope...of course all that is programable but still needs to be noted and paid attn to. I'm not sure how many ecm's have that slope but 7747 (42) for sure. The mefi 1,2 computers have the same thing.
    -Carl

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    I didn't reread that but I believe you are correct.it's been a while since I looked at any of that.after the 7427 swap I just left it as stock.mostly because I could not find any of those settings defined for my application.
    Jeeper
    87 sjimmy powered by a 92 cadillac 4.9L pfi on 7427pcm /700r4/ 8.8 3.55 rear/disc brakes.

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