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Thread: Spark blowout or something else?

  1. #1

    Default Spark blowout or something else?

    I'm running a 5.3 S480 setup. E85, LS2 non truck coils, MSD wires, BR7EFS plugs, gapped from .025" down to .015". Running up to 14 psi of boost. So I'm not quite sure if it's always been there, I'm starting to think it's gotten worse, but what I can say for sure. At .025" plug gap a definite problem, that's stock gap on these plugs (see datalog). This one definitely loses power, and sounds exactly like RPM spark cut rev limiter. At .020" last time ran good on a few strong pulls to 14 psi. Then from a dead stop at high RPM, had the same popping through the exhaust, nowhere near as much drop in power, but still a popping through the exhaust. At .015" gap I'm yet to see a problem. Questions I have:
    #1 Is spark blowout exactly like a spark cut rev limiter, or is it dependent on how bad the spark blowout is? I guess mine with .020" gap is very mild. Some people describe it as a misfire and way more violent on the car.

    #2 Is this likely a coil issue? They are old coils, from a 2005 6.0L.
    Holley does recommend max of 3.5 ms Dwell Time on these. I've always run 4.5 ms Dwell Time everywhere as that was just stock time if you don't setup a custom ignition on Terminator X.

    #3 I'm keen to buy the holley Smart Coils Big Wire kit, and make some new MSD leads. It's pricey, but will rule that out. Also keep in mind, I'm in Australia and cannot get truck coils here, just LS1 LS2 car coils. On milder ones, nothing can be seen on the datalog, only heard while driving and can feel power fall off a bit.
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  2. #2
    Join Date
    May 2014
    Bostwick, GA


    Quote Originally Posted by lscamaro234 View Post
    I've always run 4.5 ms Dwell Time everywhere as that was just stock time if you don't setup a custom ignition on Terminator X.
    Why not do a custom, and get the Dwell Time down into the 3s?
    I'm looking at the first screen shot. Near 3000 RPM, the AFR is 14, and the fuel psi is 40? What's the fuel psi base setting? Boost referenced? Why is the timing @ 30°? 200°F water temp seems high, for your application.

  3. #3


    Yes, boost referenced fuel pressure regulator, may have been set at 43 psi at this time at 100 kPa. 30° timing I run at 100 kPa and then start dropping it out fast at about 2 psi. What is an ideal water temperature? I have my fans set for Fan #1 @ 195°F & Fan #2 @ 205°F. Last time out, I've run 3.5 msec with .018" gap, seems to be OK so far.
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