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Thread: Looking for Help with Atomic EFI settings

  1. #21

    Default Looking for Help with Atomic EFI settings

    Guppy80 wrote:
    As a side question, does MSD supply, or offer extension cables for the Atomic handheld unit? I would really love to have the unit in the car connected at all times, but since the Atomic ECU is mounted on the inner fender behind the Driver headlight, that's pretty much impossible with out some sort of extension cable.

    We do offer three CAN Buss extension cables...

    PN 7782: 2-ft extension

    PN 7784: 4-ft extension

    pn 7786: 6-ft extension

  2. #22

    Default Looking for Help with Atomic EFI settings

    Guppy80 wrote:
    The timing is being controlled through the Atomic EFI which is connected through the MSD 6AL ignition box, that is wired into the HEI distributor, which if I recall correctly, the mechanic said he opened the distributor and removed something from it and wired in the 6AL ignition box and the Atomic according to what the instructions said. Thanks for the information by the way, I thought I was doing something completely wrong and was assuming that the MSD Atomic had to be set to performance, or other things in order to keep warranty and for the engine to behave properly. So it was kinda throwing me for a loop compared to what I was expecting, what I thought was right, and how it was behaving, still a bit new to all this.

    In order to allow the Atomic to control timing there are a few requirements.

    • The distributor must connect to one of the input connections on the throttle body (white wire or green/violet wire cable).
    • The vacuum and centrifugal advance must be locked out in the distributor.
    • An adjustable rotor must be installed in the distributor.
    • The yellow wire of the throttle body must be connected to the white wire of the MSD Ignition box.

    Your description above says the distributor is connected to the MSD Ignition box, and we do not offer an adjustable rotor for the HEI distributor.

    Please verify that the installation is set up correctly to allow the Atomic to control timing.

  3. #23

    Default Looking for Help with Atomic EFI settings

    The car definitely sounds much better on that mild setting.

    On the distributor, I was eluding to the fact that that there must be an adjustable rotor, but how was this done on an HEI distributor by your mechanic? If the phasing is off on the rotor, it can cause kick-back or misfiring under different load locations.

  4. #24

    Default Looking for Help with Atomic EFI settings

    That might explain some of the issues and why I keep feeling like the timing isn't quite right. I know that all the wiring was done as explained and the vacuum advance was locked out as you stated, but as for the adjustable part. I don't think that was done, all I know is it was wired according to the instructions and the lockout stuff was done, aside from that, I have no clue. I'll have to check with my mechanic how he did it, really starting to question the quality of the workmanship done. The only other solution is I'm assuming an MSD Distributor. Not fully sure to be honest. I also noticed that even with the timing set to 14 as suggested and all the AFR settings, once the engine is at operating temp, I was tweaking some settings and saw that the engine/Atomic was holding timing at 4 to 5 degrees, is this normal? And if there was no adjustable part put in, could that cause issues? Better yet, is it possible to put an adjustable rotor in a HEI distributor? I honestly have no clue.

    Thanks for the part numbers on the extension cables, going to go look up the price of them.

  5. #25

    Default Looking for Help with Atomic EFI settings

    Just got off the phone with the mechanic and as far as I can understand, all they did was take out something from the distributor, locked out the vacuum advance, and wired it up, it's unknown just how they wired it up (I'm assuming they followed the instructions directed with the Atomic/6AL combo setup in the installation manual) or if the HEI distributor came with an adjustable rotor already. As far as they said, all the distributor is being used for is spark, and that is it. They said the timing is being picked up off the cam sensor, really no idea.

  6. #26

    Default Looking for Help with Atomic EFI settings


    Unfortunately it looks like it's up to you to see how the mechanic wired everything in.

    Start with the distributor, our instructions show that the 4-pin HEI module must be removed to install an installation harness on the magnetic pick-up. This harness then comes out and connects to either the Atomic throttle body or MSD ignition box (depending on which diagram was followed).

    Please trace everything and draw it out for reference.

  7. #27

    Default Looking for Help with Atomic EFI settings

    Will do, thanks for the information, if everything is wired up though correctly, but there is no adjustable rotor, I'm assuming that would be a bad thing?

  8. #28

    Default Looking for Help with Atomic EFI settings

    Yes - that is a problem. The adjustable rotor allows for proper adjustment of rotor phasing. Because the actual spark timing (computed by the Atomic TBI) varies relative to the distributor trigger signal, the position of the rotor tip (when the coil fires) can move relative to the cap terminal. If the rotor is not properly re-phased to accomodate for this, the resulting problems can include crossfire and the generation of RFI (Radio Frequency Interference) as the spark has to jump an unusually large distance from rotor tip to cap terminal.

    Unfortunately, your HEI does not allow for the installation of an adjustable rotor.

    In order to capitalize on the benefits of an adjustable rotor, you'll need a different distributor (such as the MSD 85551) and the adjustable rotor itself (MSD 84211).

    Should you choose to do away with your HEI distributor, you will also need a coil since your existing coil is contained within the cap assembly. Coils to consider are the can-style Blaster 3 (PN 8223), the high-efficiency Blaster SS (PN 8207), or the top-of-the-line Blaster HVCII (PN 8253).

  9. #29

    Default Looking for Help with Atomic EFI settings

    Turns out they wired yellow to the 6AL and purple/green to the distributor. They disconnected the vacuum advance, but I'm here now and found out they didn't lock out the centrifugal mechanical advance. This may be where all my problems are coming from. Not to mention that I noticed the spark is firing off hard from the corner of the distributor rotor, it's leaving burn marks on the corner of each terminal on the cap. I keep telling the mechanic to leave the writing as is, hook up the vacuum advance, and I'll turn off timing control on the atomic. He's being stubborn and seems certain there's no problem and everything is going to line up fine without an issue.

  10. #30

    Default Looking for Help with Atomic EFI settings

    Failure to lock out the existing centrifugal advance mechanism is only one of the issues. The TBI requires stable reference timing - the 15° base timing called for in the instructions. The only way it can compute accurate ignition timing values is if the 15° base timing has been set properly. By leaving the OEM centrifugal advance in the mix, now the values the TBI computes are essentially meaningless - because the reference signal is always moving.

    Secondly, as you noted with regard to the rotor tip and burn marks in the cap - the rotor phasing is not correct. The burn marks indicate that the rotor tip is not properly aligned with the cap terminal at the time of firing. This is also bad because of all the RFI it produces, and you're wasting a bunch of spark energy jumping a huge gap.

    Lastly, if the module was removed from the distributor, along with the 3-wire harness that goes from the module to the cap, there's a good chance that arcing is also occuring under the coil cover. MSD's HEI coil is what is known as an "Isolated Secondary" design - in that proper operation requires that the negative side of the high-voltage winding needs to be grounded. In its nominal configuration, it gets this ground through the 3-wire pigtail that plugs into the module. If the 3-wire pigtail has been removed, there's a good chance the coil secondary winding is finding ground by jumping over to one of the coil primary leads coming from the MSD box. You can check this by removing the coil cover and looking to see if there is evidence of arcing in the area where the original B+ and Tach terminals are located.

    Bottom line - to properly run the Atomic TBI with timing enabled - you will need to change distributors, have an adjustable rotor installed, and add a stand-alone ignition coil.

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