Question about phasing AMC/Duraspark distributor for Holley EFI

Discussion in 'Injection Tech' started by acct21, Nov 26, 2018.


  1. acct21

    acct21 Farmall Cub

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    Bill,

    Saw your recent post over on FSJNetwork.com, as well as your generous offer to answer questions over on this forum.

    Have searched the Injector Tech forum and the FAQs. Under the 'Start Here' have found the detailed write up for phasing the AMC Motorcraft/Duraspark for TBI -- but you say the Holley system has "different phasing requirements?" I have not been successful locating that information.

    I have a Holley Sniper on my AMC 360, and would like to convert to timing control through the Sniper. Can you touch on the differences required to phase the Motorcraft/Duraspark distributor for use with the Holley system -- or perhaps point to the link? Thanks in advance.
     
    Last edited: Nov 26, 2018
  2. Bill USN-1

    Bill USN-1 Moderator Staff Member Moderator

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    Distributor phasing mods are the same.
    The amount of Phasing is listed in the manual.
    http://www.binderplanet.com/forums/index.php?threads/amc-distributor-set-up.114498/

    MAGNETIC PICKUP DISTRBUTOR
    From the manual:
    Before beginning, please know the following: You will need to lock out the advance on the distributor if it is not already done. You will need an adjustable rotor (available from MSD.) You will need a timing light. You will need a mark on the balancer at 15 degrees before top dead center (BTDC). If your balancer is not already marked, please follow step one in the distributor removal section to create a mark on your balancer using a paint pen. Overview: Sniper EFI can control timing using most common magnetic pickup distributors currently available (ex. MSD). However, you may need to make several very simple changes to the distributor which are outlined in the following section. It is very important that you “lock out” the advance built in to the distributor and install an adjustable rotor. Not “locking out” the distributor and installing an adjustable rotor as outlined in these instructions can cause the engine to run poorly or even cause engine damage. NOTE: These instructions are directed toward MSD distributor installations. However, the same basic things need to be done with any magnetic pickup distributor before being used with Sniper EFI.

    You do not need an adjustable rotor.


    THERE'S A COUPLE THINGS YOU WILL NEED.
    First you will need to download the manual if you don't have it.
    It is much more in depth then the starters guide.
    In it, it specifies the phasing requirements for timing control and the additional parts required to make it work.
    This is something most don't understand when buying the "cheap" fuel only systems.
    It's only cheaper because it doesn't include everything you need for a complete system.

    https://documents.holley.com/techlibrary_199r11321.pdf
    https://documents.holley.com/techlibrary_199r11031r-1.pdf

    Coil Driver
    https://documents.holley.com/199r10387.pdf

    Once you have the manual, phasing is normally around pg 25.
    Once that is done, you will need to complete the timing control set up around pg 47

    The polarity of the signal from the pickup is important so you will need to follow the directions to determine the correct orientation of the ppl and org wire connections.
    Normally, ppl is pos and org is neg.
     
    Last edited: Nov 26, 2018
  3. acct21

    acct21 Farmall Cub

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    Thanks for the information.

    I bought the Sniper with the full knowledge that it was incomplete. Though it runs well without timing control, I had hoped to eventually use the Motorcraft distributor to allow the Sniper to control the timing. I had an extra distributor on hand, and have already locked out the mechanical advance (and deleted the vacuum advance) following the instructions you provided.

    My confusion came from the comment you posted in the Jeep forum about the Holley requiring "different phasing." From review of the Holley Sniper manual (admittedly for the MSD distributor), it looks as if Holley is calling for the the rotor to be phased 15° (retarded) from the stock reluctor position. This appears to be approximately what you call for on the GM TBI conversions, so I have gone ahead and modified my unit to mirror these instructions. I've made sure the rotor tip is at the trailing edge of the spark tower electrode (headed to the #8 tower), so this should give the ECU enough room to work with when adding in timing.

    I'm already running an MSD 6AL CD box with the adapter harness for the Motorcraft distributor. Switching over to ECU timing control will require unplugging the distributor from the CD box, attaching it to the ECU harness (which has matching wire colors and plugs to ensure the correct polarity), and attaching the white points wire from the ECU to the white points wire on the CD box.

    I've verified the calibration procedures with Holley tech support, and will now sync the base timing with the ECU -- and hopefully it will take it from there.
     
  4. acct21

    acct21 Farmall Cub

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    In this position, the advance plate and upper distributor shaft are completely locked (no movement), and the vane/fin of the reluctor is perfectly aligned with the pickup.


    [​IMG]
     
  5. Bill USN-1

    Bill USN-1 Moderator Staff Member Moderator

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    Setting up the distr like the GM is not enough retard.
    You need to install the distr and set the timing acording to the instructions, then set the phasing.
    I think you will find it will change quite a bit.
     
  6. Tom Ledkins

    Tom Ledkins Farmall Cub

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    Just curious did this get resolved?
     
  7. Bill USN-1

    Bill USN-1 Moderator Staff Member Moderator

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    By resolved, I provided all the information he needed to properly phase his distr for the Holley sniper system.
    So yes, it was resolved.
     
  8. Tom Ledkins

    Tom Ledkins Farmall Cub

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    Ok I have to ask. The instructions for the sniper system say to put the #8 cylinder in the case of the IH 15 degrees retarded (before top dead center) and install the distributor with the rotor adjusted to 15 degrees retarded. So for our purposes this means with the #8 cylinder 15 BTDC install the distributor with the rotor pointed and centered at the #8 position on the distributor cap and then line up the reluctor? Is this correct? Holley has a video on phasing but it is a completely different procedure. Sorry for the questions but as usual nothing in any instructions apply to the scout. Also as far as I can tell the timing at wide open throttle is 32 degrees.
     
  9. Bill USN-1

    Bill USN-1 Moderator Staff Member Moderator

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    Retarded is ATDC not BTDC.
    So you are passing 0* going clock wise just as is shown and explained in my distr FAQs.
    It comes down to how many degrees the system requires the phasing to be.
    It doesn't matter if it's a chevy or AMC on cyl 1 or an IH on cyl 8.
    it's all the same procedure.
     
  10. Tom Ledkins

    Tom Ledkins Farmall Cub

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    OK so I get phasing. So after that the Holley instructions say to install the distributor at 15 Degrees BTDC with the rotor point at the #8 cylinder so I assume I do that since that is what holley wants instead at ) degrees since that is what the IH would normally be timed at. Again sorry for the questions I did have this scout running on a TBI setup but do to various reasons I wanted to give the holley sniper setup a try.
     
  11. Bill USN-1

    Bill USN-1 Moderator Staff Member Moderator

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    Did you watch the video linked in the manual listed above.
    It discusses the entire procedure.
    The 15* isn't really important at the beginning.
    You'll be changing it to 45* once you stab it.
    So you can just pick TDC #8 or 15* #8 and then follow from there.
     
  12. Tom Ledkins

    Tom Ledkins Farmall Cub

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    Yes I have watched the video and maybe its just the terminology used. In the video he clearly lines the reluctor and pickup up with the balancer at 45 degrees and then rotates to 30 degrees and lines up the rotor. I should be able to just do this in reverse and achieve the same thing. I guess for me the confusion on the terminology is he is using 45 and 30 degress before the #1 cylinder is at 0 degress on a clockwise motor not after. Again I am just trying to wrap my head around it and I am probably just making it harder than it needs to be.
     
  13. Bill USN-1

    Bill USN-1 Moderator Staff Member Moderator

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    Note: a V8 has 90* of timing between each cap terminal.
    45* of physical degrees.
    360/8= 45

    Yes he sets the crank at 45*BTDC.(reluctor centered on the pickup)
    Then locks the distr housing down.
    Then because it's a street engine and is likely to have ~30* of timing, He moves the crank 15*(1/2 of 30*) so the crank is now at 30*BTDC
    Then you phase the rotor to be centered on the cap terminal, without moving the distr or the engine.

    Now, without having an adjustable rotor, you can't do this.
    So you will need to use the reluctor adjustment to do the same thing.
    Just work it backwards.
    Set the rotor centered on the cap with the engine at 30*.
    Then rotate the engine back to 45* and set the reluctor.

    then you can verify the settings by walking back through it the other direction.

    Once done, you need to perform the distr/timing setup to verify the computer is in sync with the distr and the timing doesn't change during rpm changes unless timing control is enabled.
     
  14. Tom Ledkins

    Tom Ledkins Farmall Cub

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    Thats what I did and only a few things to button up and I can get it started. Unfortunately when dealing with an IH nothing can be easy I am just trying to make sure I can get it done without to much trouble. Thank you for the help.
     
  15. Bill USN-1

    Bill USN-1 Moderator Staff Member Moderator

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    I haven't heard any of my customers say they have had problems figuring out the timing on an IH or any other engine!
    Set distr at 0* connect and turn key.
     
  16. Tom Ledkins

    Tom Ledkins Farmall Cub

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    Yes thats true, want I meant was when installing anything non standard like fuel injection or many after market accessories that weren't designed for a scout. They will work you just have to sometimes adapt them
     
  17. Tom Ledkins

    Tom Ledkins Farmall Cub

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    Thanks for the help got it started today without much trouble now to drive it and see how well it self tunes.
     

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