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Thread: Holley Sniper EFI Timing Control Question

  1. #1

    Default Holley Sniper EFI Timing Control Question

    Hey guys, I'm considering purchasing a Sniper Kit for my '86 C10 with a 350 that I'm building. I definitely want to use the timing control feature, and I'm trying to get the truck setup for it before I make the purchase. I already have an MSD 85551 distributor, which is currently locked out, and I have an adjustable rotor 84211 on the way. Reading through the instructions posted online for the Sniper Kit on how to setup the distributor, I'm a little confused on how it's supposed to work. The instructions for the Holley Dual-sync distributor make sense, but the instructions for the MSD distributor don't.

    As I understand it, the way the timing control feature works, is that you set the distributor (more specifically, the Hall-Effect sensor/pickup coil) to more advance than the engine will ever see (listed as 50° BTDC for the dual sync), and the EFI will interrupt the signal from the Hall-Effect sensor going to the coil and delay it as needed to achieve a lower advance spec. The EFI system technically can only "take away" advance, not add to it. When I read into the MSD distributor setup section, it says to only set the distributor back to 15° BTDC. This does not make sense to me, as my engine should require 34°-36° total timing. How will the EFI system add advance to 34° if the pickup coil only gives it a signal 15° before it's supposed to fire? Is this procedure correct as listed in the Holley instructions, or should I actually be setting my Hall-Effect at 50° BTDC, and my rotor phasing at 30° BTDC as I seem to be finding elsewhere online?

  2. #2
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    https://www.youtube.com/watch?v=AM7r-DauCak (Holley EFI Dual Sync Distributor - YouTube Tech Video)
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  3. #3

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    While that video is very informative, I do not have a Dual Sync distributor, I have an MSD distributor. I'm still not sure if my MSD distributor is supposed to follow the same steps. I don't understand why in the Holley instructions the Dual Sync would require a setting of 50° BTDC, and the MSD would only require 15° BTDC?

  4. #4
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    Quote Originally Posted by Nick_R_23 View Post
    While that video is very informative, I do not have a Dual Sync distributor, I have an MSD distributor.
    Oops, sorry. Your post was long, and I didn't read it thoroughly.

    I'm still not sure if my MSD distributor is supposed to follow the same steps.
    With EFI, you don't follow the MSD installation instructions. Follow the Holley Sniper EFI instructions.
    http://documents.holley.com/199r11031r.pdf (Holley Sniper EFI Instruction Manual - For my own reference.)
    http://documents.holley.com/199r11193.pdf (Holley Sniper EFI Quick Start Manual - For my own reference.)

    I don't understand why in the Holley instructions the Dual Sync would require a setting of 50° BTDC, and the MSD would only require 15° BTDC?
    The ECU needs an Ignition Reference Angle, so it can control the timing. It's the amount of timing advance available to the ECU. The Ignition Reference Angle needs to be at least 10° higher than the maximum amount of timing used in the Base Timing Table. 60° Ignition Reference Angle allows up to 50° of ignition timing. 50° Ignition Reference Angle allows up to 40° of ignition timing. 60° & 50° are common Ignition Reference Angles.
    http://www.masterenginetuner.com/top...all-fails.html (Crank Reference Angle Importance)

    The base ignition timing needs to be synchronized (laptop/TSLCD & timing light) by slightly moving the crank sensor or distributor. You don't "adjust" the Ignition Reference Angle per se, without also adjusting the crank sensor. It is "set" (synchronized) with the crank sensor or distributor. The only parameter that should be "adjusted", is the Inductive Delay, which synchronizes the timing at higher RPM. Use your timing light and believe it above all else; it's always the real timing (which should match what the laptop/TSLCD indicates).
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  5. #5

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    Quote Originally Posted by Danny Cabral View Post
    Oops, sorry. Your post was long, and I didn't read it thoroughly.

    The ECU needs an Ignition Reference Angle, so it can control the timing. It's the amount of timing advance available to the ECU. The Ignition Reference Angle needs to be at least 10° higher than the maximum amount of timing used in the Base Timing Table. 60° Ignition Reference Angle allows up to 50° of ignition timing. 50° Ignition Reference Angle allows up to 40° of ignition timing. 60° & 50° are common Ignition Reference Angles.
    http://www.masterenginetuner.com/top...all-fails.html (Crank Reference Angle Importance)

    The base ignition timing needs to be synchronized (laptop/TSLCD & timing light) by slightly moving the crank sensor or distributor. You don't "adjust" the Ignition Reference Angle per se, without also adjusting the crank sensor. It is "set" (synchronized) with the crank sensor or distributor. The only parameter that should be "adjusted", is the Inductive Delay, which synchronizes the timing at higher RPM. Use your timing light and believe it above all else; it's always the real timing (which should match what the laptop indicates).
    No worries, it's late here too, LOL.

    I guess the part I'm not understanding is where my Ignition Reference Angle is coming from with the MSD distributor. I fully understand that the ECU needs to see advance in order to allow for a certain degree range of timing, and this is the 50° as stated with the Dual Sync. However, here are the steps pulled directly from the Holley Sniper EFI Instruction Manual, on page 17:
    INSTALL THE ADJUSTABLE ROTOR
    1. Install the adjustable rotor MSD PN 84211 or PN 8421 on to the distributor shaft (See note below for applications)
    2. Set the phasing of the adjustable rotor by putting it retarded (opposite of distributor rotation) 15° on the rotor indicator. See Pictures for reference.
    And
    INSTALL THE DISTRIBUTOR
    1. Rotate the crankshaft in the direction of engine rotation until it reads 15° before top dead center (BTDC) on the compression stroke if it is not already there.

    6. At this time you should test fit the distributor cap ensuring that the #1 cylinder terminal aligns with the rotor. You should move the body of the distributor to correct for any misalignment at this time.
    Correct me if I'm wrong on this, but per Holley's instructions as listed above, using an MSD distributor, the crankshaft needs to be retarded to 15° BTDC, and the distributor cap needs to also be retarded to 15° BTDC. This would give me a 30° Ignition Reference Angle, would it not? But then the instructions also state to make sure that the rotor lines up with the #1 terminal on the distributor cap...thus eliminating the 15° I just put into my rotor, and bringing my IRA back down to only 15°, which given your stated 10° window, would only allow my ECU 5° BTDC of timing control?

    There must be something I'm not seeing here, as since my engine wants 34° total timing, given your 10° window I would need at least a 44° Ignition Reference Angle, or more commonly 50° as you stated. I don't see how Holley's instructions will achieve this.

    EDIT: The way I was taught to set IRA seems very similar to the instructions for the Dual Sync. I was told that I should rotate the crankshaft to 50° BTDC on the compression stroke, as this is what I would want my IRA to be. Then, I'd drop the distributor in and align one of the reluctor wheel teeth with the Hall-Effect sensor, and tighten the distributor body down. This would set my Ignition Reference Angle. Then, I would rotate the crankshaft to 30° BTDC, and align the adjustable rotor exactly in line with the #1 terminal on the cap. This ensures my rotor is within a few degrees sweep of that terminal no matter how much timing is needed. I would have assumed that this procedure would also be correct for the MSD distributor, but Holley seems to think otherwise? Or will this setting work as well?
    Last edited by Nick_R_23; 11-09-2016 at 03:33 AM.

  6. #6
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    There is an ignition "Reference Angle" parameter on the Sniper 3.5" LCD Touchscreen unit.
    The Ignition Reference Angle needs to be at least 10° higher than the maximum amount of timing used.
    I think the Sniper EFI ECU has an inherent Ignition Reference Angle setting of 50°, for MSD Magnetic & Holley Dual Sync distributors.
    http://documents.holley.com/199r11031r.pdf (Holley Sniper EFI Instruction Manual - Ignition Setup, Page 27)
    http://documents.holley.com/199r11193.pdf (Holley Sniper EFI Quick Start Manual - Step 8, 9 & 10, Page 9)

    TIP: If you're unsure about the initial distributor installation/positioning, or you'd like to verify the base timing before
    starting the engine
    , it's suggested to temporarily disconnect the fuel injector harness, and crank the engine while viewing
    the Cranking Timing with a timing light. This prevents the engine from starting, but still allows you to adjust & confirm the
    base timing (engine safety). When the Cranking Timing is correct (synchronized), the timing at idle will be too.
    If you're cranking the engine (with the injector harness disconnected), sync at 15° or whatever your Cranking Timing is.
    If you're idling the engine (without disconnecting anything), sync at 25° or whatever your idle timing on your Timing Table is.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  7. #7

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    Quote Originally Posted by Danny Cabral View Post
    There is an Ignition Reference Angle parameter on the Sniper 3.5" LCD Touchscreen unit.
    The Ignition Reference Angle needs to be at least 10° higher than the maximum amount of timing used.
    I think the Sniper EFI ECU has an inherent Ignition Reference Angle setting of 50°, for MSD Magnetic & Holley Dual Sync distributors.
    http://documents.holley.com/199r11031r.pdf (Holley Sniper EFI Instruction Manual - Ignition Setup, Page 27)
    http://documents.holley.com/199r11193.pdf (Holley Sniper EFI Quick Start Manual - Step 8, 9 & 10, Page 9)
    I'm not sure if the parameter is there or not. I don't physically own the unit yet, just trying to get setup for it, so it's as bolt on as possible when I do purchase it. I would assume that you are correct about the 50° inherent setting, as apparently it looks for that 50° Ignition Reference Angle with the Holley EFI Dual Sync distributor, so I don't see why it wouldn't with the MSD.

  8. #8
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    Quote Originally Posted by Nick_R_23 View Post
    I'm not sure if the parameter is there or not. I don't physically own the unit yet, just trying to get setup for it, so it's as bolt on as possible when I do purchase it. I would assume that you are correct about the 50° inherent setting, as apparently it looks for that 50° Ignition Reference Angle with the Holley EFI Dual Sync distributor, so I don't see why it wouldn't with the MSD.
    I'm glad that I'm not alone in my confusion on this topic, and piggybacking your thread, since it should be helpful to us both. I don't understand why, if you already have a "locked out" distributor (but are not using timing control yet), that you cannot simply set it at 15° or whatever you choose, then verify the same spec in the handheld, do the necessary wiring changes to run timing control, and be done?

  9. #9
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    Quote Originally Posted by rel3rd View Post
    I don't understand why, if you already have a "locked out" distributor (but are not using timing control yet), that you cannot simply set it at 15° or whatever you choose, then verify the same spec in the handheld, do the necessary wiring changes to run timing control, and be done?
    I have to agree.
    There is an ignition "Reference Angle" parameter on the Sniper 3.5" LCD Touchscreen unit.
    The Ignition Reference Angle needs to be at least 10° higher than the maximum amount of timing used.
    The Sniper EFI ECU has an inherent Ignition Reference Angle setting of 50°, for MSD Magnetic & Holley Dual Sync distributors.
    So install the distributor with the #1 cylinder at 50° BTDC on the compression stroke, and the rotor pointing to #1 cap terminal.
    Then synchronize the ignition timing (cranking or idling) by turning the distributor, and lock it down. Then check rotor phasing.
    If you're cranking the engine (with the injector harness disconnected), sync at 15° or whatever your Cranking Timing is.
    If you're idling the engine (without disconnecting anything), sync at 25° or whatever your idle timing in your Timing Table is.

    FYI: Just like a carbureted application, if your distributor ends up facing the "wrong" direction (aesthetics), you can
    remove the distributor assembly from the engine and reinstall it in the position you like without turning the inner shaft.
    You can remove the distributor cap and loosely tape the rotor to the distributor body for maintaining the alignment.

    Ensure the distributor's "rotor phasing" is correct:
    http://documents.msdperformance.com/8644_tb.pdf (MSD Rotor Phasing Document)
    MSD has a good video on why it's important:
    http://www.youtube.com/watch?v=aWMlNwGW0tM (MSD Tech - Rotor Phasing Video)
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  10. #10

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    I called Holley's tech support and they could not provide any info for me on running the Sniper EFI with an MSD distributor. They referred me to MSD, and the tech at MSD was a little more helpful. Apparently, MSD also specs the same 15° procedure with their Atomic EFI system. He couldn't completely explain to me how or why this works, but he did assured me that if I set mine up exactly as the instructions stated, that it will work just fine.

    However, I *think* I may have figured this out. My adjustable rotor should be in tomorrow, and if it does show up, I'm going to drop the distributor in and test my theory. It's making my brain hurt trying to visualize it in my head, so I want to actually physically see what is occurring.

    I'm pretty sure this is literally the same procedure, just done in reverse and in a very confusing way. I'm theorizing that if I do their procedure (15° on the rotor, 15° on the crank), and then actually turn the crankshaft to a certain degree BTDC, that the reluctor wheel should line up perfectly with the Hall-Effect sensor in the distributor.

    To start out, in "stock" form, on the locked out distributor, the rotor and reluctor wheel share a relation. When the rotor tip is pointing at the #1 terminal, the reluctor wheel lines up with the Hall-Effect sensor. What they are doing is retarding the rotor 15° in relation to the crankshaft AND the reluctor wheel (rotor tip is sitting 15° counterclockwise in the distributor in relation to #1 terminal). Then, they want you to advance the crankshaft 15° (clockwise), and drop the distributor into place. While this seems like it is "zeroing" out the distributor, if left in place as is, the rotor tip does indeed line up with the #1 terminal on the cap now. HOWEVER, what changes is that the reluctor wheel is no longer lined up with the Hall-Effect sensor. Additionally, if the body of the distributor is held in place and the crankshaft turned counterclockwise, back to 0° TDC, the rotor is now 30° BTDC, as it started out 15° retarded, and now the crank is backed off of the 15° it was set to initially. THIS would be the 30° rotor setting that seems so familiar in the "50° initial/30° phased rotor" specs I keep finding online. Keep in mind that the reluctor wheel is still not in phase with the sensor still. My theory here is that if I backed the crankshaft off until the reluctor now lines up with the Hall-Effect sensor, the timing mark that my balancer will line up with will be at or very close to the 50° ignition reference angle when added to the 30° already in play. The difference now is that the Hall-Effect sensor is so advanced that it is picking up the signal from the reluctor tab normally meant for cylinder #2, thus allowing the ECU to indeed see the reference signal with plenty of time to calculate the the time it needs to send an output signal to the coil!

    EDIT: I'm also theorizing that this angle is built into the Dual Sync distributors, and this is why the procedure is much more straightforward and the Dual Sync does not utilize an adjustable rotor - the factory has already performed these steps for you!
    Last edited by Nick_R_23; 11-11-2016 at 03:03 AM.

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