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Thread: HP with Dual Sync kicks back when starting.

  1. #1

    Default HP with Dual Sync kicks back when starting.

    440 Mopar with Holley Dual Sync Distributor (but running Paired injection - not Sequential). Engine runs well, timing has been verified when running. Customer is using a Holley Dual Sync Distributor, but not using the cam signal. Rotor is phased correctly, yet the engine kicks back at start cold or hot. Any thoughts? Changing the crank timing from 10° to 20° doesn't change anything.

  2. #2
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    Quote Originally Posted by fastmanefi View Post
    Engine runs well, timing has been verified when running. Customer is using a Holley Dual Sync Distributor, but not using the cam signal.
    Why isn't it in Sequential Injection Strategy? It's not the problem, I'm just investigating a possible error pattern. How are the Custom Ignition Parameters programmed?

    FYI: Holley EFI now sells their own Dual Sync Hall-Effect distributors (LINK).
    They're a small cap design, "plug & play" with Holley EFI, and no need for a modified Firing Order.
    The crank & cam sensor signals also provide sequential injection capability (MPFI applications).
    It's "plug & play" (into the 10-pin ignition connector on the EFI Main Harness) and requires a CD
    ignition box (Instructions). The MSD 6201 Digital 6A CDI box & 8253 HVC-2 coil are a great match.
    The MSD CD ignition box is wired as shown in the Holley EFI Wiring Manual:
    http://documents.holley.com/techlibr...10555rev17.pdf (Holley EFI Wiring Manual - Figure 11, Page 20)
    https://www.youtube.com/watch?v=AM7r-DauCak (Holley EFI Dual Sync Distributor - YouTube Tech Video)
    A blank cap (LINK) is available, if the user decides to convert to Coil-Near-Plug/DIS later (no CDI box).
    Of course, this component can also be used as a crank and/or cam sync/oil pump drive unit.

    The Custom Ignition Parameters (in System Parameters) for the Holley EFI Dual Sync Distributor:
    Ignition Type ............. ― "Custom"
    Crank Sensor Type ..... ― "1 Pulse/Fire"
    Sensor Type .............. ― "Digital Falling"
    Inductive Delay .......... ― "100.0 usec" ( Synchronization info, adjusted per application.)
    Ignition Reference Angle ― "50°" ( Inherent rotor-phasing of this unit.)
    Cam Sensor Type ........ ― "Single Pulse" ( "Not Used" for TBI, unless CNP ignition.)
    Sensor Type .............. ― "Digital Falling"
    Output Setup Type ..... ― "Points Output" ( CDI box ground trigger.)
    Dwell Time ................. ― "2.0 msec" ( Do not set this to 1.5 msec!)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  3. #3

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    I questioned if the customer's installer could get the distributor installed correctly. As far as the cam signal was concerned, because with a Mopar the distributor base hits the heads. So you really have to plan the install relative to the CAM LED, in order to find out where to grind the distributor base. I have seen too many distributors that have been ground to death on Mopars. So the Dual Sync distributor is still a good idea, even if you just use the crank. A crank trigger was out of the question for this customer. The tune is set for Paired injection, 1 Pulse/Fire, Digital Falling, 60° Ignition Reference Angle, no cam.

  4. #4
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    Has the Cranking Timing (synchronization) been verified? Is the starter cable AWG large enough? Is the engine block well grounded?
    Also, I don't think 60° of Ignition Reference Angle is acceptable. 50° is supposed to be the inherent rotor-phasing of this distributor.
    https://forums.holley.com/showthread...6402#post76402 (Related Forum Thread)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  5. #5

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    Yes, Cranking Timing has been verified. My next move is to walk him through changing the crank Ignition Reference Angle to 50°, and reset the timing with a timing light.

  6. #6
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    Quote Originally Posted by fastmanefi View Post
    As far as the cam signal was concerned, because with a Mopar the distributor base hits the heads. So you really have to plan the install relative to the CAM LED, in order to find out where to grind the distributor base. I have seen too many distributors that have been ground to death on Mopars. So the Dual Sync distributor is still a good idea, even if you just use the crank.
    This doesn't make sense. Ultimately, a distributor can be repositioned anywhere that fits (rotationally, in gear teeth increments).
    Also, the Holley Dual Sync Distributor doesn't have a specifically designated #1 cap terminal. Any cap terminal can be selected as #1.
    https://www.youtube.com/watch?v=1gI4FDfU2sI (Holley EFI Dual Sync Distributor Installation - YouTube Tech Video, 5:00-5:30 minutes.)

    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.

    Yes, Cranking Timing has been verified. My next move is to walk him through changing the crank Ignition Reference Angle to 50°, and reset the timing with a timing light.
    Does the engine crank over fine with the ignition system temporarily disabled?
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  7. #7

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    I agree, something doesn't make sense. I'll have more info today. It cranks fine with ignition disabled. He replaced the starter with a Powermaster unit and measured the voltage during cranking.

    I'm thinking he might have a bad distributor cap or just maybe, the dual-sync has the rotor phasing off. It's a 565-103 for an RB Mopar big block, CCW distributor rotation. If he sets the engine at 20°-25° (about the middle of the timing range) and pulls off the cap, the rotor is about 1/4" off from the center of the terminal. I wish I was there to see this for myself. Thanks Danny, I'm on it and I'll let the forum know what I find.

    6-24-17 UPDATE: Problem solved. After changing the Ignition Reference Angle to 50°, then rotating the distributor slightly to get the timing to match the "Static Timing" value, everything works with no kick back! So the only real change was changing the crank Ignition Reference Angle from 60° to 50°, and then resyncing the timing. It's possible that the timing was not set correctly when the Ignition Reference Angle was 60° to begin with, because it should have worked with 60° also. I really do not know. Anyway, it's fine now. Thanks Danny.

  8. #8
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    Quote Originally Posted by fastmanefi View Post
    It's possible that the timing was not set correctly when the Ignition Reference Angle was 60° to begin with, because it should have worked with 60° also.
    As I stated in post #4, I don't think 60° of Ignition Reference Angle is acceptable. 50° is supposed to be the inherent rotor-phasing of the Holley Dual Sync distributor.

    Thanks Danny.
    You're welcome.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  9. #9

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    I'll go with it because it works, but 10° at the crank is only a 5° change at the distributor, and I would assume the rotor width would handle that easily. Heck, the rotor slop & backlash is more than that. Oh well.

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