![]() FYI: Holley EFI now sells their own Dual Sync (LINK) & HyperSpark (LINK) Hall-Effect distributors. They're a small cap design, "plug & play" with Holley EFI, and no need for a modified Firing Order. The Dual Sync crank & cam sensor signals also provide sequential injection capability (MPFI applications). The Dual Sync is "plug & play" (into the 10-pin ignition connector on the EFI Main Harness), and both distributors require a CD ignition box (Instructions), unless the Dual Sync is used with a CNP ignition system. 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) https://www.youtube.com/watch?v=2JpHlS1ymBc (Holley EFI HyperSpark Distributor - YouTube Tech Video) A Dual Sync blank cap is available, if the user decides to convert to Coil-Near-Plug/DIS later (no CDI box). Of course, the Dual Sync distributor 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" (← Holley Dual Sync Distributor) Sensor Type .............. ― "Digital Falling" Inductive Delay .......... ― "100.0 usec" (← Synchronization info, adjusted per application.) Ignition Reference Angle ― "50°" (← Inherent Ignition Reference Angle & 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 Fixed Duty Cycle (MSD)" (← MSD CD Ignition Box) ----------------------------------------------------------- Holley CNP Smart Coils and/or GM LSx Ignition Coils (no CD ignition box required): Output Setup Type ..... ― "DIS Coil On Plug" (← Holley CNP Smart Coils and/or LSx Ignition Coils) Dwell Time ................ ― "3.5-5.0 msec" (← See page 1 for Holley CNP coils, and page 3 for GM LSx coils.) https://www.holley.com/brands/holley...efi_dual_sync/ (Holley EFI Dual Sync Distributors) The Custom Ignition Parameters (in System Parameters) for the Holley EFI HyperSpark Distributor: Ignition Type ............. ― "Custom" Crank Sensor Type ..... ― "1 Pulse/Fire" (← Holley HyperSpark Distributor) Sensor Type .............. ― "Digital Rising" (← I prefer Digital Falling, LINK.) Inductive Delay .......... ― "100.0 usec" (← Synchronization info, adjusted per application.) Ignition Reference Angle ― "57.5°" (← Inherent Ignition Reference Angle & rotor-phasing of this unit.) Cam Sensor Type ........ ― "Not Used" (← This distributor doesn't have a cam sensor.) Output Setup Type ..... ― "Points Output Fixed Duty Cycle (MSD)" (← MSD CD Ignition Box) https://www.holley.com/brands/holley..._distributors/ (Holley EFI HyperSpark Distributors) https://www.holley.com/products/fuel.../parts/558-323 (Holley EFI HyperSpark Ignition Adapter) |
![]() Crank & Cam Sensor Wiring Tips: The 10-pin Ignition Connector has one "Chassis Ground" (loose black wire ground) and two "IPU Grounds" (clean ECU ground). Don't use "Chassis Ground" to ground an ignition module (or crank & cam sensors). It's quick & easy to move the ignition module ground wire from (cavity) pin D "Chassis Ground" to pin C or G "IPU Ground", where it should be. If you don't have the actual Metri-Pack terminal release tool, a "safety pin" will work. It just needs to be a stiff wire between .030"-.035" in diameter to release the terminal tab. Then reopen (bend) the terminal tab before reinsertion, so it will clip (lock) into the cavity. http://www.whiteproducts.com/removal_tools.shtml (T-6 Micro Terminal Release Pick Tool) Also, don't use (cavity) pin E "Switched +12V" from the 10-pin Ignition Connector, to power an ignition module (or crank & cam sensors), unless you've modified the wiring source to connect from pin B20 - EST 12V Output (P1B ECU Connector). This LINK explains why & how to do it. http://documents.holley.com/techlibr...10555rev17.pdf (Holley EFI Wiring Manual, Sections 2.1 "Pin-Outs" & 13.0 "Wiring Appendix") |
• Holley 558-313 Ignition Adapter Harness for FAST Dual Sync Distributors:
http://documents.holley.com/199r10687rev2.pdf (FAST Ignition Adapter Instructions)
The FAST Dual Sync distributor harness connects to the Holley EFI 10-pin ignition harness connector.
• A CD ignition box must be used because the FAST Dual Sync distributor only outputs crank & cam signals. (No ignition coil driver.)
This means the loose white "Points Output" wire (Holley EFI main harness) is utilized to trigger the CD ignition box, which fires the coil.
See figure 11 wiring diagram, on page 20 of the Holley EFI Wiring Manual:
http://documents.holley.com/techlibr...10555rev17.pdf (Holley EFI Wiring Manual)
• If a custom shielded cable is used (for whatever reason - not necessary), the "drain wire" is only supposed to be grounded at one end.
1) Holley ECUs already have the shield (drain) wire connection/pin grounded inside, so don't ground it at the sensor end.
2) The ECU already has the pull-up resistor for sinking output (open collector) sensors inside, so don't add anything.
http://www.newark.com/pdfs/techartic...haWire/USC.pdf (Shielded Wiring - look for "drain wire" on page 2 & 3.)
Think of the shield wire as an antenna pointing to the sensor; it's only supposed to be grounded at the ECU end.
• Holley EFI ten cavity ignition harness connections:
Pin "E" provides +12V to both crank & cam sensors.
Pin "C" or "D" provides ground to both crank & cam sensors.
Pin "B" is the cam sensor's signal input.
Pin "A" is the crank sensor's signal input.
See figure 11 & 12 - page 20 & 21 (Hall-Effect) of the Holley EFI Wiring Manual:
http://documents.holley.com/techlibr...10555rev17.pdf (Holley EFI Wiring Manual)
• The Custom Ignition Parameters (in System Parameters) of the FAST Dual Sync distributor:
Ignition Type ............. ― "Custom"
Crank Sensor Type ..... ― "1 Pulse/Fire"
Sensor Type .............. ― "Digital Rising"
Inductive Delay .......... ― "adjusted per application" (← Synchronization info.)
Ignition Reference Angle ― "50°" (← Inherent rotor-phasing of this unit.)
Cam Sensor Type ........ ― "Single Pulse"
Sensor Type .............. ― "Digital Rising"
Output Setup Type ..... ― "Points Output"
Dwell Time ................. ― "2.0 msec" (← Do not set this to 1.5 msec!)
Originally posted by Excerpt from Holley 558-313 Instructions
Originally posted by Holley EFI Tech Department

https://www.fuelairspark.com/distrib...tributors.html (FAST Dual Sync Distributors)
https://www.fuelairspark.com/ignitio...omponents.html (Replacement Parts)
http://www.summitracing.com/search/b...s?autoview=SKU (Summit Racing)
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