Yet another Dual Sync failure.

[Bill C]

Here's what MSD came up with for the bad Dual Sync distributor and quoted a repair price of $198:
565-200 FAILED TESTS
REPLACED:
MODULE
BEARINGS
OIL SEAL
CAP
ROTOR.

Nobody has any thoughts on the setup question asked before this post?

Why would an almost new distributor need bearings and oil seal? Or cap & rotor for that matter? I do understand that if they replace everything less chance of it coming back, but that begs the question of initial parts quality being used. Sounds like padding the bill to recover time/money from what should be a defective product repair. That is, unless you have put 75,000 miles on it and driven it through Winter, Spring, Summer & Fall. Come on Holley/MSD step up your game.

[Danny Cabral]

Originally Posted by Danny Cabral 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) For naturally aspirated engines, the rotor is usually phased halfway between minimum & maximum amount of timing advance used. For forced induction engines, the rotor is usually phased at maximum boost retard, because that's when cylinder pressure is the greatest. Testing the MSD CD ignition box. Points Output - white wire & Magnetic Pickup - violet/green triggering: https://www.msdperformance.com/suppo...ng_techniques/ (Troubleshooting Info)

[a b c]

If it were mine, I'd verify the digital Reference Angle puts the physical location of the rotor in the proper position for my application.

[Danny Cabral]

You're welcome.

[jft69z]

It all appears to be good. As always, thanks for your help!

[Danny Cabral]

If the timing is synchronized at idle and higher RPM, you're good to go.
https://forums.holley.com/showthread...087#post255087 (Ignition Timing Synchronization - A Two Step Process)

[jft69z]

So I checked it this morning. I must have adjusted the Reference Angle to 0° at the time.

I reset it this morning to 10°, turned off Idle Spark control, Static Timing Set test to 20° and rotated the distributor to match 20°. Then ran it up to around 3000 RPM and noticed the timing slowly retard to about 15°. Shut it off, changed the Inductive Delay from the default 1.0 usec to 20 usec. Tried it out, seemed good, so changed it back to 10 usec, still seems good. Set it down to 5 usec and it seemed to drift a little, so set it back to 10 usec. Re-enable the Idle Spark control, etc., and left it. Does that seem reasonable to you guys?

[jft69z]

Thanks Danny & ABC. I initially set the timing mark at 10° on the balancer, and set the rotor at the # 1 pin on the distributor cap when installing the distributor (sort of like the procedure the dual sync had you do, but at 50° with that setup).

First, I did a timing light check with the fuel pump off, to check crank timing at 15° (all good). Next, did verify actual timing with a light (set Static Timing to 20°, Idle Spark control - OFF), and ran it up to around 3000 RPM to check for drift. Timing seemed stable, so I left the Inductive Delay where it was. Also checked it at various spots with the Static Timing Set back to normal, and it seems to track commanded vs. actual timing. As mentioned earlier, I did tweak the numbers a little bit, but will double check them to make sure Reference Angle is set to 10°.

I looked at the entire thread you posted real quick Danny, and I'll dig into it much deeper in a bit. Lot of good info in there. Thanks again!

[a b c]

To verify the Reference Angle is acceptable, since you are still dealing with a mechanical air gap system (distributor), I'd set the timing as usual (start with a commanded value of 30°), verify commanded matches actual while at 2500 RPM or so, if not make it do so. Shut the engine off, turn the crank to your verified point of 30°. Remove the distributor cap and see how the rotor lines up with the number one pin. If the rotor is near the middle of the pin, your good to go, if not, start making Reference Angle adjustments until it does while repeating the timing set process.

[Danny Cabral]

Are you suggesting the HyperSpark settings are also good for this distributor as well?

No, the Ignition Reference Angle for the GM HEI distributor is 10°. The Inductive Delay is always adjusted the same way (← synchronization info, adjusted per application).

[jft69z]

Thanks Danny. The distributor I ended up with isn't a HyperSpark though. I have the HEI small cap, which also appears to have a setting in the V5 EFI software called "GM HEI (Computer Controlled)". Also got the adapter harness 558-304 to mate it with the Dominator ECU (Terminator Stealth with transmission control system).

Are you suggesting the HyperSpark settings are also good for this distributor as well?
https://www.holley.com/products/ignition/distributors/chevrolet/parts/8366
https://www.holley.com/products/fuel_systems/fuel_injection/hp_efi/hp_harnesses/parts/558-304

[Danny Cabral]

Originally Posted by Danny Cabral 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)

[jft69z]

Here's what MSD came up with for the bad Dual Sync distributor and quoted a repair price of $198:
565-200 FAILED TESTS
REPLACED:
MODULE
BEARINGS
OIL SEAL
CAP
ROTOR.

Nobody has any thoughts on the setup question asked before this post?

[jft69z]

So the new, small cap HEI distributor is installed, along with the adapter harness and associated rewire. Runs good as expected, but have a question about setting it up.

So with the Dual Sync, they have you set the harmonic balancer timing mark at 50°, and the EFI software uses 50° as a Reference Angle value. Checks with a timing light show actual reflects commanded timing, all good.

With the HEI - 'computer controlled' (as the EFI software calls it) option checked to reflect the new distributor, it has a 10° Reference Angle already set & 1.0 usec Inductive Delay.

What's the preferred method here? Set balancer timing mark to 10°, line up rotor on distributor cap at # 1 cylinder and go with it? I checked it with a timing light, and with a Static Timing value programmed, and it was off by a fair amount. Setting the EFI software Reference Angle to zero, and checking it again made it closer. I rotated the distributor a bit to get it lined up with commanded value & left it there.

I'm guessing that as long as the commanded vs. actual timing is the same, any method will work? The distributor instructions were absolutely no help, they just say use the factory procedure/emission label as a reference. Holley & MSD documentation is no help either.

Not much help on a 1972 Monte Carlo, with a big block 454. Looking in GM ESC for a '88 GMC truck (something that this type of distributor would've been used in), the factory just says unplug the 'SET TIMING' connector and adjust to spec. Again, no such option on the '72. Any thoughts or suggestions would be appreciated.

[jft69z]

I was looking at your threads too during my research, that was a big help too.

I was literally just going to pickup the phone and make some calls, LOL. I already printed out MSD's number yesterday as I think you mentioned it in the other thread. Thank you!

EDIT: Just called them, gave me an RMA number and said maybe a 2-3 week lead time for repairs. No circuit boards available as a field service item at this time, for us to repair them ourselves.