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Thread: Very bizzarre issue: MSD timing retarding 20°.

  1. #1

    Default Very bizarre issue: MSD timing retarding 20°? maybe?

    I have a long 9 page troubleshooting post about this issue on the Holley Sniper EFi page, but I typed a lot and it's filled with lots of troubleshooting that I did in order to get me to this point, so I'll spare you the details, but here's the link to my post if you were curious:
    I was too late in the day today when I made my phone call to MSD today, so I'll try them tomorrow. I'm basically curious if anyone has ever had an experience or phenomenon like what I'm experiencing.

    Short version:
    Can an MSD 6520 Digital 6 box have an internal failure/problem which would cause it to retard ignition timing by exactly 20° at all times?

    Long version with details:
    New Dart 406 engine with Holley Sniper. Built and installed this winter, driven, drag raced, auto crossed, used and ran very very well from March - August 29th at 3pm. Drove the car around town that morning and parked it; came out later to drive it again and it was completely different. Would not start without throttle input, and would bog, stall, hesitate and blow fuel vapor out the Sniper TBI. Many hours of troubleshooting later, I determined it was an ignition issue. The timing is self-retarding itself 20°! I'm certain of it. I spent days checking this. I initially thought it was something weird in the Holley Sniper, but after checking all the settings and using several known-good tune files, I thought maybe it wasn't sniper related. So, today I removed the MSD 85551 distributor, reinstalled the weights & springs, removed the adjustable rotor and replaced it with the normal rotor, and let it control timing. Set it at 20° advanced on tower #1 of the cap. I knew that if I still got a mysterious 20° retard, that this would tell me the Sniper was not at fault. I did, so the Sniper is good. That leaves me with the MSD 85551 distributor, the coil, or the MSD 6520 Digital-6 Plus box. The box is certainly wired correctly, I'm very sure of it.

    Since I'm getting a mysterious 20° retard in the equation, it negates my 18-20° of normal idle (initial) timing to be basically 0°. This is why the engine would hardly run, and wouldn't stay running unless I was on the throttle, to give it a little bit of advance timing. So, with my timing light over the past six days I have tested the timing while it was under the Sniper's control, and again now that it is under the distributors control. I HAVE TO GIVE IT 40° of timing (on the balancer) IN ORDER TO GET IT TO IDLE LIKE IT HAS 20°. When I rev it up to WOT, with the black 18° advance stop bushing, I get 58° on the balancer which in reality is 38° total. I AM COMPENSATING BY ADDING IN 20° ADVANCE TO CANCEL OUT THE 20° RETARD THAT IS COMING FROM AN UNKNOWN SOURCE! Totally crazy.

    These suggestions have already been discussed and tested in my post on the sniper forums:
    -My timing light (Innova) has worked with this particular msd setup for months. I know some lights don't work with MSD. Mine did; mine does. It has always shown me accurate timing numbers repeatedly, on this setup, prior to the car going haywire. I used to check timing all the time and it was working. The dial back feature is at 0.0° and has always been. This is not a timing light issue. Remember, the car ran fine in the morning and then was awful just hours later.
    - Cam gear spun or timing chain jumped. This would mean that I would have driveability issues and WOT issues ALL the time. If I add 20° advance to my distributor, the car will run as it normally does. It will idle great, it will drive great, it will WOT great and there's no loss of power. If a cam gear spun or chain jumped, I'm sure I'd have a loss of power right? Also, it's a brand new double row timing chain on a brand new engine and brand new cam, all built January 2020. Also if a gear spun or chain jumped, I find it highly unlikely it would be a dead on accurate reading of 20° that I would be seeing?
    - Wiring. I have NO RFI in my datalogs. I have Ohms tested ever single ignition wire and ensured the ones that are not used are shrink wrap-capped or depinned. my setup is clean, tidy & RFI free. I can show you photos if you would like; I keep thinks neat. This is not a mess of a car, it's the opposite. If it was an RFI issue, I would get erratic timing number changes, and I get a constant 20° retard, not any other values.
    - Rotor phasing, mine is dead on. I drilled holes in the cap and paint marked the rotor. I have videos on YouTube showing this. my YouTube username is the same as this username. Rotor phasing is currently correct ONLY because I am giving it 20° extra advance timing. If I take that 20° away, then the phasing is off, the engine will not run.
    - I also verified this 20° number when the Sniper was controlling the ignition about 15 separate times with the Static Timing Set check feature with different "set timing values". I always got the same result. 20° retard.

    My current thought process:
    Perhaps something is awry in the MSD 6520 digital 6 box. I have had this box for about 6 years now, and it has had to go back to MSD TWICE in that time for repairs. Once it totally died as I was driving, and the first time it was not acting right. Both times it has worked great after being repaired.
    - Would it make any feasible sense at all, that something has triggered/tripped/activated the "cranking timing retard" function on this box and it is now just ON forever? The function I'm talking about is where you (the box) can retard the cranking timing exactly 20° if you rotate the dial on the side of the box. Mine ALWAYS has been at #2 which is for "NO timing retard on a V8 engine". I have NEVER adjusted this dial. But what if something went wrong inside the box and electrically, it's now stuck to be "always activated"? Is there a way I can test this? Is this possible? I do not know how the circuitry of the box is setup, but is this actually possible? What can I do about it? Car runs and drives, but it needs me to give it an extra 20° (so 40° at idle and 58° at WOT on the balancer) in order to get it to run and drive. Bizarre! I can't be the only person this has ever happened to.
    Last edited by IROCZman15; 09-10-2020 at 11:11 PM.

  2. #2
    Join Date
    Jan 2010
    Brisbane, Australia


    Have you proved "true TDC"? A friend of mine blamed my timing light before I checked TDC with him, his balancer moved, some 70°. He chased his tail for low power for some time. Gary

  3. #3


    Yes, for sure. Using a spring loaded TDC tool several times over several days. It reads exactly on 0°. I used my finger in the hole a few dozen times. I even ordered the piston TDC whistle tool from Summit and that will be delivered tomorrow. I'm excited to try it out, but I'm certain that it'll give me the exact results as the spring loaded TDC tool. TDC for cylinder #1 is exactly 0° on my balancer.

    Even if my brand new SFI rated balancer had moved, it wouldn't have caused the abrupt problem that day. One moment the car was roaring around town, it sat for three hours, and when I started it up again it was totally awful. That's why it never struck me right away to check the timing, because I had the gut feeling that something failed or broke, not that something was out of adjustment or slipped loose. Additionally, I would have "fun" checking Static Timing Set numbers every few weeks during this year of driving the car. It was always dead on match to what the Sniper handheld showed and what the gun was reading on the balancer, and the Sniper was controlling timing for all these months.
    Last edited by IROCZman15; 09-09-2020 at 11:53 PM.

  4. #4
    Join Date
    Jan 2010
    Brisbane, Australia


    Yes, OK, sounds like mechanical is fine. I think you're "on the money" for the 6520 causing your loss of 20°. Is the pink wire connected? Gary

  5. #5


    I had this happen to me once. I got a pickup wire harness extension to connect the distributor to the MSD box mounted on the backside of the firewall behind the glovebox.
    The Purple & Green wires were correct on the distributor side, but they were reversed on the CDI box side. Green went to purple, Purple when to green. Had to repin that connector to get it to run right.
    Click image for larger version. 

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  6. #6


    Cool, thanks guys. calling MSD in about an hour.

    Gaz64: I don't want to get my hopes up, but I've slowly been eliminating other possibilities and the CDI box remains as the prime culprit. The pink wire is not connected to anything anymore. I used to run nitrous on the old engine and used that wire for a bunch of years, but on this new engine, I haven't put nitrous to it yet. So the pink wire is cut, shrink-wrap sealed with glue, wrapped in tape, and put into plastic loom.

    djh: I read about that same issue on a Chevelle or Nova website last last night when I was trying to dig in deeper to troubleshoot this issue. I can certainly try that today. However, the mystery still remains that this entire engine/ignition setup worked great from March - August 29 and was untouched. Then, in an instant, it was wildly different.

  7. #7


    Called MSD. Discussed every aspect of the system and what I've done so far for troubleshooting. He told me it's likely NOT the box, and likely NOT the "cranking timing retard function being stuck on permanently". I even tried to change the start retard setting to position #6 and it did its job by retarding the cranking spark and would not start the car. Switched it back to position #2 and the car fired right up. Darn, I was really hoping this would be a likely possibility. I'm just stumped about why I need to give an extra 20° advance to get this reliable engine to fire, run & rev. When I do, it runs great, just like it usually has for months. Baffling!

    He suggested that if the engine runs and is happy as I have it set now, to drive it this way. I'm in agreement, but this is not a permanent solution or even a fix. I'm afraid that whatever is causing the mystery 20° retard, is all of a sudden just going to "go back to normal" and all of a sudden I'll be having dangerous timing advance numbers. Man, this couldn't come at a worse time of the year really, just as peak car show and racing season is coming to NJ. Might try to borrow a 6 series CDI box from someone local. Thinking about making the car survive to wintertime and then sending the box to MSD for inspection. Also, considering switching to a HyperSpark system.

    While I'm under the hood, I'm going to install the new Y-splitter and 6' USB cable that I ordered from EFI Systems Pro. I'll do that today and see if I can get my laptop setup in the car for tuning. This whole recent troubleshooting dilemma really showed that it is a ton of extra work to have to save files/datalogs to the SD card, go inside, upload them, view them, make changes, and come back out to the garage to test them.
    Last edited by IROCZman15; 09-10-2020 at 11:12 PM.
    1987 IROC-Z Camaro. Street-Strip-Show-AutoX
    406 SBC, Dart SHP, Dart Pro1 heads, Holley Sniper EFI with HyperSpark. 700R-4 ProBuilt, Moser 12 bolt, UMI suspension with Konis, big brakes, lowered.

  8. #8


    I decided to install the Holley HyperSpark ignition system after reading about how well it works with the Holley Sniper EFI, and hoping that it would solve my mysterious 20° timing retard problem. I removed all of the MSD stuff very carefully and cleanly as I intend to sell it later on. I installed the new HyperSpark distributor, coil & CDI box. Got everything setup in the Sniper handheld and cranked over the engine. It started instantly and I just needed to tweak the timing, Inductive Delay and so forth. My mysterious 20° of timing retard was GONE!!! What a relief!

    I called MSD and updated them on the issue. I spoke to the tech who advised me to send the box in for a diagnosis so I shipped it out on Friday. I left a note in the shipping box about what I had experienced, and asked them to please let me know what the diagnosis is. If something is wrong with the box and it was indeed pulling timing away, then we have found our smoking gun. If the box is repairable, I'll get it repaired and shipped back to me with a clean bill of health. I then plan to sell it, the MSD coil, and my new MSD 85551 distributor, along with a spare cap and the phaseable rotor.

    So far, the HyperSpark is working great, but it does have a different look to it compared to my previous MSD system. (I liked the look of the MSD box better), but I certainly need the car to function properly.

    MSD setup:

    HyperSpark setup:

    I'll update this post after I hear back from MSD with hopefully a detailed answer about what went wrong with my Digital 6-Plus box.
    1987 IROC-Z Camaro. Street-Strip-Show-AutoX
    406 SBC, Dart SHP, Dart Pro1 heads, Holley Sniper EFI with HyperSpark. 700R-4 ProBuilt, Moser 12 bolt, UMI suspension with Konis, big brakes, lowered.

  9. #9


    Got the CDI box back from MSD. Had a few chats with one of the bosses (Ray) at MSD and they fixed some wiring on the box, then tested it afterwards. It came back OK, and they did an eight hour burn in of the box. Nobody seems to know what was wrong with it, but neither they (or I) can figure out what else could have caused my 20° retard of timing. All I know, is that it was happening (out of nowhere after working fine for months) with the MSD stuff, and the Holley HyperSpark system does not retard timing 20°. So it's not a car, Sniper, wiring issue on my end. Regardless. I'm going to try to re-coop most of the money I spent buying the HyperSpark system by selling the MSD CDI box, coil, distributor, wiring, spare cap, phaseable rotor. Going to put it on eBay as well as some car forums I belong to for a fair price.

  10. #10


    I guess I'm alone here on this one and seems to be the only one with this problem ever? It's quiet here all alone!

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