I have a 523 with Fast dual throttle body EZ EFI, Mallory Unilite distributor, and a Mallory Promaster 29440 coil using a ballast resister. I originally had a Mallory Hyfire ignition box that after running 10 minutes would lose the tach signal out of the box. It was so consistant it was easy to diagnose. After it initially stalled, it would take 2 minutes before it would start again, run about 3 minutes, then stall. It always started after 2 minutes. The box was 3 years old with about an hour run time. Since Mallory is no more, I switched to an MSD 6A box. I put about 12 miles on the car last fall, and let it run in the drive several times for maybe a total of 2 hours. It ran fine last year. Now, it seams to be doing the same thing. When it dies, I lose the tach signal out of MSD box. I show 0 RPM on the scanner and on my tach/dwell meter back probed in the connector of the MSD box. I don't lose 12v or ground at the box. I did notice that the LED indicator on the box stays on all of the time until it stalls, then it goes out and stays out until I cycle the key. I looked at the MSD box instructions and they state that the LED should go on momentarily with the ignition turned on and then go out until it is started, then flash with each trigger signal. It has never done that, it has always been on steady. I'm going to take the MSD box back and exchange it for another one since it's still under warranty, but I don't have confidence in this car with this ignition system. I'm very sure that it's not in the wiring of the car. All of the connectors that I used in the car are GM weather pack connectors, and after the issue last year, Ii took every connector back apart and double checked them. I even soldered the weather pack terminals in the ignition system wiring. For my 12v power, I removed the resistor wire from the engine compartment side of the bulkhead connector and used the same terminal on the dash side of the bulkhead connector. I've also got braided ground straps from the engine to the frame and 2 from the frame to the body. I've read the reviews on the MSD box and some say that they don't last long. For the EFI they recommend a CD box for a clean tach signal, They also state not to hook up the tach wire directly to the coil. Does anybody have any suggestions on a better system?
I have the MSD 6AL and the light is on whenever the key is on or engine running. Been years and it has not failed me. Had the 6A in the race car. It puked last year and went with the 7AL2. Its been perfect also. I run a Stinger dist in one car and a MSD in the other. Id say your issue is somewhere else. Seeing as it did the same thing with 2 different boxes.
I agree 100%! Thinking back, when I first installed the ignition coil, the instructions said do not use a ballast resister when using coil #29450, so I didn't. Before I replaced the Mallory box, I reread the instructions, this time with my glasses on and realized that my coil is a #29440, so I installed a ballast resistor, but I still had the same problem. I guess it's possible that coil was damaged. I think I'll run down to Summit tomorrow to exchange the box (since it's still under warranty), and pick up a new coil. Since Mallory is gone, any suggestions on a coil for my set up?Thanks, Jeff
With the MSD boxes, there is no reason to use a ballast resistor. The box gets its power directly from the battery. The box outputs 450 volts or more right to the coil. The wire that was a resistance wire, or had a ballast resistor in line, now simply turns on the box. You want 12 volts there, not reduced voltage. Make sure the coil you are using is compatible with the MSD box. MSD has a list of suitable coils. The only reason for a ballast resistor is to reduce the running voltage for points. You don't want reduced voltage for your turn on lead.
That's what I thought, but the instructions with the Mallory Promaster #29440 say to use a ballast resistor. The diagram shows it when using this coil with a Mallory Unilite electronic ignition. I got all of this from TA when they built my engine. Did I receive a mismatched combination? This is all new to me. I'm used to working with OEM components
A Mallory Unilite is not a CD ignition (Capacitive Discharge), the MSD 6A(L) box is. In a typical unilite install, the ballast resistor protects the module. If you are using the unilite distributor with a coil, the distributor connects to the coil. In an MSD install, the distributor simply triggers the box. The box fires the coil. The red lead simply turns the MSD box on, that's all it does. The Mallory Hyfire box would have been the same as an MSD box. No need for a ballast resistor. Here's a Hyfire box install instructions. And a Unilite MSD install diagram. Notice it says, "no ballast resistor necessary"
I see that in the MSD box instructions. Apparently, I was sold the wrong coil for my application. I'm going to try a different coil and see what happens. Well, on the brighter side, my back is feeling better due to a smaller, lighter wallet! Thanks for the info.
According to my MSD book, the Mallory 29440 coil is fine for use with MSD 6 series ignition boxes. Like I said, the red lead turns the box on and keeps it on as long as the key is in the run position. If you put a ballast resistor inline, or use the original resistor wire, it would drop voltage, maybe even more so as it got hot. That might not be enough to keep the box on. Just get rid of the ballast resistor and/or resistance wire. Make sure you have battery voltage at that wire when the ignition is on.
I have a mallory box and coil I removed from my car that has worked for years that is available. Needed to go with a 7531 MSD which can program advance curves , desired for procharging. I'm not far from you. gary
I'll remove the ballast resistor in the morning and see what happens. I don't think the neighbors would appreciate me running the car now. Thanks again.
I removed the ballast resistor yesterday and the problem seems to have gone away, and the car starts and idles better. I had the ballast resistor in the orange wire out of the MSD box. Is there a possibility that I damaged the MSD box? It's still under warranty so I can always exchange it for a new one.
No, I wouldn't worry about the box, it's probably fine. What you did was put the ballast resistor on the output wire to the coil. That is very different than installing it in a points system, or even an electronic ignition like Pertronix, Crane, etc. Those systems are inductive ignition systems. The coil is charged at battery or reduced voltage, and then the charge is interrupted and that generates a spark. The ballast resistor is installed in the line from the ignition switch, and drops the voltage in the run position to reduce arcing across the points. Electronic ignition systems control dwell time (time period coil is charged) to generate a hotter spark, so some of them can run on reduced voltage and still generate an improved spark. Some use battery voltage like the GM HEI. Some others use a ballast resistor, it varies by manufacturer, even by version. The MSD is not an inductive system, its a CD (capacitor discharge) system. The box gets battery voltage direct from the battery. It steps up that voltage and stores it in big capacitors. The distributor provides a trigger signal, and the capacitors discharge the voltage to the coil primary. The coil output wires (orange/black) deliver 450 volts or more to the coil primary when the box is triggered. That is the voltage the coil is supposed to get. Do you understand why putting the ballast resistor inline with the orange coil wire is a misapplication of that resistor? It probably got pretty hot after awhile. Read the description of the points system here, http://www.v8buick.com/index.php?th...ystem-function-tests-and-modification.248990/
