Has anybody had an MSD box that acted up from time to time, and worked fine other times? It was suggested tht a flakey MSD box might be responsible for the hard starting when the car is cold. There is experience to suggest this might be true. Again, anyone have one act up intermitantly?

Sam

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Yep. It's why I suggested it as a possibility. This was an MSD-6C (a regular MSD-6A but with a 5-pin Chrysler plug-on connector; they don't make them any more) on my '65. I had both the MSD and an HEI module in that car, the MSD on the driver's inner fender and the HEI on the passenger's. Just a couple of wires unsnapped and snapped together swapped between the systems. The night I installed them both, I hooked up the MSD and drove off. It worked well...most of the time. A few years later, the MSD box flaked on me in a downpour in a parking lot and I got drenched trying to figure out why I had no spark until I suddenly remembered I'd installed the backup HEI system. Swapped the wires, car started right up and I never had another ignition problem with that car, ever.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Interesting story Dan. But, did it fail, and then come back multple times? Before it failed completely, was it kind of goofy, and inconsistent? If so, tht would mirror the behavior of this box now. I'm trying to figure out if I s hould spend the money for a new one. I have been down so many hopeful roads that helped but didn;t cure, so to speak.

Sam

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I hadn't thought of it at the time ("Darn MSD box is getting flaky on me, durnit!"), but there had been strange failures to start on the first try that didn't seem fuel-related (turn the key off and try again and it'd fire right up) and those went away when I switched to the backup (HEI) system. I don't think this proves the MSD box itself was problematic. It could just as easily have been faulty wiring; I never diagnosed it thoroughly.

If I were you, I wouldn't spend for another MSD box, I'd toss a $24 HEI module in. Four wires, no waiting. Just to see what happens. At worst it doesn't fix the problem and you are now equipped with a backup ignition system.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Sam,

Don't buy another box. From what is inside the box, I doubt it is your problem. Check out my thread of late March for the strange failure I was having that turned out to be the MSD coil. The reverse engineered MSD internal schematic is referenced in it too.

rock
'64d100

I read the entire thread you reference, and am not sure where that leads me. I have a stock parts store coil now. I was considering getting a Blaster II just out of principal, but am not sure that is the wisest thing now. It seems I should track down Dan's HEI conversion thread, read it, and do that thing first.

What are the pluses and minuses of using one over the other. I have been putting MSD boxes on my cars since 1974, and never had a problem before, but certainly have heard of others having problems. I always carried the little jumper wire in the glove box for converting back to points if the thing failed, but never had to use it. Then later I was replacing solid state OEM ignitions, which probably had their reliability issues as well.

This sensativity to cold seems to be getting worse. Last year it started OK until the temp got below 50 degrees. Now it won;t stat below 60. Rock, what were you telling about the ice pack? I wasn't sure what this experiment showed you. Did your box fai below a certain temperature?

Sam

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If you think it's because the MSD is getting cold, try something that just keeps the MSD warm...............

(drop light next to it overnight should do it)

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Thanks for the tip Ems. I am through thinking I know anything. But, I am willing to try anything. The one t hing I have learned though, is to NEVER assume that just because it started OK this time I have hit on anything.

The one thing I am pretty sure is that whatever the culprit is, it is temperature related. When it gets warm, and stays warm, the car is pretty reliable, and runs pretty well. There is a shop locally here that specializes in putting EFI on race cars for rich guys. If I can;t get it worked out, maybe I will break down and see if they can figure this out.

Years ago there was a book that was titled something like, how to drive your car half a million miles. The premise was that certain things failed after a pretty much standard period of time, and that if you changed those things out before they failed, then you kept your confidence in the car, and would keep driving it. I don;t know if I totally buy the idea that a new part is always better than an old one, even if it has alot of miles on it. But, Maybe this is one of those things where it would not hurt to change the ignition after all these years and miles on this principle alone. The idea is that pre-empting a failure is better than waiting for it to die and leave you stranded on the road. I don;t know, just idle rambling on at this point.

Sam

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H'm. Often (not always, but often) electronic component failures work the other way round: no problem until the faulty component heats up.
But the idea to keep the MSD box warm during the normal cool-down period then try another cold start is a good diagnostic technique. Works on any electronic component — ignition box, ECU, voltage regulator, ignition coil, etc. A variant is pointing a hot hairdryer at the component and see if the failure can be made to show itself by this kind of accelerated-heating test.

But it'd be harder to arrange an accelerated-cooling kind of test. You could use dry ice or something, I guess...but the idea to keep the component from cooling down and see if the failure goes away is probably a good bit easier.

As for the ignition choice itself, from a performance perspective on a street-driven car — even a fairly hairy one — there is effectively no difference between HEI and MSD.

The HEI really is the best distributor-based electronic ignition system to come out of Detroit, and very probably the best of its kind in the world in terms of performance and reliability and — GM employing master cost-controllers — cost efficacy. More on why this is so at this thread(keep reading, scroll down) and here .
I agree with you in general. Sometimes, though, a parts swap really is the easier, less-costly way to test a suspect component.
There's an "idle calibration" joke in here somewhere, but I just can't quite find it...

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

The last MSD I had was "Fully Potted." This in itself could explain the "Cold" failure. With expansion and contraction over a long period of time, there can be environmentally induced breaks in circuits, if the delta is great enough, and it happens enough times. Like cold OSA temps and living in an engine compartment.

Just a couple of cents from a Twidget.

Even industrial sensors and electronics have finite limits within "preventative Maintenance Schedules." We generate those schedules for motors and sensors etc. based on our "Documented Experience" with them. Anything from exceeding tolerance to repair/replace documentation. I can look back though my records and tell within a year or so when something will quit on me.

For Industial suppliers, things become a bit odd due to the magic of statistics.
Mean Time Between Failure (MTBF) values with ridiculous numbers are decided based on the number of units failed in operation across one year.
For us that means we get a MTBF of 1000 Years if only one unit of a thousand fails in the first year. Clearly ludicrous.
The suppliers often will further cloud things up by identifying an "anomaly in the manufacturing process of Lot so and so," and disallow a data set that makes a part look bad.
You can't tell me that a PLC backplane is going to live 1,000 years. I can assure you that none of them will be working then.

CJ

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Part of Tyrde-Browne Racing

Sam,

I used ice to be sure it wasn't overheating. Many folks say the MSD boxes fail because they overheat. Well, failure when iced down sure wasn't an overheating failure, so the test elimnated that part of tracing the fault. I personally think many HEI and MSD overheat failures are reallly bad hat transfer condidtions, not necessarily location in the compartment. That is why I tested it on the engine, too.

But, no doubt as to the desirability of the HEI, as Dan has pointed out. Kinda like I had a pertronix before I heard of HEI, I had a MSD before getting hands on HEI. As a never finished piddler I put on both HEI and MSD to see what I thought of each....and I sure can't tell a lick of difference between them operationally. As with so many things, had I known of the cheap alternative before getting polydollars along, I would have started with HEI.

rock
'64d100

Not sure what "OSA" is, but this what you're talking about is a really good point. Mopar ECUs of the '80s and '90s (Logic and power modules, SMECs and SBECs) can show this kind of failure: The potting compound holds a component rigidly in place so it cannot move with thermal cycling, and eventually it breaks away from the circuit board. Or the potting compound itself shrinks or otherwise deforms with age and thermal cycling, yanking the component out of the circuit. It's often the cause of faulty voltage regulation in these cars. And come to think of it, now I'm reminded of my '91 Dodge Spirit R/T, on which line voltage would rise to ~16v with higher spikes when I started it from cold at outside temps lower than about 40°F (and there were many such starts in that part of Michigan). If I forgot and turned on the high beam lights before letting the engine bay (and SBEC) warm up, they would pop like flashbulbs, leaving little globs of molten metal where the filaments used to be. Once everything warmed up, the yanked component in the SBEC's voltage regulation or ambient temperature sensing section returned to its normal position and/or function, and everything worked fine.
From a ...?
That's sometimes possible on cars, too. "Oh, you've got a Mitsubishi 3.0 V6 in your Chrysler-product vehicle? At 70k miles give or take 10%, it's going to start smoking when the valve guides go away." Substitute Chrysler A604 or Ford AXOD transaxle, Ford 3.0 V6 head gasket, GM R4 a/c compressor shaft seal, etc.
How to Lie With Statistics, despite the usually-dry subject matter, is a very quick and entertaining read. I highly recommend it.
By this logic, if you're in a hurry on Thanksgiving and you forget to put the turkey in for five hours at 300°, you can put it in for half an hour at 3,000° instead and expose it to exactly the same total amount of thermal energy. ("Caution: emits showers of sparks.")
I would love to try that tactic if I'm pulled over by the cops in traffic. "Officer, this what you're objecting to was an anomaly in my driving. I hereby disallow it. It never happened."
I probably couldn't even if I knew what that is.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I've been planning a dyno shootout once I get my Dart running (that's still making progress...) to see if a HEI ignition and an MSD-6A make different amounts of power on a turbo motor or not. I suspect at higher levels of boost the HEI may not be as good. There's a couple other factory ignitions I'll be testing that may be able to beat the MSD-6, though.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

Wow, That was a facinating read. I didn't respond because I was fixing the garage roof, which is mostly done now. It still needs detail time and attention, but I don;t think it will fall down any time soon, and I can sleep better knowing I have already lifted a 530 lbs beam up 9 feet to the ceiling and secured it there.

Now that is done, If I go with the HEI ignition, how do I fire the tach? Is there a unit with a tach drive? I guess I should take out the instruction sheet for the tach, and see what they say huh? Thanks for all the thoughtful feedback. There were a few good jokes in there too.

Sam

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Just hook the tach wire up to the negative post of the ignition coil................

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes