b-body-bob
Well-known member
Mo data - the ECU case has continuity with the battery - post, and there is no spark signaled from the coil wire with the ballast resistor bypassed.
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My 71 Duster work in progress
- Thread starter b-body-bob
- Start date
Dr.Jass
Pastor of Muppets
The ballast is automatically bypassed in the "start" position of the ignition switch... at least, it is as built originally.
When you're cranking and testing with your timing light, what's the terminus of the coil wire? Does it lead to ground, either on its free end or via the rotor to the plug wires/plugs? No eventual ground, no signal. The coil will not fire down a dead-end road.
Connect your DMM to measure resistance/continuity to battery (-) whilst cranking, with the other end on the negative side of the coil. You should see intermittent (pulsing) ground as the ECU charges, then releases the coil through the negative terminal. No pulsing to ground? The only things that leap to mind are a bad ECU, bad pickup coil, or too much air gap between pickup and reluctor (or you forgot to connect the distributor
). Bad pickups are pretty rare in that design, but with the DMM you can verify continuity between the orange and black wires (with considerable resistance), while making sure there's no short to ground. If it's open circuit, internally shorted across the wires, or shorted to ground, replace the pickup.
When you're cranking and testing with your timing light, what's the terminus of the coil wire? Does it lead to ground, either on its free end or via the rotor to the plug wires/plugs? No eventual ground, no signal. The coil will not fire down a dead-end road.
Connect your DMM to measure resistance/continuity to battery (-) whilst cranking, with the other end on the negative side of the coil. You should see intermittent (pulsing) ground as the ECU charges, then releases the coil through the negative terminal. No pulsing to ground? The only things that leap to mind are a bad ECU, bad pickup coil, or too much air gap between pickup and reluctor (or you forgot to connect the distributor
). Bad pickups are pretty rare in that design, but with the DMM you can verify continuity between the orange and black wires (with considerable resistance), while making sure there's no short to ground. If it's open circuit, internally shorted across the wires, or shorted to ground, replace the pickup.
b-body-bob
Well-known member
Yeah I understand how the ballast works in the start and run circuits. What I was talking about is both terminals unplugged from the ballast and a jumper connecting them together.
When I'm spinning the motor, it's via remote starter switch with the key in the run position. I don't have T-Rex arms but I can't reach inside and under the hood at the same time either.
The coil wire was connected to the distributor cap and the cap was on the distributor when I checked it. I just moved the pickup from #1 to the coil wire.
The distributor is connected, I just looked at that, and made sure the rotor was in there the other day.
I'll do that coil test tonight before I change anything else.
I read that the distributor can be tested by connecting to the leads in AC mode and spinning it with a drill. It should read about 1 volt on the DMM. I haven't done that yet.
Edited to add: I presume if the coil test shows the - pulsing to ground, the coil is at fault, if it doesn't, the ECU is the problem.
When I'm spinning the motor, it's via remote starter switch with the key in the run position. I don't have T-Rex arms but I can't reach inside and under the hood at the same time either.
The coil wire was connected to the distributor cap and the cap was on the distributor when I checked it. I just moved the pickup from #1 to the coil wire.
The distributor is connected, I just looked at that, and made sure the rotor was in there the other day.
I'll do that coil test tonight before I change anything else.
I read that the distributor can be tested by connecting to the leads in AC mode and spinning it with a drill. It should read about 1 volt on the DMM. I haven't done that yet.
Edited to add: I presume if the coil test shows the - pulsing to ground, the coil is at fault, if it doesn't, the ECU is the problem.
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b-body-bob
Well-known member
I did the coil test - nothing. I swapped the ECU for a used one and now I've got spark.
I had trouble getting the thing to run with the replacement ECU so I've gotta go swap the bad one for a new one (that's likely to be bad too), buy some fuel hose, clamps, a few electrical connectors I need. Hopefully I will be able to get it running after that, but I'm not holding my breath.
I had trouble getting the thing to run with the replacement ECU so I've gotta go swap the bad one for a new one (that's likely to be bad too), buy some fuel hose, clamps, a few electrical connectors I need. Hopefully I will be able to get it running after that, but I'm not holding my breath.
RUSTY Cuda
In over my head!
Wow, I'm thinking I'm gonna need a pro if I ever get to the "start up" point, I don't have the skills to do half of what you've been through, so glad the first car was rebuilt & running good before I took it apart, this one not so much!
Hope the new unit does the trick.
Hope the new unit does the trick.
b-body-bob
Well-known member
Mostly what it takes is patience and good advice.
I should've had this figured out a week ago but I kept falling back into that voltage drop trap.
One piece of advice I would give anyone - stay away from big block A-bodies. Everything's more complicated than it should be because the fit is so congested.
Dr.Jass
Pastor of Muppets
I'd qualify that statement a bit:
"Stay away from big-block A-bodies unless it's 100% original or you're going to build it yourself from the ground up."
You had the unfortunate circumstance of buying someone else's project, not knowing any of the half-assery involved when you did so. You knew it had elephant ears but not that the engine location wasn't given much thought (beyond maybe header clearance?). The engine wiring harness was likely butchered to do it, but that's not the kind of thing that jumps to mind immediately when buying a car (especially if it ran). The true condition/build level of your engine and transmission are still question marks. You sauntered into the half-done project of a mentally-unstable individual.
On the other hand, had you bought a Duster with an empty engine bay or an engine you planned to remove forthwith, I'd wager half the problems thus far might not have occurred. Knowing exactly what you have initially makes an enormous difference: "I've got a 318 car into which this here 400 is going. The wiring isn't going to work as-is. I'm going to need either swap mounts or a factory B/RB K-member. There are only a couple of header manufacturers that won't require cutting the inner fenders but that's going to require a later-model or custom starter. The driveshaft is going to be wrong." You're aware of what needs to be done, rather than stabbing at or discovering what needs to be redone. And that, my friend, makes all the difference in the world. You'd probably have been better off in the long run ripping the engine/trans, elephant ears, and engine wiring out of the car and keeping only the former. "Now, how do I correctly make this engine fit and function?"
Though the confines aren't quite the same, putting a W2 engine and 4-speed into a slant six automatic car had its own considerations. The OE engine harness is now a connector donor; I went ahead and sprang for a repro 1969 340 engine harness (using a 30% off sale code, of course). I used known-workable V8 adapter mounts, despite knowing the location of several V8 K-members I could've used. I knew I didn't want the breakage-prone 1960-'72 transmission mount on a 4-speed behind a high-powered V8. The driveshaft wasn't going to work but upgrading that was a given at the outset.
The point is, I had a list. I knew what had to be done. The two biggest tribulations I had were in trying to be frugal by using 1/2"-thick adapters to convert the W2 exhaust port to a standard LA header (absolutely not happening in an A-body) and finding a '73-up trans crossmember. I wasted several days of my life on making, then trying to get those exhaust-port adapters to fit. That was a problem I created by avoiding a known-good configuration (the TTi headers). The trans crossmember was a bolt-in once I found one. The conversion motor mounts required a 3/16" spacer between the LH insulator and the mount to lift the TTi header off the steering box--easy fix, but that was the only real compatibility issue I had to discover. Any other problems I encountered were generally of my own creation: using the scattershield, installing a clutch switch the car would've never even originaly had (clutch switches didn't exist pre-'70) etc.
I'll say this: that Year One engine harness was a godsend. All the right wires in all the right places, and all known good--not 50+ years old. I modified one wire in order to use a '70-up voltage regulator. Everything else was perfect, leaving me lots of time to create my own issues.
While I realize there's no B/RB '71 Duster, the engine harness for a '71 Duster 340 with electronic ignition (it was available in '71) would only require lengthening the coil and distributor wiring. You don't even have to cut the distributor harness; just lengthen a Hopkins part #47965 or recycle two pigtails from distributors/harnesses). "I know there are no wiring issues between the firewall and core support" is an enormously-good feeling, trust me.The big-block A-body swap was not only a factory option, it's something that has been replicated literally thousands of times with good results. It's a great swap when you know exactly what lies ahead, including the expense. In your case, half of the issue has been what lay behind, i.e. "exactly what did this hammerhead do?" or "what was he thinking?" It seems most of your time on this project has been chasing down those questions and issues. Those are the least-fun problems to have.
Perhaps a better warning would be "Avoid someone else's half-baked, half-finished bullshit project no matter how appealing the final product might be."
b-body-bob
Well-known member
So true. After all the guy did shoot himself.
You're absolutely right. If I live long enough and stay healthy I'll eventually swap it to manual steering, trim the k-frame for the oil pump, and run adapter mounts. That might happen this winter since there's a 440 and 727 that I know a little bit about that will be sitting around. A guy recently "stabbed" a 440 and 727 with Schumacher headers on it into a Duster. I provided him with some photos to give him an idea of how he'd need to maneuver it into place. It's do-able - he had two helpers s- o I might not be able to do it alone without banging up a thing or two.
I've also got a couple of B blocks still at the prior owner's house. Long story short she's just weird, she doesn't want people in her house, and after you've been in her house, you don't want to ever go back. But anyway it looked like there was two complete engines, disassembled and stored in pickle buckets. So that's a start on a 451 or better.
FWIW I mostly came here to say, I now have a second Carquest ECU that won't spark, from two different stores. Refund this time. I had such a hassle there this morning I told myself these places can stick their discounts and I'll just go to NAPA where the workers seem to care. But I have to go back to get a refund.
The ECU that does spark is the one that came on the car. It wasn't in the car when it started not starting, so at least it wouldn't seem to be involved in the cause. It might be OK, but I'd still rather have a new one, no matter how irrational that is since we're talking about electronics.
When I crank the engine over with the working ECU in it, there's no mistaking it firing. I never thought of it, but now that it's uncapped, ignition is happening right near the end of the pipes and they're basically pointing straight down.
b-body-bob
Well-known member
Also, the final product was never that appealing to me. It was cheap the widow needed money and I could use something to do - the next thing you know I've got a car. I never aspired to owning a big block A-body. IMO they're kind of unnecessary - a small block will do the trick every time.
And you're right - I still might not have it all together but I wouldn't be in a worse place. I thought of that after buying brakes/suspension parts - "why didn't I just start with an aftermarket k-frame and a modern hemi?" but I pressed on.
Part of it is because I've already got the road runner torn down, and my history is that if they come apart they might not get finished. See once the engine's out, the bay needs painted. That's your first step down the road that leads to hell right there. I can't paint, don't have a place to paint, and have had trouble hiring people to paint. Purgatory.
I messed around with it yesterday but never did get it to run. It would fire off, but quickly die. The car has a choke and it's set correctly, so it oughta keep going.
I did get a decent bike ride in yesterday - the first in about a month thanks to rainy weather, covid, and me being lazy. There was a downpour again last night and it's supposed to keep coming off and on for the next several days. So much for that.
b-body-bob
Well-known member
Sure wish I would've checked this sooner. But nobody expects the Spanish Inquisition.
That's a pretty healthy gap there.
It fired right up after I fixed that. That was the problem that somehow followed me changing jets and ending up with me chasing the wrong tail until the starter went out.
You see how the pivot hole is wallowed out? Notice it looks like it isn't sitting on the rivet either? On this distributor, the original pickup assembly lifted right off. I thought that meant you could replace just that, and not the plate and all. I had another another old distributor that was worn out and I thought it was the odd man out so I drilled the rivet to get the pickup and install it in the first distributor. Turns out I had it backward, and you replace plate and all. I need to buy a new one.
That's a pretty healthy gap there.
It fired right up after I fixed that. That was the problem that somehow followed me changing jets and ending up with me chasing the wrong tail until the starter went out.
You see how the pivot hole is wallowed out? Notice it looks like it isn't sitting on the rivet either? On this distributor, the original pickup assembly lifted right off. I thought that meant you could replace just that, and not the plate and all. I had another another old distributor that was worn out and I thought it was the odd man out so I drilled the rivet to get the pickup and install it in the first distributor. Turns out I had it backward, and you replace plate and all. I need to buy a new one.
Dr.Jass
Pastor of Muppets
I'm almost positive I've mentioned checking that on more than one occasion, going back to at least late last year.
Your "bad" ECUs may not have been bad after all... just misunderstood. The gap distance directly affects the strength of the signal getting to the ECU--something I'm sure you already knew but definitely have learned now. The gap should be set using a .008" feeler gauge, preferably brass, between the reluctor and pickup. Per the '72 Plymouth FSM, a .010" feeler gauge should not slip into that gap--it can be forced ("DO NOT USE FORCE") but should not fit easily.
Also per the same manual, primary ballast resistance should be between 0.50-0.60 ohms, which is lower than I thought. The '73 FSM, which is the newest I have, bears this out.
On changing the pickup: I have a genuine OE Mopar pickup new in its sealed package. It does not include the plate to which the pickup is mounted, only the pickup itself (and possibly a screw--I haven't seen it in awhile). That leads me to believe that while the '72-'73 FSMs say the pickup and plate are serviced as an assembly, in later years the rivet got drilled and replaced by a self-tapping machine screw. The fact that the wiring on mine is black and yellow (rather than orange) tells me this change may have happened around the time dual-pickup distributors started coming on-line in the late 1970s. I also have an NOS dual-pickup distributor from an early-'80s truck 360. One set of wiring is black and orange, the other black and yellow. Both pickups are riveted to the plate. The upshot of all this is that if you replace the OE rivet with an appropriately-sized self-tapping machine screw, use the original hold-down/adjustment screw, and maybe a drop of blue threadlocker on each, you should be 100% fine. However, if you want to stick with the factory arrangment (and I wouldn't blame you), Standard Motor Products part #LX102 is a complete pickup/plate assembly, riveted just like the original. For stuff like this, I only recommend non-T series Standard-brand parts.
b-body-bob
Well-known member
I've had it apart several times, remember I changed springs and put an FBO plate it it so the distributor has been completely apart. I just hadn't had it apart since the stupid thing quit running. I didn't expect that to slip, of all things, but it did.
Yeah I figure every one of the ECUs I've got here are OK. I ended up just leaving that old one on it so I didn't buy a new one. Now I'm going to pick up a (looks above) #LX102 pickup assembly before I start driving the car around again. It's a miracle it didn't strand me by the side of the road - although I admit, it tried but somehow I kept it running long enough to get it home.
For some reason I had 1.2 Ohms stuck in my head for the ballast resistor until I found out recently that's wrong. I've got the wires directly connected now, sure I could've gotten fancy and hollowed out the resistor etc but that would require running out to fetch a soldering tip and it's no secret I'm lazy.
Right now I just want the dumb thing out of my garage so I can get the engine/trans out of the A12 before the resto guy calls my number. I'm on my way next door to rearrange things so I can get it in the basement garage.
I didn't expect that to slip, of all things, but it did.Yeah I figure every one of the ECUs I've got here are OK. I ended up just leaving that old one on it so I didn't buy a new one. Now I'm going to pick up a (looks above) #LX102 pickup assembly before I start driving the car around again. It's a miracle it didn't strand me by the side of the road - although I admit, it tried but somehow I kept it running long enough to get it home.
For some reason I had 1.2 Ohms stuck in my head for the ballast resistor until I found out recently that's wrong. I've got the wires directly connected now, sure I could've gotten fancy and hollowed out the resistor etc but that would require running out to fetch a soldering tip and it's no secret I'm lazy.
Right now I just want the dumb thing out of my garage so I can get the engine/trans out of the A12 before the resto guy calls my number. I'm on my way next door to rearrange things so I can get it in the basement garage.
Dr.Jass
Pastor of Muppets
I'm not sure what coil you're using, but a factory coil (or anything designed for use with a resistor) will fail in a matter of minutes with the resistor bypassed. In fact, the MSD Blaster 2 that comes with a ballast resistor in the package needs to have that resistor installed in series with the original. Ax me where I learned these facts. 
b-body-bob
Well-known member
The blaster coil I've got is spec'ed to work on 12v so it's OK.I'm not sure what coil you're using, but a factory coil (or anything designed for use with a resistor) will fail in a matter of minutes with the resistor bypassed. In fact, the MSD Blaster 2 that comes with a ballast resistor in the package needs to have that resistor installed in series with the original. Ax me where I learned these facts.
I forgot to refill the power steering so I had to strong arm it next door but it's moved now.
RUSTY Cuda
In over my head!
Sounds pretty good, motion is a good thing!
thrashingcows
Drowning deep in my sea of loathing...so I'm
I've been patiently waiting for the day that you got it fired up and running...sounds awesome! 
b-body-bob
Well-known member
I've been the exact opposite of patient - when I got it moved I pretty much just went to bed. It's been exhausting running a race against time. Taking the A12 apart so it's ready to go isn't stressful at all because I know I can just put the pedal down and get it done.I've been patiently waiting for the day that you got it fired up and running...sounds awesome!
