My 71 Duster work in progress

[Dr.Jass]

Try unplugging the ECU and see what your readings are at the coil.

 

[Dr.Jass]

I just checked v at the ballast, nearly 11 in run, 12 in start. Checking at the coil, it's high 4s in run, 7s in start.

Is this on the ballast's output or right at the coil itself?

 

[Dr.Jass]

Also, on the clutch front, I know you can't tell from this, but it seems like a lot of free play to me. It's 100% moving the fork so the oval hole has nothing to do with this. You can see the rod to the fork moving.

It's very hard to tell from there, and the fork pushrod isn't a perfect fit on the countershaft either. You really have to measure the travel at the fork itself. 5/32" ain't much.

 

[b-body-bob]

Is this on the ballast's output or right at the coil itself?

Both. Higher numbers are at the ballast, lower numbers are at the coil.

I just checked v at the ballast, nearly 11 in run, 12 in start. Checking at the coil, it's high 4s in run, 7s in start.

You really have to measure the travel at the fork itself

Yeah I know but I'm tired of putting the dumb thing up on stands.

 

[b-body-bob]

Try unplugging the ECU and see what your readings are at the coil.

It was about 11v in both start and run positions.

 

[b-body-bob]

I tried that again and it was up to 12. It kind of wanders around.

I rang out the ECU wiring, it's all correct as expected. I replaced the ECU, scraped paint, verified ground. Same deal. Plug in the ECU and it drops to near nothing.

The ECU takes power off the ballast resistor on the run side; it's just a soldered in splice there. Is that the problem? The replacement ECU is an orange box with a Mopar sticker on it. It had been bolted down, but lightly, and the paint isn't stained so it wasn't under a hood for long.

 

[Dr.Jass]

Something's definitely wonky there. If you've got 11-12V at the ballast output but only 7 at the coil's (+) terminal, then that wire is suspect, but I wonder about the wiring itself since it's obviously not original--only a genuine 340 car could've had it, which is fairly uncommon, and it would've had a 4-pin. At one side of the ballast--the one feeding directly to coil (+), you should have two wires, both 14ga brown. One goes to the coil, the other to the start circuit on the ignition switch to bypass the ballast and provide full voltage when starting. On the ballast's other end, you should have one 16ga dark blue wire. It's fed by the run circuit of the ignition switch. There should also be an 18ga light blue wire with a yellow tracer that runs to the ECU.

In "START" both brown wires at the ballast and the one at the coil (+) should have nearly battery voltage. The other end should read about the same.
In "RUN" the brown wire, both at the coil and the ballast, should read ~8V, while the blue wire should have battery voltage or damned near it.

 

[b-body-bob]

Something's definitely wonky there. If you've got 11-12V at the ballast output but only 7 at the coil's (+) terminal, then that wire is suspect, but I wonder about the wiring itself since it's obviously not original--only a genuine 340 car could've had it, which is fairly uncommon, and it would've had a 4-pin. At one side of the ballast--the one feeding directly to coil (+), you should have two wires, both 14ga brown. One goes to the coil, the other to the start circuit on the ignition switch to bypass the ballast and provide full voltage when starting. On the ballast's other end, you should have one 16ga dark blue wire. It's fed by the run circuit of the ignition switch. There should also be an 18ga light blue wire with a yellow tracer that runs to the ECU.

In "START" both brown wires at the ballast and the one at the coil (+) should have nearly battery voltage. The other end should read about the same.
In "RUN" the brown wire, both at the coil and the ballast, should read ~8V, while the blue wire should have battery voltage or damned near it.

The ballast wiring seems correct. The ECU taps into the blue wire. The ECU plug/wiring harness is new. Just the voltages are wrong. There are no dirty terminals involved. It doesn't make sense. The voltage is correct in start and run until I plug in the ECU.

 

[b-body-bob]

FWIW I just read that the common MSD coils should be mounted vertically. So much for mounting one with a factory bracket. I'm pretty sure the one I've got has been mounted horizontally all along though.

I've got one of these too

 

[Dr.Jass]

If I had to guess, I'd say you've got a bad ECU. That's not surprising, since orange-box quality went to hell a couple of decades ago and never seemed to recover. I've always assumed that Chrysler changed vendors or their supplier got a bad run of parts, but it never got corrected. I know that by the time I swapped the 340 distributor into my Fifth Avenue (2003) I didn't trust new orange boxes and used an old blue one I had lying around instead.

I'd try performing the same tests with a different, known-working ECU. It doesn't have to be anything special; even a well-used original will suffice. I'd ship you one, but I don't know if I've got any lying around anymore. The only one I'm sure I have is the 5-pin off the '74 parts car.

FWIW I just read that the common MSD coils should be mounted vertically. So much for mounting one with a factory bracket. I'm pretty sure the one I've got has been mounted horizontally all along though.

I've got one of these too

I think the rule of thumb is that canister coils should be mounted upright regardless of brand. Lying on their sides facilitates oil leakage in the case of overheating or a seal failure. Truth is, if you boil it with too much voltage or dwell, the oil's coming out regardless. The 8203 in my '81 Imperial was upright on the firewall. It didn't help; oil was pouring down the sides onto the firewall and transmission.

There are only two kinds of coils in the world: Those for use with a ballast or resistance wire, and those for use without. Those for use without have the resistance built into the coil itself. Those for use with can usually be used on CDI or multi-spark ignitions without issue since those types of systems have little to no dwell.

I internally shorted the ballast on Agnes and left it in place to retain the stock look. I used a Pertronix 44001 coil (0.32Ω internal resistance), but that car has their Ignitor III module in a points distributor. According to their site, that coil can only have the ballast eliminated when using CDI or Ignitor II/III ignitions. Looking at some of their other offerings, they all seem to say the same thing, even though some have internal resistances as high as 3.0Ω. Unfortunately, Pertronix is now part of a conglomerate that includes your pals at Doug's, and since that merger I haven't found their tech support to be particularly useful. Internal resistance on the MSD 8203 is 0.7Ω.

I would think, but I can't swear that a coil with 1.5Ω or more internal resistance would be OK without the ballast. In that case the ballast is essentially just built into the coil (resulting in a hotter-running coil, of course). I have "no external resistor" coils in stock at the store, but I've never actually bothered to measure one.

 

[b-body-bob]

I'd try performing the same tests with a different, known-working ECU.

I did, but not known-working. The one that I started with was working when I drove the car into the garage. It had a voltage drop the last time I was fighting battles on it too. I had 3 4-pin and 2 5-pin units laying around. I chose the best looking one of the 4-pins.

Part of me questions if going to a 5-pin and a 4-pin ballast would help, since that kinda sorta separates the coil circuit from the ECU circuit.

I'm going to end up snipping that ballast wire off and rerunning it all, to the ballast, the ECU, and the coil. And I expect to still have a problem.

One thing I haven't tried is to disconnect the ballast and jump the wires together just to see if it makes a difference.

I think the rule of thumb is that canister coils should be mounted upright regardless of brand

Inquiring minds want to know why the hell the factory mounted them horizontally?

 

[b-body-bob]

OK, I took it to FABO and
halifaxhops said:
ECU draws alot of amps in the run position engine off. 4 amps usually running 2.5 ampsish. Prob what you are seeing.

Need to convert amps to volts to see if that pans out, which I can't do because I don't know the watts. Boo hiss. It does make sense though, and since I noticed it before all this work and back then the engine would start and run, it kind of bears out.

 

[b-body-bob]

OK, I accept that it's the same as it was when the 400 was running so it will run again, and continued checking the electrical. I walked around behind the car to check the backup lights (dash light works) and about the time I turned to look at the car I realized I didn't have the key on. But hey wait a minute, why are both brake lights on? It took a second for me to realize I forgot to re-adjust the switch at the pedal so I had to take the seat out one more time. That answers the question of why the ammeter shows a discharge.

Then when I used my phone to video the lights while I pressed the brake pedal, only the passenger side worked. Both sides worked before I fixed the switch so I just put that on my list of things that don't matter right now and moved on.

I'm pretty sure all I have left to do is to buy some vac hose for the advance, a can of gas, and find those long pieces of fuel hose I had just the other day. I don't entirely understand how I keep losing things in a 26x30 space, but I do.

Is 5 gallons enough to run the engine for half an hour? It should be, right?

 

[Dr.Jass]

Part of me questions if going to a 5-pin and a 4-pin ballast would help, since that kinda sorta separates the coil circuit from the ECU circuit.

It really doesn't. If you look at the factory setup, it's essentially just a jumper wire. I always wired for the 5-pin myself, because the 5-pin arrangement will run just fine on a 4-pin module. The opposite is not true.

ECU draws alot of amps in the run position engine off. 4 amps usually running 2.5 ampsish. Prob what you are seeing.

I don't understand this. The battery has more than enough reserve power to not sag ~4V at the ballast (either side). Most batteries sag maybe 2V with the starter engaged. Unfortunately at the moment I don't have a vehicle against which to test this, because the only runner is the '68, and it's points. Agnes has a Pertronix.

Still, to me something seems wonky.

Need to convert amps to volts to see if that pans out, which I can't do because...

...they're two completely-different measurements of different electrical properties. They don't convert to one another.

I think I know what you mean, though. I think what you'd want to do here is measure the resistance between the pin for the LBL/Y* wire at the ECU and ground so you have another variable for your maths. If you have other ECUs it might be worth checking multiples.

OK, I accept that it's the same as it was when the 400 was running so it will run again, and continued checking the electrical. I walked around behind the car to check the backup lights (dash light works) and about the time I turned to look at the car I realized I didn't have the key on. But hey wait a minute, why are both brake lights on? It took a second for me to realize I forgot to re-adjust the switch at the pedal so I had to take the seat out one more time. That answers the question of why the ammeter shows a discharge.

Then when I used my phone to video the lights while I pressed the brake pedal, only the passenger side worked. Both sides worked before I fixed the switch so I just put that on my list of things that don't matter right now and moved on.

I'd think you're looking at either a ground issue somewhere at the rear of the car, or something amiss with the turn-signal switch.

Is 5 gallons enough to run the engine for half an hour? It should be, right?

I would certainly think so. There's not much load on the engine in neutral so it shouldn't use nearly the fuel it would while driving.

 

[b-body-bob]

Unfortunately at the moment I don't have a vehicle against which to test this,

That's the first thing I thought, too bad I don't have another car to compare.

I'd think you're looking at either a ground issue somewhere at the rear of the car, or something amiss with the turn-signal switch.

I'll get it going again, it's just weird that both lights worked until I adjusted the brake light switch.

FWIW I had an apparently respected member over there ask me if I had the ballast resistor hooked up backward. I know that doesn't matter so I took the diplomatic route and said I didn't know you could do that, and explained the orientation of the ballast and the wire connections. Good grief.

 

[Dr.Jass]

FWIW I had an apparently respected member over there ask me if I had the ballast resistor hooked up backward. I know that doesn't matter so I took the diplomatic route and said I didn't know you could do that, and explained the orientation of the ballast and the wire connections. Good grief.

In somewhat defense of such a foolish statement, it's sort-of a plausible scenario. However, it's only possible on a 4-pin ballast if and only if the alignment pins have been broken off the connectors. If the pins are in place it can only connect correctly regardless of which end the connectors are installed.

Some of the old timers over there are revered because they've been there so long, not because they've got any particularly great knowledge. I can think of at least one off the top of my head who'll rant and actually insult people while being 100% wrong. I like that board well enough, but most of my time spent there is shopping in the classifieds.

 

[b-body-bob]

I can think of at least one off the top of my head who'll rant and actually insult people while being 100% wrong.

"At least" being the operative phrase in that sentence.

I browse there and sometimes offer advice but not often. I posted there a few times when we were sort of stuck on a problem here, hoping that more people bring fresh ideas.

 

[b-body-bob]

Well it's broken in now, but not broken. There are a few oil spots on the floor that shouldn't be there and the mech connection for the OP seeped a little but otherwise it survived.

According to the flaky-assed HF timing light/tach I used it ran at or above about 2300 for 30+ minutes. I pre-filled the bowls and thought at first it wasn't firing because it just spun over slick as anything. First thing I thought was to make sure the rotor was in the distributor. It was. Then I changed from the remote starter switch to the seat, partly because I thought we were done for the night, and boom it fired up almost immediately.

There's something clicking around the front of the motor. I don't think it's under the valve covers but who knows. The PS pump wasn't full and that might have been involved in it. Well, it started full but you know how that goes when the gearbox is dry. I was partly afraid to try to fill it more with the engine running, but mostly too busy doing other things.



Oh PS according to my mech temp gauge it didn't get above 160. I would say it's lying but the mech gauge didn't run high either.


There's a huge exhaust leak on the passenger's side, you can feel it pulsing beside the car.

After the half hour was up I tried to adjust the idle speed to get an idea of the cam lope but I had the cable way too tight so I couldn't set it below 1600. Instead of messing around with the hot engine I just turned it off and will do that next time.

Now to change the oil.

 

[RUSTY Cuda]

Congrats! always nice when a giant monkey wrench does NOT hit you in the head!

 

[b-body-bob]

It's kind of weird that it never got hot.

I couldn't find my IR thermometer so I couldn't really double check it. Everything was hot and pressurized so it was doing its thing.

That 400 engine would've been boiling after 1/2 hour.

I hope I didn't burn up the PS pump.