Ignition Demon 74 Slant 6

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Holden Customs

Holden Customs

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Hello everyone. I have been dealing with an ignition demon on my car and I have not been able to get spark. I have tried pretty much everything I can think of so now I am looking for some help. My car is a Canadian model 74 dart sport with a slant 6 and 904. I have rebuilt the engine and am now in the process of getting everything back together. What I started with was the stock ignition. I had a new 4 pin module, 4 pin ballast, new electronic distributor, ign relay, coil, plug wires, and plugs. I had everything hooked up as stock diagrams show and when I cranked the engine over I was getting no spark and the starter would very quickly die out like it drained the battery instantly. The battery mind you was also only 1 year old and hardly used. I ended up putting in a new starter (the mini one for a later model dakota) thinking that was the issue with it killing the battery so fast. Also, following a guide found here Replacing electronic ignition completely in 1970s-1980s Chrysler, Dodge, and Plymouth cars and trucks I upgraded my ignition system to use a HEI module from a chev vehicle. With that I also upgraded my coil to a flamethrower 3.0ohm model. Once I got this all installed when turning it over I still have the exact same problem as before, no spark, and the engine turns over for about 4 seconds and then it seems like the battery is dead. After this point I still have 12 volts at the battery and after a load test the battery is fine. I have also tried other batteries and it gave me the same result. As for spark, I have included a rough wiring diagram for how the hei module was installed and pictures of the wiring on the car aswell. I used a multimeter to check voltage and I am getting: (Run position: 12v at "B" of the Hei, 12v at "C" of the hei, 12v at both + and - sides of the coil, and the wires running to the electronic dist. both read 1.3v) (While Cranking: 8.5v at "B" of the hei, 8.5v at "C" of the Hei, 8.5v at both the + and - sides of the coil, and the dist wires still have 1.3v)

I have tried using the stock coil, a different cap and rotor, different plug wires, alternate batteries, and I still get the same results. I do know that the hei module is grounded aswell. The only thing in the ignition system that isnt new is the starter switch in the coloumn, but I assumed since there is 12v of power to all the right places in the car when it is in the run position and then the starter cranks over in start position that it is working correctly. Have I missed something in my wiring? Originally I thought there must have been an issue in the wiring of the stock igniton system which is why I upgraded to the HEI. Any help or thoughts is greatly appreciated.

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Ok just for starters, here is the definitive basic diagrams for GM and Mopar systems

Also, with everything off in the car for at least an hour, check the battery voltage right at the battery terminals. If it is less or much less than 12.2V charge the battery or have it tested. A NEW BATTERY (or any other component) is no guarantee that the component is "good" AKA "not defective."

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One danger you have is that because of a possible mistake, or even a defect in manufacture, you may have failed the module or it may just be defective. Keep that in mind

You have a multimeter? You need to make CERTAIN the module is grounded to the screw eyes through the module.

The module MUST be mounted flat, and there is originally a "tit" on the bottom you must cut/ file off.

CHECK that the module is grounded with an ohmeter.

Otherwise it appears wired correct, so............

See if the voltage is correct.........

With key in "run" the coil+ terminal should show +12 "same as battery"

With key in "start" the coil+ terminal should also show "same as battery" but it will be lower because of cranking current. Regardless you want at least 10.5V or higher

If you are NOT getting these readings, "rig" an alligator clip lead to jumper battery power direct to the coil +

ALSO HOW are you checking spark? You may have something as simple as a break right in the coil wire. "Rig" a test gap and SOLID core wire out of the coil tower. Crank the engine and see. You should get about 3/8 or more likely 1/2" long nice hot snappy blue spark.

CHECK the distributor connector and the pickup coil. Those connectors are notorious for getting corroded/ loosing connection Work the connector in/ out several times, and "feel" for tightness, then inspect with a light for corrosion. Measure for continuity. Because of your modification, you can check the connector.......remove the two connections at the module and check right there. Post back the resistance.

INSPECT the cap and rotor for damage, wet, dirt, etc. Inspect the reluctor and pickup for debri, rust, damage. CHECK the reluctor--to pickup gap. Should be .008" That's inches not metric. Use a brass feeler which you can buy at Oh'Reallys

Connect the dist. pickup to your multimeter set for low AC volts. Crank the engine or spin the dist. It should generate about 1V AC

++++++++++++++++++++++++++++++++++++++++++

So far as the cranking problem, AGAIN a multimeter. Since you have elected to "throw parts" (and money) at the problem it is less likely to be a bad starter or battery

So take your multimeter

Clip the meter to the starter "big' solenoid terminal. Clip the other end to the engine block. Crank the engine until the thing starts to drag down (but do not crank it more than say, 20-30 seconds) and notice the voltage reading WHILE CRANKING

I'm sure it will be low. Now CAREFULLY feel the battery cable end terminals and even along the cables (both ground and hot) for heated / hot areas

If this gives no result, "rig" a way to hold the probes while cranking the engine. I used to do this with a remote starter switch (switch with alligator clips) held in one hand while holding the meter probes. "Stab" the probes directly into the top of the battery terminals. Crank the engine and read the meter. You again, should have at least 10.5V

If not, the battery is defective or dead

Post back what you find
 
Last edited:
@67Dart273

The module is definitely grounded. Notches were made in the aluminum plate for the nubs that stick off the back and it is screwed into "clean" sheet metal. I have also checked the screw points with the multimeter.

As for the cranking voltage. Key in "run" voltage at the positive terminal is 12 volts (same as battery), and while cranking it drops to 8.5v roughly. This is from the "new" battery I mentioned after a full charge. Again with the starter test you described while cranking the voltage drops to 8.5 at the starter and battery. After cranking it is once again at 12 volts. The wires after this amount of time were in fact warm, maybe even a little hot.

I think this may be the battery after all if I am only seeing 8.5v considering the same battery was used with my stock setup and the hei now. As for the cranking issue I suppose that could be the wires for the starter as I am using the original ones.
 
Where are you measuring this 8.5? To put it another way, measure directly at the battery posts, this will tell you if the battery is holding up. If it is low at the posts, the battery is undercharged or defective, or the starter/ engine is drawing way too much current (Bad starter, bad engine bearings)
 
So am I reading this correctly? You changed your entire ignition system before you ever figured out what the problem was?
 
@67Dart273 Sorry for such a long gap. I got called out of town for work for the last few weeks. I am back working on my project again. So I measured the voltage at the posts of the battery and as it cranked over the voltage dropped from 12.5 to 9.5 right away, and then over the next few seconds all the way to 4.5v until it would no longer crank.
 
Instead of using the GM module, why not use the electronic system from another Mopar. Quite a few of the late model FM&J bodies had slants in them with electronic ignition.
 
@Demonracer I had just read a bunch about using the gm module on slant6.org so thats what I went with.

@67Dart273 I found someone with a good battery and I swapped it out to test it. Turns out thats what it was. Ive got 10.6 to 11.0 volts when cranking now. At the module aswell. And I checked a plug and there is spark now. Thanks for the help
 
!!GREAT!! Battery dead or bad? I guess you did try charging it?
 
........and another lesson.......for all of us......that newer, new. does not mean "functional"
 
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