Need help understanding Mopar ignition…no spark

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Put a meter on the battery while cranking. I had a weak battery do the same symptoms you have.
 
I have to ask the obvious question?

Is your timing set correctly? Did you set top dead center? Are you 180 degrees out?
 
Super-Cuda said:
I have to ask the obvious question?

Is your timing set correctly? Did you set top dead center? Are you 180 degrees out?
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Timing is good. it fired up fine when I moved it from the garage and then wouldn’t restart. I did check TDC though. Since then I did the GM HEI conversion so it’s not a timing issue but could be a distributor issue. right now I need it generate spark at the coil before I worry about distribution….

I measured the distributor inductive coil output while cranking and was getting an intermittent reading (As it was spinning) of 1 to 2.5 volts which seems right? The gap seemed right too.
 
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If you are referring to the pick up coil output, the voltage sounds about right. Voltage increases with rpm.
 
Sdriche said:
I measured the distributor inductive coil output while cranking and was getting an intermittent reading (As it was spinning) of 1 to 2.5 volts which seems right?
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No. How were you measuring?
Really need a scope to measure that. 10 to 12 KV would be more typical under load or snap acceleration.
eg.
1696173579113.png


This is a test for maximum coil output possible done by disconnecting one spark plug wire
1696173728170.png
 
Back things up a bit. People are going on about Mopar and you are mentioning HEI. WHICH DO YOU HAVE AKA what are you trying to use?

And what have you done exactly? Seems like HEI?

4pin-jpg-jpg.jpg
 
Sdriche said:
Yes it goes to 0 then shows voltage and keeps doing that. I assume it's when the star wheel hits the pick up coil. Should it be steady voltage when cranking?
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Switch your voltmeter to AC voltage.
 
67Dart273 said:
Back things up a bit. People are going on about Mopar and you are mentioning HEI. WHICH DO YOU HAVE AKA what are you trying to use?

And what have you done exactly? Seems like HEI?

View attachment 1716148657
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Take the diagram shown here and replace the coil, with a FD478 coil…I have this exact setup wired the exact same way, although I tested it with a canister coil too. I have a new GM hei module coming tomorrow…let’s see if that changes anything.
 
Sdriche said:
Take the diagram shown here and replace the coil, with a FD478 coil…I have this exact setup wired the exact same way, although I tested it with a canister coil too. I have a new GM hei module coming tomorrow…let’s see if that changes anything.
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You DID? break the "tit" off the bottom and mount it flat on something for a heat sink?

What did it do, AKA run for awhile and then quit? Do you have ANY coils lying around?

I would de-wire the power wire and hot wire it direct for testing. You should NOT be using a ballast.

CHECK WITH A METER to be sure you have full 12V to the module and the coil BOTH with key "in run" and with key "cranking"

Remove and "work" the distributor pickup connector in/ out several times to scrub the terminals and "feel" for tightness. Pay attention to the diagram polarity to establish what is called proper "rotor phasing." That will not prevent spark, but will offset the timing and cause issues.

I do not know anything about that particular coil. I will tell you that I ran an HEI module for two summers with the old canister stocker coil off my Dart, worked fine (no ballast)
 
That coil is a copy of the one that used to be used on HEI 6 cylinder chevy trucks
usully about $20 and perfect for the job

I run one works great.


do you have a tacho?
if so disconnect it and see if things improve

OR

do you have your coil wired in backwards swap the + and - connections over and see if things get better the + on that coil is the pair of spade connectors to the left of the lead that goes to the cap the negative is to the right. when the lead to the cap is closest to you.

you can't get this wrong in an origional install becasue the plug from the dizzy only goes on 1 way
when you wire it up with flying leads you can of course get it round the wrong way
having it the wrong way causes the spark to travel in the oposite direction across the plug gap......not optimal

+.......................................-
+.......................................-
....................* King lead to cap

The only other thing is having the pickup wired backwards
this causes rough running and varying advance, swapping this round involves reseting the timing bacause if its set to run nicely now it will be miles out when wires are swapped. the modue in most cases will run the car with this backwards, but just swapping the wires round doesn't necessarily result in a car that will start, you need to set the timing again.
balancer at 10BTDC rotor aligned with cap 1
close enough to start it. but then get the light on it and set it properly

last but not least i have had modules that just didn't work new out of the box...

if you have the hood up. check your earth strap from engine mount to chassis and chassie to battery.

motor won't run very well if it earths through radiator and throttle cable, the starter will labour and what the motor thinks is zero volts is not zero volts. if your module is earthed via its mounting bolt to a motor that isn't earthed to the chassis stuff just doesn't work proeprly

Dave
 
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one more thing
plug gaps need to be 40 to 45 thou
too small a gap creates a larger current, or at least a longer current flow, through the rotor button and the heat causes them to fall to bits
bigger gap increaes voltage, which reduces current, or at least the length of time that current flows for, keeps your little button in better shape
Original HEI had a metal rotor button not carbon.

don't go too big though, that just eats cap contacts and sprial wound leads

Dave
 
67Dart273 said:
You DID? break the "tit" off the bottom and mount it flat on something for a heat sink?

What did it do, AKA run for awhile and then quit? Do you have ANY coils lying around?

I would de-wire the power wire and hot wire it direct for testing. You should NOT be using a ballast.

CHECK WITH A METER to be sure you have full 12V to the module and the coil BOTH with key "in run" and with key "cranking"

Remove and "work" the distributor pickup connector in/ out several times to scrub the terminals and "feel" for tightness. Pay attention to the diagram polarity to establish what is called proper "rotor phasing." That will not prevent spark, but will offset the timing and cause issues.

I do not know anything about that particular coil. I will tell you that I ran an HEI module for two summers with the old canister stocker coil off my Dart, worked fine (no ballast)
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I appreciate the advice. The GM HEI is mounted to an aluminum plate with the correct paste. I tried 3 coils (original mopar, MSD cansiter, and the new FD478. I think i can rule out a coil failure. I verified a full 12v and despite the full 12v wired a relay direct to the battery to make sure.
 
Sdriche said:
I appreciate the advice. The GM HEI is mounted to an aluminum plate with the correct paste. I tried 3 coils (original mopar, MSD cansiter, and the new FD478. I think i can rule out a coil failure. I verified a full 12v and despite the full 12v wired a relay direct to the battery to make sure.
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Sounds like you are down to a trigger problem (distributor pickup or poor connections) or bad module

However DID YOU check the voltages as I outlined. This is IMPORTANT, AKA do you understand how the key/ IGN2/ bypass circuit works? You MUST check that you have power when cranking AND doing this while using the key rather than jumpering the start relay
 
67Dart273 said:
Sounds like you are down to a trigger problem (distributor pickup or poor connections) or bad module

However DID YOU check the voltages as I outlined. This is IMPORTANT, AKA do you understand how the key/ IGN2/ bypass circuit works? You MUST check that you have power when cranking AND doing this while using the key rather than jumpering the start relay
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I did check the voltages. There are 2 wires coming from the key switch, one with 12v key on and one with 12v crank. They both are wired to the module and to the + of the coil. I'm thinking trigger problem as well.....
 
UPDATE: Installed another new GM HEI module....now I have good spark from the coil. I guess the other [NEW] module from Amazon was bad. Car wanted to start but didn't. On to distribution....I'll recheck the plug gaps as I think they were .35 and as suggested should be .40 to .45 and make sure I'm getting good spark at the plugs. Getting closer!! TY for all the suggestions.
 
RustyRatRod said:
The coil is not a Chevy coil. It's a Ford coil. Standard Ignition FD478. FD is Standard's prefix for FORD. Ford, Lincoln, Mercury and Mazda.
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Don't be too hasty to dismiss :)

"that coil is a copy of the ones that used to be used on 6 cylinder chevy trucks"

same coil different manufacturer, Numerouse applications

my original was off a chevy truck but the core was rusty so i got a new one...

Cobra/Filko Ignition Coil NEW GM HEI ignition coil 1975-1984 GM 4cly/6cly | eBay

Interchange Part Number
GM600
Brand
Standard Motor Products
MPN.
DR-35
Manufacturer Part Number
DR35
Other Part Number
1115315, 1115324 1115444, 1115445 1115447, 1115448

can't say anything in repect to widing ratio but its approx 0.6 ohm primary and does the job very well indeed.

i wanted something with BIG iron core.. better flux carrying capacity. i want it in the core not messing with my radio.
looks crap but has to be better than the small plastic coated things look like they are off a motorcycle

Dave
 
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If you have a timing light, put it on #1 and view timing when cranking. It does two things, it will indicate plug is firing, and timing.

Four volts at run is very low, that may indicate bad bulk head connection for ignition circuit. Run power from battery hookup for test.
 
SOLVED - so my initial issue was a bad mopar orange ignition box. Replaced with a new (but bad) GM HEI module and replaced again with a good GM HEI. During troubleshooting i installed a new distributor rotor and cap and accidentally shifted all the wires one off. That was causing the no start even after i solved the no spark issue. I will say this...the GM HEI conversion, with the newer coil and NGK plugs gapped to .042 is amazing. Starts , idle and runs noticeably better. I left the old orange box and wires and taped everything up so it still looks stock. I wouldn't hesitate to recommend this conversion....even though i now have a GM module and Ford coil on a Mopar....i did it in a way where it's not noticeable and the car runs so much better. Thanks again for all the help you guys are amazing!!!
 
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