Need help with electrical problem

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67dodgedartconv

67dodgedartconv

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My engine went from running well to progressiveIy running worse and now not running. I have a Pertronix ignitor ignition system. I am getting intermittent spark at the plugs when I ground them. With the key on in "run" and grounding a plug on the exhaust manifold I get an intermittent spark. But when I pull the distributor coil wire and ground it I get a consistent strong spark. Practically new plugs and wires and cap. Changed rotor but no change. Plugs are not oil or gas fouled. I replaced my firewall to block ground and put a new 4 gauge ground wire from the block to the frame. Any ideas why I'm getting intermittent spark when I am getting strong spark at the coil? Thanks for any help.
 
After about 1000 miles, my Petronix conversion failed.

So I converted it to a Mopar electronic unit & all was well!

Until......

The Petronix coil failed.

I put the 50 year old coil back in & all was well again. :)
 
Alaskan_TA said:
After about 1000 miles, my Petronix conversion failed.

So I converted it to a Mopar electronic unit & all was well!

Until......

The Petronix coil failed.

I put the 50 year old coil back in & all was well again. :)
Click to expand...
Changed the pertronix unit and coil but no change. Doesn't the fact that the coil is firing say that the coil and pertronix unit are good?
 
67dodgedartconv said:
Changed the pertronix unit and coil but no change. Doesn't the fact that the coil is firing say that the coil and pertronix unit are good?
Click to expand...

Sort of, or at least a little.
Are you getting a fuel shot down the carb when you work the inkage?
 
OK you are getting good spark out of the coil? Take a REALLY good look at the distributor cap and rotor ESPECIALLY the rotor. They can carbon/ punch through UNDER the contact finger and jump the spark down through to the shaft. Also look at the cap for moisture, dirt, tracking, etc.
 
67dodgedartconv said:
Yes, plenty of fuel shot . Practically new carb.
Click to expand...

Better be checking your timing then, and see if the chain jumped.
You said it has at least intermittent spark, so it should pop once in awhile at least.
Put a light on it and verify the timing. (Yes you can do that without the engine running)
It will also give you a better idea about your spark.
 
67Dart273 said:
OK you are getting good spark out of the coil? Take a REALLY good look at the distributor cap and rotor ESPECIALLY the rotor. They can carbon/ punch through UNDER the contact finger and jump the spark down through to the shaft. Also look at the cap for moisture, dirt, tracking, etc.
Click to expand...
Changed rotor but no change. Cap looks good. Practically new. This crap is driving me crazy. I had a problem very similar to this before and it was was original firewall to block ground was bad. Replaced it
TrailBeast said:
Better be checking your timing then, and see if the chain jumped.
You said it has at least intermittent spark, so it should pop once in awhile at least.
Put a light on it and verify the timing. (Yes you can do that without the engine running)
It will also give you a better idea about your spark.
Click to expand...
Pulled number one plug and put thumb over hole. Used remote starter switch. Turned engine over till compression blew thumb off. Timing was 10 to 15 BTBC. Rotor pointing at number one on cap.
 
I have had bad luck with coils. Replaced one that failed with an oreilly house brand because that is all they had. Lasted about a month. Ordered a borg Warner & opened the box & it was the same crappy coil. Bought a chrome mr gasket coil & it has worked fine.
 
Coils can certainly do something similar. Have you checked voltage at coil +? Both with key "in run" and engine stopped, and with engine running?
 
67Dart273 said:
Coils can certainly do something similar. Have you checked voltage at coil +? Both with key "in run" and engine stopped, and with engine running?
Click to expand...
I can't check it with engine running because I can't get it to start but don't know how to check coil. Can you explain how? I have a meter but suck at electrical stuff. If you put one lead on the coil + where does the other lead go? Thanks for your help.
 
You cannot really check a coil, only replace it. You can get an idea with resistance readings. Check the resistance between coil + and coil-. They should be very low. If you don't have a very good multimeter, with a low resistance scale, this won't tell you much

Check between the coil tower and either coil+ or coil-. Should be many K ohms. This reading will depend on the particular coil. What as exact as possible are you running for a coil, AKA OEM stock, Blaster II or what?
 
67Dart273 said:
You cannot really check a coil, only replace it. You can get an idea with resistance readings. Check the resistance between coil + and coil-. They should be very low. If you don't have a very good multimeter, with a low resistance scale, this won't tell you much

Check between the coil tower and either coil+ or coil-. Should be many K ohms. This reading will depend on the particular coil. What as exact as possible are you running for a coil, AKA OEM stock, Blaster II or what?
Click to expand...
Pertronix 40000 or 45000 volt coil. I have another one I will swap out tomorrow and check.
 
Coil is important. I run a Pertronix III with flamethrower coil approved for this. No solid wires! Must use suppressor style.

This has been the best and most reliable ignition I have tried thus far! Check the specs for your unit!
 
When I first fired the car after 25 years with Flamethrower III setup it lit up the engine bay with the old Taylor solid core wires. Sparks were flying everywhere with the old Solid wires that actually were still soft and supple. Went to the resistor wires in the same config with 45% plug boots for my 383 with stock manifolds and presto she was singing. They maybe Thunder Pro series. Get a good clamp die tool and straight and 90 ends for the dizzy side to ease installation.
 
Just checked. They are Street/Thunder series! 8MM.
 
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