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Discussion Starter · #1 ·
Hello, first of all thank you in advance for any and all advice or input. I am new to the Mopar community. Loved them since I was a kid, but have just now been able to reach a point that I was able to purchase my first Mopar project.
I am currently working on a 74 Plymouth Roadrunner, with an Edelbrock modified 440, 727 Tourqueflite with TCI Street Fighter valve body, Mopar performance ignition, and a few other goodies. I purchased the car from a seller about 8 weeks ago, and the first day I got it out to drive I bottomed out and ripped a hole in the oil pan. It sat up for the last 6 weeks, but I recently finished getting the new pan installed, replaced the oil and zinc add, and put everything back together. Had to replace the battery yesterday and did so, now I can get the engine to turn over and rough start but will not idle. Just dies immediately. I can see a visual spark every couple of starts coming from plug number 7, as well as when I am able to get the engine to fire up blowing carbon out of the back. Any ideas what might be causing the car to not be able to stay cranked? I can provide other info if needed.
 

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I'd do a full tuneup. Sounds like bad plug wires.
 
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Hello, first of all thank you in advance for any and all advice or input. I am new to the Mopar community. Loved them since I was a kid, but have just now been able to reach a point that I was able to purchase my first Mopar project.
I am currently working on a 74 Plymouth Roadrunner, with an Edelbrock modified 440, 727 Tourqueflite with TCI Street Fighter valve body, Mopar performance ignition, and a few other goodies. I purchased the car from a seller about 8 weeks ago, and the first day I got it out to drive I bottomed out and ripped a hole in the oil pan. It sat up for the last 6 weeks, but I recently finished getting the new pan installed, replaced the oil and zinc add, and put everything back together. Had to replace the battery yesterday and did so, now I can get the engine to turn over and rough start but will not idle. Just dies immediately. I can see a visual spark every couple of starts coming from plug number 7, as well as when I am able to get the engine to fire up blowing carbon out of the back. Any ideas what might be causing the car to not be able to stay cranked? I can provide other info if needed.
As Bob suggested definitely check the plugs and plug wires. Also if "blowing carbon out of the back" means it's blowing black smoke when it does starts, that's a pretty clear indication of to much fuel. Check to make sure the choker isn't stuck or a float stuck in the carburetor.
 

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Many of the later Mopar Performance electronic ignition control modules aren't good.
These used to be a part than never failed, but that is no longer the case. If you have another module, even if it's a standard one, I'd swap it as there's not an easy test for them that i know of.
 
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replaced the oil and zinc add
zinc add? Why??
- did it run correctly before setting it into the ground?
- did you turn it off immidiately?
- have you checked that everything connected to the engine is still connected after this mishap? ( gasline, cooling, electrical..)
 
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Discussion Starter · #7 ·
zinc add? Why??
- did it run correctly before setting it into the ground?
- did you turn it off immidiately?
- have you checked that everything connected to the engine is still connected after this mishap? ( gasline, cooling, electrical..)
Yes everything ran correctly before having to swap
Out new pan. Had to remove carb to lift engine and replace pan. The zinc add is for the Flat Tappet Cams. Yes I believe everything is connected correctly. But I also think my air/fuel ratio may be completely out of whack
 

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Check for airleaks around carb and intake, loose hoses etc.
Since you have visibel sparks change leads and plugs.
- are the plugs black and or wet?
- how long did it run after ripping the pan open?
Check for flooding carb.
- skip the zinc add next time and get an oil that is good enough from scratch.
 

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Discussion Starter · #9 ·
I have to run a zinc add in it to keep the flat Tappet cams from wearing out and being too noisy. I am running Mobil 1 super synthetic, the oil should be plenty good. But the problem has been solved. Got the engine running. It was a coil problem.
 
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