ignition resistor question

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Rumblin_440

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Ok guys I have a 78 power wagon with a 440 swap and some serious wiring issues. The truck was a factory plow truck that someone removed and butchered the wiring on, not to mention the fact that the truck sat in a field for 14 years so rodents didnt help the situatuion much. As for my question when I start the truck it cranks fine but gets no spark to coil and I know the resistor is good I just replaced it twice. My question is do I still need to run through the resistor now that I have replaced the coil with a napa coil?? If not how do I go about safely bypassing the coil?? I know the best thing to do is replace wiring harness which is my winter project I just need to get some more work out of the truck during the warm months so this should hopefully hold me over.

Thanks for the help in advance
 
Check with trailbeast and get the hei set up he sells kits or you can build your own, you will be glad you did.
 
The problem here is that you could be ADDING problems by doing this conversion on a truck you cannot get to run

What could be the problem now?

Lots of things

The distributor could be bad. Pull the cap and inspect the pickup coil and reluctor for rust, debri, impact damage and wiggle the shaft, looking for excessive wear. The gap is to be set with a brass feeler (available at O'Reallys) at .008" That's inches, not metric

Even if / when you convert to HEI you'll need a working distributor

Hook the two distributor terminals to your multimeter set on low AC --that's right AC volts. Crank the engine, it should produce about 1V AC

Remove the ECU box scrape the mounting ears and firewall CLEAN and remount with star lock washers. The box MUST MUST be grounded. 14 years of rust..........................

Inspect the cap and rotor for moisture, dirt, grease, carbon tracking, spark punch through on the rotor. Do NOT check spark using the factory coil wire. Rather, hold a grounded probe, or "rig" a test gap, right at the coil itself.

Temporarily jumper a clip lead from a battery source (the starter relay battery stud) over to the coil + terminal. Don't leave this hooked longer than necessary to test.

"Wiggle" all connectors. Remove the distributor, ballast, and ECU connectors, and 'work' them in/out several times to scrub the terminals and 'feel' for tightness

Pull the distributor connector. Use a grounded clip lead. With the key in 'run' ground first one then the other of the distributor connector on the ignition harness end. One of the two should produce one spark each time.

Is the ECU wet / muddy/ dirty? That big transistor and heat sink is HOT above ground, with "high voltage" from the coil primary. IT WILL SHORT if it's wet and dirty and missfire and quit.
 
You didn't give us much to go on. Assuming the 78 has the factory Mopar ECU, you do need a ballast resistor unless your "NAPA coil" is a "ballasted coil", i.e. primary resistance >1.5 ohm. This also assumes your ECU is either a 4-pin type or the 5th pin is a "dummy" (infinite resistance to case) as most new ones are.

If you require a ballast and don't use one, it will run fine (even better) for a short time, but the coil will get too hot after ~5 min and start missing, especially under more throttle. No ballast may also overheat the ECU, but I am not positive. Can't touch the coil and smell paint melting = "too hot".
 
Ok I appreciate the info guys and the engine had not been sitting for 14 years it came running out of an even that had only been sitting for a couple months but still fired when I pulled it. The cap and rotor I replaced. Ill check the gap and give the ecu a good inspection to see if that may be the problem but what gets me is the fact that it fire every now and again. For example the truck has been sitting for a couple weeks bc I have been busy and when I parked it last it wouldn't for again. By just the other day I went out and cranked it for $#it$ and giggles and boom fired right up and has started find the last couple times I've cranked it...
 
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