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Topic Summary

Posted by: tow hook
« on: March 31, 2021, 01:19:25 PM »

Quote from: Slimpickins on March 30, 2021, 06:26:25 PM
Buck, I know this is a late post, but I had a similar issue. My problem was the wrong coil for my application.

I am not an electrician, but the way I understand it, there is a 1.5 and 3 ohm coil for 12 volt applications. The 1.5 ohm is typically for 8 cylinder engines and 3 ohm for 6 and 4 cylinder engines. Of course an 8 cylinder will discharge the coil more times per second than a 4 cylinder, so if you have the 1.5 ohm on a 4 cylinder engine, it is storing more current than intended, thus overheating.

Mine wouldn't completely die, but lose power the more I drove. I messed with float levels, fuel pump, changed plugs and ran compression checks. The spark plugs would be black as coal. I took off the NAPA coil, put on a Petronix 3ohm coil and my issues went away. The NAPA coil was a 1.5 ohm unit. It would also get smokin hot.

i did a pertronix set up, and had to swap coils as well. i grounded out the dist ( so the pertronix internals were fryed ) trying to swap a mom working oil pump. i put a old school points back in. it runs great for now. i'm sure i'll have to put the petronix pick up back in. but i know what i did wrong :(
Posted by: Slimpickins
« on: March 30, 2021, 06:26:25 PM »

Buck, I know this is a late post, but I had a similar issue. My problem was the wrong coil for my application.

I am not an electrician, but the way I understand it, there is a 1.5 and 3 ohm coil for 12 volt applications. The 1.5 ohm is typically for 8 cylinder engines and 3 ohm for 6 and 4 cylinder engines. Of course an 8 cylinder will discharge the coil more times per second than a 4 cylinder, so if you have the 1.5 ohm on a 4 cylinder engine, it is storing more current than intended, thus overheating.

Mine wouldn't completely die, but lose power the more I drove. I messed with float levels, fuel pump, changed plugs and ran compression checks. The spark plugs would be black as coal. I took off the NAPA coil, put on a Petronix 3ohm coil and my issues went away. The NAPA coil was a 1.5 ohm unit. It would also get smokin hot.

Posted by: Rus Curtis
« on: September 04, 2020, 02:45:30 PM »

Buck,
Your jeep will run for a while then die.  The coil gets hot. 

The charging system can affect engine run but what you usually see is a dead battery if not charging.  You'd notice this more when restarting as the starter drags more and more.  In extreme cases of depleted battery backup, you'd loose spark and the engine would die.  If after the engine dies, does the starter turn over at normal speed?  I'm not aware of charging systems typically fading during operation but have seen charging systems not provide output to run everything on the vehicle (and charge the battery).  Back in the day, on old vehicles, I'd do a shade-tree test on a charging system.  Start the vehicle, turn everything on possible, then disconnect the negative battery post.  The alternator should keep the vehicle running.  But to me it sounds like you're describing an issue other than charging.

Have you checked the coil?  It may be failing.  I've read a few threads on how to test both the primary and the secondary, but fortunately I haven't had your problem yet.
https://www.cj3b.info/Tech/IgnitionSpark.html

IF the coil has an internal resistor, an external resistor isn't needed.  Are your points burned? 



Posted by: buck toenges
« on: September 04, 2020, 11:16:36 AM »

I am having problems getting my 1 wire 12v alt system to work.  It runs fine for a while ( 15 minutes of driving) then dies.  The internal resistor coil is very hot.  I have a walcks wiring harness that I started with and then changed out the electrics to a 1 wire alt.  I have read up a lot about issues relating to changing over to a 1 wire alt system and think it is set up right.  I am running a wire on the pos side of the ammeter back to the positive lug to the battery.  I am using a solenoid and a key switch. I checked the ohms on the condenser and that looks fine.
 I am considering using an external resistor also to the mix because of the coil overheating.
I know I have 12 v at the positive at the coil when starting but haven't looked at the voltage at the pos+ side of coil after it is running.  I have gone over fuel related issues and think that it is o.k.  Even thought it might be vapor lock issues but I don't think that is it.  My main clue right now is that darn hot coil.

Thanks,
Buck