Hei Almost Done, Need Alittle Help.

I have a 1975 CJ5 258 with the old prestolite ignition. I am switching to a HEI. I've got it in and running. I'm going home today and finiishing it up. I have acouple of guestions though. On the prestolite is there a resitor in the coil + wire like the duraspark? Right know I have my power wire hooked up to the red wire leading to the control box on the fender. I checked it and it's 12 volts ignition on but 14 when running, Same thing with the + coil wire. If it's a 12 volt system how can I hit 14 volts?

 

Sorry, no answer for your resistor question.

The 14 volts is what your alternator puts out when charging. Think of Jeep wiring as a piping system: You need higher "electron pressure" from the alternator to fill up the battery.

Burn a wire? That is just the "Magic smoke" escaping from the electrical piping system!

 

"12V" is the battery voltage, not the charging voltage. IIRC the nominal voltage of the battery is actually 12.6V, twice the voltage of the old 6.3V systems.

The system voltage, when charging, can go higher than the battery voltage- it just depends on what the set point of the voltage regulator is. Run the alternator faster and you get more voltage.

From a quick look at my '77 factory service manual, I don't see any indication of an external resistor. You can test the 12V feed that you plan to use for the HEI by connecting it to ground through a resistor and measuring the voltage. If there is any resistance in the line, the resistor will act like a voltage divider and you will measure less than 12V.

 

Mugzilla, I have never heard of anyone else use the "Magic Smoke" term before. I started using that term a long time ago when I was in the Air Force (I work as an Electronics Tech) when we would find burned up parts. Every thing electronic is FM ("F"ing Magic) and if you let the Magic Smoke out it quits working. Hardest part I have found is catching all of the smoke and putting it back in.

 

Now I know who to quote when I use that analogy! I think we used the term every so often when I was in the Navy. Equipment would give up the ghost, and let out the smoke. 'd always hang a sign on broken equipment with "B.D.N.W.W." written on it.


BROKE D__K NO WORKIE WORKIE