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Discussion Starter · #1 ·
Guys, I tried this earlier, but where it went I do not know!!!!! My problem, and I hope someone can help, is that I've replaced my blown 258 with an earlier 304. I've decided to keep the point ignition that came with the 304 (I forgot to remove the system from the 258 before I dumped the motor) and am wondering if I have to use a ballast resister. I can't find if it has a resister wire leading to the coil. Anyone know?

 

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Check the voltage at the coil if it any higher than 9 volts...then yes....any thing lower than 6 something is wrong. The wire that suplied Voltage to the coil for the 258 WAS the resistor. Just keep in mind anything over 9 volts will not be healthy for the coil...it will probibly burn up.
Hope this helps

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1975 CJ5 304 V8
JEEP, Anything else is just a car
 

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You are correct about the voltages to the coil, (between 6 and 9 volts with the key in the 'Run' position, but I think you mis-spoke about the coil.
The coil doesn't care what voltage it sees (within reason), and can handle up to about 400 volts.
(400 volts in will really give the output a kick! Welcome to CDI output voltages!)
The reason the voltage is reduced is to keep from smoking the points. If you try to run a straight 12 volts to the points for very long, you will be walking shortly. The points will weld together.

Most starter solenoid have an 'I' terminal on them. The 'I' is for ignition. A wire should go from that terminal to the positive side of the coil with no resistor, so when you are trying to start the thing, you get hotter spark. When you let the key back to the 'Run' position, you should be on the resistor wire, or the ignition resisted circuit.

Check your voltage with the key in the 'Run' position, 6 to 9 volts should be the reading.
If you get 12 volts on this test, forget the resistor, and get an internally resisted coil.

Check your voltage with the key in the 'Start' position, the voltage should be 12 volts.
If you get less than 12 volts, or no volts at all, run a 12 AWG wire from the 'I' terminal on your starter solenoid to the ( ) positive side of the coil. Test again.

Check to see than the (-) negative side of the coil goes to the points.

You should be up and running.

So many cats, so few recipes...
 

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Well the reason that i said about the coil not taking over 9 volts is because I had one that fried when 12 Volts was hooked up to it..

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1975 CJ5 304 V8
JEEP, Anything else is just a car
 
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Discussion Starter · #5 ·
This I know - that if you put 12 Volts on the coils of the FI 4.0L Jeep motor, sometimes the coil will go out in just a few minutes and sometimes it will last for several weeks. But my experience is that it WILL go pop. The FSM also says it should be much less than 12 volts but I forget right now just what the called out value is.
sln

 

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A 4.0l HO spfi Jeep gets it's coil positive voltage directly from the A.S.D. relay, which is full battery voltage. On older point type ign. systems, you should have battery voltage during crank only, and dropped through a ballest resister in the run position. This can be wired using a standard I.S.O. relay to by-pass the ballest in the crank position, by robbing power from the starter motor. A cheap place for ballest resistors is from an older Dodge, about 2 bucks, and made of ceramic.

 
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