ballest resistor different?

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mopar101

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Hello, I have a 69 Barracuda. I bought the car with a 1972 318 with electronic ignition. The motor was shot so I have put in a 1976 318 that I know runs well. This motor has a point distributor. When I leave the power on the ballast resistor starts to smoke. This car has two of them. The other seems fine. Is there a difference between the resistor for a electronic or point distributor? Thanks for your time.
 
no, don't leave power on!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! bad on coil, resistor and points
 
I'm no comprehending the reason for a points dist' in a 76 engine or in a 72 model car. Electronic ignition would be correct for both.
 
-If you have it wired correctly, it may be normal. With the engine off, pop the cap and put a clean piece of paper between the point contacts. This will ensure the circuit is open.Then if you have a voltmeter hook it to the coil plus. Turn on the key. Immediately there should be near battery voltage there And no smoking, because the circuit is open at the points, and no current is flowing.If it still smokes, its not wired right. Somewhere, somehow that circuit is passing juice. But if the resistor is happy and not smoking then the points may have been closed at the time of smoking.
-Now getting back to "may be normal". In my experience NEW resistors seem to have a break-in period, during which they smoke. It only lasts a short while. Maybe a minute or so. And if they become contaminated, they will smoke again. That resistor is exactly like your electric furnace, in that, current passing through it creates heat. As the resistor heats up it resists the current, kinda like a regulator, and the voltage through it drops some. The oems used this effect to provide near full battery voltage to the coil when cold and tapering to some lower voltage over a minute or two to save the points from prematurely burning up.The idea worked for many decades. The points not so much. Eventually they require replacement; either the contacts burn up, wear out, or oxidize to the point of failing to connect, or the rubbing block goes away. They often require adjustment 2 or 3 times a year and can last several years before requiring replacement. But maybe not if you leave the ignition on.The electronic ECUs survive left-ons very well. But thats why the ig.sw has an accessory position.
-Back to the beginning; If it continues to smoke with the points open, theres something wrong. Could be a shorted condenser(very rare), or pinched wire at/in the dizzy,or even a shorted coil. Process of elimination.A VOM will be your friend, forever. Save a car get a VOM, learn how to use it.lol
Happy hunting.
 
The car is a 69. The elec. dist. from the 72 motor is shot. The 76 "motor" came with the points dist. and it runs great so thought I would leave it for now. As far as the power on, the power stays on after you release the key from the start position. So I'm not understanding why I would not leave the power on. At any rate...does anyone know why the ballast resistor would start to smoke?
 
ballast resistors are made of ceramic and wire only. They do get extremely hot so any oil, water, whatever, on it would cause smoke for a while. There is nothing else in it's construction that should make smoke though.
Points ignition should have only basic wiring and single ballast resistor.
 
OK. Im confused. You say the power stays on when you release the key. That would be correct if you are releasing the key from cranking. OFF is one more position to the CCW. And one more position to the CCW after that is accessory. The power should be off in both OFF and ACC. IT should be ON in both START and RUN. If that is not how your switch works, either its bad or the wiring is bad. A wiring diagram and a VOM will be required to further diagnose it.
 
My understanding is that in 2-ballast cars (1976), the resistor to the ECU is 5 ohm and the resistor to the coil is 0.5 ohm. In points cars (1969), the single resistor is 0.5 ohm. However, it is very difficult to measure 0.5 ohm and the value changes as it heats up. Electronic ignition cars used a different coil. At least I have a coil that says "for use with electronic ignition only", so I don't think parts interchange perfectly. Best to remove the 2-ballast and use just a single "points ballast", plus a "points coil". You can leave the extra terminals (to ECU) hanging in space for now. Just one of the reasons I prefer HEI ignition - no ballast confusion.
 
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