Balast Resistor voltage?

How many volts should be coming out of the ballast resistor to the positive side of the coil?

I have 5.5......is that correct or is my resistor bad?

Thanks

Depends on what's on the other side of the ballast.

Was that with the engine running?

From another thread where I posted the readings I got on my setup to help with a similar question.

Thanks, this is with the engine off and key to the run position. The battery was at 13.2 and 5.5 to the ballast and 5.4 to the coil.

The problem I encountered is a no start issue. and no spark to the plugs. I though maybe the ballast went bad....time to check some other things. Note. that the end of the ballast was loose, and when I tried to tight it, it broke off. so I need to replace that.

One side of your ballast should be real close to the same voltage as at the battery +. If it's not you have issues upstream of the ballast. Once you get the new ballast installed check that.

ballast is bypassed during start.
a bad ballast symptom would be car starts, and dies when you release the key.

your probably looking at bulkhead connector or switch.

since you get power in run, jump the starter relay and see if the car starts once you replace the ballast.

Thanks again, I didn't check what was coming in, only going out, as when I checked the positive side of the coil, the voltage was 5.4 (at the coil) so I decided to check what was coming out of the ballast to coil 5.5 volts. I can check the voltage to the ballast to see if its a 12.0 or better.

That voltage is pretty close to correct. Points or electronic? If points you probably have the points stuck closed. If electronic check the ignition box and its ground.

5.5 volts at the coil is probably a 1.25 or 1.5 ohm resister. want more voltage? try a .8 ohm msd resister. the resister you have is probably marked for ohm value, or just test it with a multi-meter. it's all pretty simple.

In Run, engine off, the voltage of the current flowing into the reistor should be within a 1/2 Volt of the battery reading taken at the same time.
I don't believe the battery was at 13.2 Volts while the key was switch on.
12.8 Volts is about maximum for the stored power.
Readings above that are usually surface charge. Surface charge disapates very quickly when a load is placed across the battery (flip the lights on, dome light, etc).

Under very heavy load, the votlage will termporarily drop lower. For example, during starting the voltage will drop down to 10 Volts or a even less depending on battery condition.

Chrysler tech used 9.6 Volts at the coil as the rule of thumb when measuring at the coil during start.
And a maximum of 1/2 Volt drop between battery and run circuit with key in run and engine off.
p. 9, 1969 Ignition System Analysis
http://www.imperialclub.com/Repair/Lit/Master/259/Page09.htm

Might want to print that pamphlet. Not sure how much longer the Imperial Club website will be around.
(link to larger printable version of available at bottom of page)

Thanks Jim, its still has points.

The battery was recently charged, as it had been sitting for a while, I will re-checked voltage tomorrow now that it has set for a few days.
Thanks for the link, I have some reading to do now.

I just noticed a small error in the illustration for testing voltage while the starter is cranking.
Key in start position, the switch connects only to the start ignition and starter relay wires.
Ignoring the starter relay, it should look like this.

One more small point. In general discussion including the manuals and most booklets BATTERY = POWER SUPPLY.
Keep in mind that when the engine is running, the actual power supply is usually the alternator.
The ammeter will show discharge any time the battery is supplying power.
If it is not discharging, then the alternator is supplying power.
So if you are checking for voltage drop when the alternator is providing power, measure from the alternator output stud, not the battery.