Update to-64 Plymouth 273 Intermitent severe misfire.

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Wally-T

Wally-T

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Well I pulled the distributor today to give it a proper look over and cleaning. I checked the points gap and they were still at about .018 thou. Got down to the weights and found they were a little sticky, bushings were good. So I cleaned and lubed everything, installed a new condenser, set the points and put it back in the engine. I set the timing, hooked up a multi meter to the positive side of the coil in case the engine started to act up again and went for a drive. I drove 50km (30 miles) and not even a hiccup. I drove highway and city. I drove like I was at the drag strip and then like I was your grandpa and vice versa... Flawless. Of course it worked the same way yesterday before it screwed up so only time will tell.
Something I did see that I thought was strange though is that the voltage to the coil ranged from 10.8 to 12.3. The lower voltage was usually at idle where the higher voltage was only above idle. I know it'll fluctuate with charging voltage but I was under the impression that it was only supposed to be around 9 volts from the ballast resistor (the resistor is new also)
What's your experience with this guys? Thanks, Wally
 
0.018" seems a bit small for gap, I thought it was supposed to be approx 0.030"

The coil voltage will raise as RPM raises that is normal. Due to the opening and closing of the points faster at a higher RPM.

Don't know what it should be at a specific rpm.
 
Dana67Dart said:
0.018" seems a bit small for gap, I thought it was supposed to be approx 0.030"

The coil voltage will raise as RPM raises that is normal. Due to the opening and closing of the points faster at a higher RPM.

Don't know what it should be at a specific rpm.
Click to expand...
The gap is around .018. The dwell is 30°.
 
Wally-T said:
the coil ranged from 10.8 to 12.3.
Click to expand...

That is not unexpected. What does the battery run? That is charging voltage? Many of these girls overcharge and that is almost always because of wiring harness/ connector issues. I've written hundreds of posts on this subject, but the usual answer comes to voltage drop
 
67Dart273 said:
That is not unexpected. What does the battery run? That is charging voltage? Many of these girls overcharge and that is almost always because of wiring harness/ connector issues. I've written hundreds of posts on this subject, but the usual answer comes to voltage drop
Click to expand...
The charging voltage is around 14v. So I understand that the voltage will fluctuate with charging voltage but isn't the resistor supposed to hold it under 9 volts or there about?
 
Wally-T said:
The charging voltage is around 14v. So I understand that the voltage will fluctuate with charging voltage but isn't the resistor supposed to hold it under 9 volts or there about?
Click to expand...
Good question. It should but it is just a resister coil and not a regulator.
 
Wally-T said:
The charging voltage is around 14v. So I understand that the voltage will fluctuate with charging voltage but isn't the resistor supposed to hold it under 9 volts or there about?
Click to expand...
I meant did you actually measure battery charging voltage. The ballast is NEITHER a resistor or regulator in the usual sense. It is a BALLAST resistor, and reason it's called that is that it's made with certain alloy resistor wire so that it "ballasts" the output. In other words it attempts to prop up the output power at low current, and drops off the power output at higher current. "Works towards that end." It's done with the selected temperature coefficient of the resistance wire used. "Somewhere" buried in the data books is a temperature/ resistance curve of whatever alloy is used in them.
 
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