67CUDA "STEVE"
Member
What are the voltages that should be going to coil with the ignition in cranking, and what should be the voltage when it is running to the coil?
273 coil voltage help
- Thread starter 67CUDA "STEVE"
- Start date
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12 volts in start.
Reduced voltage in run, somwhere near 7.5 , I forget.
Reduced voltage in run, somwhere near 7.5 , I forget.
Rocky_JS
'cuda
welcome aboard Steve, I see your from Portland (Oregon) I suppose? I will check what your asking when I get home from work today. What is the problem your having?
BillGrissom
Well-Known Member
Ditto RedFish, assuming you have a stock ignition with points. About the same even if you have a later factory electronic ignition that still uses the ballast resistor. The ~7.5 V isn't actually steady. You would see the voltage pulsing on an O-scope, but most multimeters show the average value. If you don't have e-ignition, that would be the first upgrade, and consider an HEI system (many posts on FABO, $45 new or $15 junkyard).
This assumes that "when it is running to the coil" actually means "when the engine is running". Always review your questions. We don't usually know what "it" is and we can't know what you mean if you don't write it correctly.
This assumes that "when it is running to the coil" actually means "when the engine is running". Always review your questions. We don't usually know what "it" is and we can't know what you mean if you don't write it correctly.
I dont mean to seem argumentitive but...
The ballast resistor should not receive or send a pulse voltage.
If the voltage going to the coil pulses in run the voltage going into the ballast resistor would have to pulse. If that pulses the entire electrical system would have a pulse which is a failt somewhere. Most liely cause would be the old school mechanical voltage regulator.
The ballast resistor should not receive or send a pulse voltage.
If the voltage going to the coil pulses in run the voltage going into the ballast resistor would have to pulse. If that pulses the entire electrical system would have a pulse which is a failt somewhere. Most liely cause would be the old school mechanical voltage regulator.
BillGrissom
Well-Known Member
Actually I am just guessing, but I expect that if you put an O-scope on coil+, you would see the voltage fluctuating as the points open and close. That is because with the points closed you have effectively a voltage divider between the ballast and coil. There is no "voltage going into ...". Voltage doesn't flow, it is an "electrical pressure" at a point in the circuit, similar to fluid pressure in a pipe. I doubt you would see much pulsing on the upstream side of the ballast, since that is a fairly direct path from the battery, which is a big storage device.
67CUDA "STEVE"
Member
Thanks, Wires all over the place still. I reading the schematic for 67, still need to determine all the positions for ignition switch(key whole), don't want to mix the circuits up for the "on and start position", I know the on position will be used while the car running, but not sure how all circuit interacts exactly "Difference between the circuit in on position, and while running in the on position. Also have some intermitent problems to instrument cluster my circuit board needs to be replaced copper frayed up. Lots of work.
There is a lot of voltage fluctuation going on in the ignition system. Google primary ignition patterns and check out some of the patterns shown. The voltage flowing through the coil is constantly changing and being able to read these patterns can help find ignition faults. The voltage pattern on the plus side of the coil is smoother due to the inductance of the coil. You are correct, the battery pretty much dampens the fluctuations on the positive side of the ballast resistor.
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