1974 230 ballast resistor and ignition control

[davidcwhitney]

Car has two ballast resistors as shown in wiring diagram. One is labeled 0,4 and the other 0,6. I assume these are resistance values in ohms. The diagram does not say which comes first in sequence.

Actual resistance values are 1.4 and 1.6 ohms respectively, and there's more resistance in the wires themselves, so my spark is weak. In addition, there is an ignition control unit below the battery tray. Can this unit be tested? Do they go bad? How much voltage does it want to see coming in, and does it change the voltage on the way out?

Per the wiring diagram, there is a connection from the ignition control unit to the coil, so no wire goes directly from ballast resistor to coil.

I know the coil likes to see at least 5v, but I want to know what's the max I can send it before I start burning up the points.

I am new to this type of car, so please be gentle.

Thanks,

David

[stevebfl]

The resistors are in series so when running it doesn't matter which order. When starting one is bypassed to up the voltage that has been reduced by the load of the starter. I don't remember which one gets bypassed but the drawing would tell you.

The points see no part of the load in that system, they are just a signal to the transistor to open and close the circuit.

Resistances in the 1 ohm range are hard to accurately measure. The best measurement would be the current flow. One could calculate the corresponding resistance by knowing the voltage drop on that current. I would expect 5-6 amps current.

[davidcwhitney]

I have not succeeded in making the car idle yet, so can't set the dwell on the new points. What's the point gap that corresponds to the correct dwell angle so I can at least be close and adjust later?

Also please see my questions above that were not answered in the initial reply, especially regarding the ignition control unit.

Thanks,

David

[stevebfl]

Set them to .018" and they will be fine.

The proper voltage is battery voltage minus the voltage drop that occurs over 1ohm. Voltage is battery, current is affected by coil resistance and I would suggest using the proper coil.