C with no spark

[Deake]

I am getting voltage on both coil posts when the points are closed, but none when they are open. It seems like the points need to be closed to complete the circut. Should I be getting voltage on the high coil post regardless if the points are open or closed?

 

[Janicholson]

Possible bad wire/connection/switch in the system.
Any time the voltage at the switch side of the coil goes away, it is a supply side issue. The ignition push pull button turns on voltage to the coil. The coil is grounded on its other terminal through the points. This means the small wire from the coil to the distributor connects to the movable point in the points. The fixed point grounds the system turning on current flow through the coil. (in preparation for the points opening which makes the spark as the current through the coil drops to zero) if the supply voltage is through a very poor connection, the meter will read it as OK. but when placed under load (points closed) the voltage goes to zero. Jim

 

[John T]

"Should I be getting voltage on the high coil post regardless if the points are open or closed? "

YES If the Igntion circuit, its BAT input terminal is hot and the switch is good, WHEN ITS ON THERE SHOULD ALWAYS BE VOLTAGE ON THE COILS INPUT (NOT output side to distributor) WITH RESPECT TO FRAME GROUND. If theres a ballast resistor it has to be in place and good also

Over on the coils Output (to Distributor) there should be voltage (with respect to frame ground) when the points are Open, but no voltage when closed.

If you put a test lamp on the coils output or distributors small side input terminal and crank the engine over slowly with Ign ON, the light should flash ON when points are open but OFF when closed.

If the light is never on, the points are closed,,,,,, or shorted out,,,,,,,,, or the condensors a dead short,,,,,,,,,,or theres a short in the wiring or points or the distributors terminal is shorted to case,,,,,,,,,,,,,or the coils LV primary is bad/open.

If the light never goes off, the points are badly burned or not fully closing or the points or distributor isn't grounded or the wires open from coil to distributor.

See my Troubleshooting procedure

John T
John Ts Ignition Troubleshooting