C with no spark

Deake

Member
There is not a spark from the coil wire, following John T's ignition troubleshooting guide, I find that there is voltage on the output terminal when the points are closed and none when they are open, seems as if something is reversed. Where should I look?
 
With the points open and the ignition switch on you should have battery voltage on both small terminals on the coil. If you're still using the 6 volt battery the wire from the coil should be on the + terminal of the coil to the points. The battery was positive grounded.

If it was converted to 12 volts the coil wire is on - minus terminal of the coil to your points.
Make sure your points are set at .020" on the distributor cam lobe. Use a volt meter to see if you're getting battery voltage to your coil. Hal
 
With the center high voltage coil wire 1/4" away from the engine block and attached to the coil(use tape).
And the trans in neutral brakes set.
Points open by being on the distributor cam high spot.
Distributor cap off and points visible.
Ignition turned on (for less than 3 minutes)
Use a screw driver to carefully bridge across the points. Just make contact across the two contacts making a connection. Make and break this connection with the screw driver. It should spark a little at the tip of the screw driver. It should spark a lot at the coil wire to block gap.
If not the points might be connected to the terminal wrong, shorting to the distributor housing. Or the wires are touching ground inside the distributor.
Let us know what you find. Jim
 
have you made sure the insulators on the little screw that goes through the dist. to points are good. that screw cannot touch ground.
 
"I find that there is voltage on the output terminal when the points are closed and none when they are open, seems as if something is reversed"

YES THATS BASS ACKWARDS

DEFINITIONS: (Regardless of Polarity)

The coils INPUT is the terminal that receives voltage via the Ignition switch when ON.

The coils OUTPUT is the terminal that wires to the little side post/terminal on the Distributor, and from there to the points and to ground when they are closed so coil conducts current.

A test lamp or voltmeter on the coils INPUT should light or register voltage (with respect to frame ground) anytime and all the time the IGN is ON. A test lamp on the coils OUTPUT (to distributor) should read voltage when points are OPEN but zero voltage (no light) when closed (cuz the points short it out to frame ground).

1) If the light on the output IS ALWAYS LIT EVEN IF POINTS ARE OPEN OR CLOSED...... The points are badly burned or not fully closing or aren't getting a good ground via the distributor or the wiring or wires aren't right or the wires open from coil to distributor THE COILS OUTPUT ISNT GETTING GROUNDED OUT SO COIL CURRENT FLOWS..

2) If the light on the coils output NEVER LIGHTS UP.......The coils LV primary (from little + and - terminals) is bad/open, it should be around 1.25 to 4 ohms NOT an open circuit,,,,,,,,,,,,,The points are remaining closed,,,,,,,,or the condenser is dead shorted (try disconnecting it),,,,,,,,,or the points or their wiring is shorted,,,,,,,,,or the distributors little side terminal pass through has bad insulation and is shorted out to case.

A lamp on the coils output should flash ON (points open) and OFF (points closed) as the engine is slowly cranked over.

Digest all this n let us know

John T
 
Frist of all thanks to everybody for responding. I'll try to respond.
John T.: I am pretty sure the problem is in the grounding of the distributor, just not sure where to look. What wires do you mean?
Jim: There is no spark across the points when I short them with a screw driver. What wires do you mean?
Hal: I am getting 6 volts at the input and 6volts at the output when the points are closed.
Rustred: I have not had a chance to check the insulation on the posts, will let you know about that tonight.
I have a little field I plant to corn every year and I'm going out to plow it with the M today before it rains. Gary
 
Is the plus side terminal on the coil going to the points? Your battery should be grounded on the + positive post. Hal
 
The wires inside the distributor that connect the condenser to the side terminal, and the spring/conductor that connects the points to that same terminal. If there is no sparking at the points with them open when bridged by a screw driver, the connection to the points (external wire or terminal on it) is internally broken or not connected. Distributors have been known to be not grounded (rarely) if so, a wire from one of the cap clip screws to the engine would work. Jim
 
I've checked all the wires, the isulation is good. How do I check if the distributor is grounded?
 

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