No spark!

[Vanspeed]

Hey guys, trying to get my roadster running and ran into a snag. Using a test light, I have power at the terminal box, power to the coil, but no spark from the coil wire. Coil and wire are new. If I turn the key on, I have power to the points. I tried turning on the key and holding the wire to a head bolt while cranking but there is no spark. The coil said 12v on it, and came with instructions saying if not used with a ballast resistor, it is 6 volt (from Snyders). Where should I trouble shoot? Wiring harness is also new.

[Mike V. Florida]

Sounds like the points are not making contact. With points closed no voltage at the points. Open the points and the battery voltage appears and the high voltage appears at the coil wire.

[Tom Wesenberg]

Yep, sounds like the points aren't working, or the distributor body isn't well grounded.

[Vanspeed]

I'm confused, If I have no spark at the coil wire, then the points wouldn't show a spark right? I thought the coil provided the spark to the points? If I stick the test light in the coil, where the wire would go, shouldn't it show a light when I crank the engine? I have it wired the same as my pickup and coupe. The points are opening and closing and they are clean.

[Tom Wesenberg]

The high tension spark is low in amperage and will not light a regular light bulb, but will make a neon bulb flash. The points turns the coil primary windings on and off, and if the condenser is doing it's job there should be little or no spark visible at the points, while running. You'll probably see some sparking while cranking though because a bit more current is flowing at cranking speed, or if you flick the points open with a screwdriver or finger. Points open you should have 6 volts at the movable contact, and when the points close you should have ground (0 volts) at the movable contact.

[Mike V. Florida]

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Originally Posted by Vanspeed

I'm confused, If I have no spark at the coil wire, then the points wouldn't show a spark right? I thought the coil provided the spark to the points? If I stick the test light in the coil, where the wire would go, shouldn't it show a light when I crank the engine? I have it wired the same as my pickup and coupe. The points are opening and closing and they are clean.

Ok let me see if this helps any, the points are a switch the "turns on and off" the high voltage from the center of the coil.

The condensor does two things, it help to keep the points from pitting an also supplies stored voltage to the coil.

The coil turns the battery voltage into thousands of volts to jump the gap at the spark plug.

So, 1) the points are closed and a connection from the battery through the coil and back to the battery is made.

2)The coil builds up a magnetic field during this time.

3)The points open, the coils magnetic field collapses and creates the high voltage that exits out the coil to the distributor and the plugs.

If the engine does not have a good connection to the battery, if the distributor does not have a good connection to the engine, if the points do not have a good connection to the distributor, if the points are dirty, then the connection through the coil to the battery will lessen the amount of voltage to the plugs.

This site may help as well. http://modelabasics.com/Ignition.htm

[BILL WILLIAMSON]

Find a book on basic point type ignition-101.
Ya' can't diagnosis it 'til you got the basic concept straight in your head. Forgive me for being blunt. Bill W.

[theHIGHLANDER]

Check your grounds and your contacts. Star washers are your friends.

[Vanspeed]

Ok, replaced the points with another set I had. I then was getting a spark. I could not for the life of me get it timed right though. I found the problem was the shaft that goes between the distributor drive and distributor was too short?? I cut it in half and and added 1/4 inch of steel to it. I then was able to get it to fire. Now I am trying to tune it (dual updraft carbs). Thanks for the input guys, it helped.