Suddenly won't start

[Brian29]

You had dash apart looking at connections? As my dad would say, go back to the last thing you screwed with. Worked fine before that, Yes?

[katy]

When the points are closed, the secondary circuit sends high voltage from coil to distributor.

Close, but no cigar.

When the points close, the coil "charges up", when the points open the coil discharges and creates the high voltage which gives the spark at the end of the coil wire or at the spark plug when the engine is running. That's why there's 4 lobes on the distributor cam, one for each cylinder in turn.

[GAR64]

The video was excellent. Thanks. I tested the ignition switch. 6 volts at the red wire with key off. Turned on key and only saw about 0.5 volts at armored cable side. Also checked red wire again with key on and saw nothing. Bad switch right?

[Mitch//pa]

We're the points closed? If so open them and retest...use a credit card or such

[GAR64]

Why would that matter if I'm just testing at the ignition switch?

[Mitch//pa]

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If the points are closed then it grounds the circuit.... With the key on it will show a ground all the way to the coil points closed.... With the key off it will only show the ground to the armored cable side of the switch points closed

[GAR64]

Ok. So if the points are closed, the switch my be fine. I am now betting there is an issue with the points. Going to check now.

[Mitch//pa]

I would open the points and see if you get 6v to the moveable point arm with the key on

[Mitch//pa]

If so then short across the points with a screwdriver .. Each time you short the points it should spark out the coil wire to a head nut. Key on

[Willie Krash]

For me if it is a no spark issue take a test light, ground one side and clip the lead to the coils point side. Put the secondary wire close to the head. Turn the key on...
Push the starter rod down and watch the test light. It "has" to go on and off.
If so electrically you have what you need for spark.
If the light just stays on your points are open, if it stays off they are grounded.
On my car the dist. side of the coil is on the driver side.
Some times knowing what is okay and works leads you to what doesn't work. This simple test eliminates a lot of guess work.

[Patrick L.]

Originally Posted by GAR64

Why would that matter if I'm just testing at the ignition switch?

post #9

[GAR64]

Willie, you are confusing me. I made sure the points were opened by putting a plastic card in. With key on, I see 2 volts on both sides of ignition switch which made no sense so I checked voltage at end of armored cable at distributor end which showed 6 volts. I would think that says switch ok. So if voltage is entering distributor, what would I check next?

[BILL WILLIAMSON]

The WIRING diagram is easier to read than a ROAD MAP---------
Bill W.

[Sunnybrook Farm]

If you want to check the switch for sure, just take the wires off and clip them together and see if it will start. If the points are open in the dist then you shouldn't get any reading on any metal such as the upper plate, if you can get any thing then they are grounding somewhere like the cam or that wire from the lower plate. It is confusing though simple once you get a handle on it.

[Mitch//pa]

Are you using your meter correctly ?? The 6v has to come from the coil via the ignition switch to get to the points... Try a testlight

[Patrick L.]

Last time. Posts #3 and #9. Others have said the same as in them.

[Willie Krash]

Originally Posted by GAR64

Willie, you are confusing me. I made sure the points were opened by putting a plastic card in. With key on, I see 2 volts on both sides of ignition switch which made no sense so I checked voltage at end of armored cable at distributor end which showed 6 volts. I would think that says switch ok. So if voltage is entering distributor, what would I check next?

If you do it my way you you know all of that is okay (or not). The light going on and off is really showing you the points are getting juice. When the light comes on the points are open, when it goes off the points are closed, that means they are working.
Now if you crank the engine over and hold the coil wire next to the head and get no spark, you conclude the points are okay as well as the juice you need.
You can take the key, battery, points issue and set it aside. Condenser, coil and the coil wire can be checked.
Just keep eliminating components.
A new component that is un-necessarily replaced will compound your troubles.

The simple explanation is when the points are closed the coil is being saturated. When they open one field collapses over the second winding (within the coil) producing the 18KV you need to fire the plug. The points close and it starts again...All of that high voltage is at the tower and through that big coil wire. It should throw a spark to the head when you position it a 1/4 inch or so away, as was mentioned.
As an example if it does throw a spark. pull a plug out and lay it on the head and turn her over and see if it fires. Or have your wife hang on to it while you crank the motor. This only works one time.
Now if the plug doesn't fire but the coil wire will produce a spark you have narrowed this problem down.

[Willie Krash]

Regarding volt meters, it takes 30 seconds to hook up a test light as I have described.
Does the light light on both sides of the coil? yes...
Hook up to the dist side and turn the key on...turn the motor over.
IF the light goes on and off (key on) you know the key is working and the points are....all this in under 60 seconds.

[GAR64]

I apologize if it appears I am not listening. I read posts 3 and 9 again. I have voltage at the wire entering distributor. Nothing at the points when open. Apparently, the problem is in distributor. I will get help here. Thanks for all of your time.

[Tom Wesenberg]

Originally Posted by GAR64

I apologize if it appears I am not listening. I read posts 3 and 9 again. I have voltage at the wire entering distributor. Nothing at the points when open. Apparently, the problem is in distributor. I will get help here. Thanks for all of your time.

From what you just said, I'd say you have a lower plate to points wire shorting to ground. Usually this means the cable is screwed in too far or the terminal at the points nut is hitting ground.

Mike made a very good point about the test light being quick and checking a lot of the circuit at once.