'31 roadster-NO SPARK from Coil!!!

[Tex]

Guys,

I drove my '31 roadster around to the shop today to test the new carb and it ran great. I pulled up the front on my shop and shut if off to open the garage door.

I went back to start it (when it is warmed up it is easy to start) and it just cranks??? I double checked that I had the key on and all the basics.

So I get the test light out and start checking.
-power to the coil both sides-key off
-Power to two screws on the junction box-key off
-power to the points-key on.
-power to starter-engine cranks
-no power from coil to distributor cap/ plugs
-no power from coil wire to distributor cap.


Ok, maybe the coil died all of the sudden, so I went over to my Model A coupe and pulled the coil off it and still no spark from the coil into the distributor.

Did I get two bad coils??? The coil that was on it was brand new and worked great.

What am I missing??


Thanks for your help in advance.

Tex

[Brentwood Bob]

Check for broken wire from upper plate to lower plate. Bob

[Chuck Sea/Tac]

I don't know, but would a bad condenser cause those symptoms?
Chuck

[1931 flamingo]

I go with Brentwood Bob. Let us know what u find, please.
Paul in CT

[Tex]

Originally Posted by Brentwood Bob

Check for broken wire from upper plate to lower plate. Bob

Excuse my ignorance, but what is upper plate/lower plate?

It is a brand new cloth factory wiring loom installed by Bert's Model A........If I a have power to the coil, but not out of the coil is it another bad coil???

[wardkew]

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Inside the distributor, there are two plates, the upper which has the points on it, and below that is the lower, which is connected to the armor cable from the ignition. There is a wire that connects the two plates. I had the exact same thing happen to me, and found that the wire shorted out.

[Tex]

Originally Posted by wardkew

Inside the distributor, there are two plates, the upper which has the points on it, and below that is the lower, which is connected to the armor cable from the ignition. There is a wire that connects the two plates. I had the exact same thing happen to me, and found that the wire shorted out.

Would a broken wire or bad condenser still show power at the points with a test light?

Sorry again for the ignorance I am learning model A's for the first time.

[Tom Wesenberg]

I would suspect the points may need to be cleaned. I would sand or use a points file on the contacts, then try it for spark. I have a motorbike that when I first started riding it I had to remove the flywheel about a dozen times in a couple days to sand the points for a good spark. It's been fine for over 10 years now, except for one time a few years ago It just died during a 20 mile ride. I had to remove the flywheel and sand the points and was on my way again. My Model A has been flawless, except for one time about 2 years ago. I was turning right and the engine died as though I'd turned off the key. I sanded the points and was on my way again.

To check for dirty points:
You can stop the engine with the points open, then turn the key on and short across the points contacts with a screwdriver. Hold the coil wire 1/4" from a head bolt and check for a good spark. If you have a good spark, then sand the points, crank the engine and check for spark. Sometimes you need to sand a few times to get a good spark.

[newshirt]

Here's a possibility...

Put a test light (or voltmeter) on the breaker point arm. The light should turn on and off when the points open and close. If not, check for a short circuit against the side of the distributor wall.

The pigtail wire on upper plate can short out when tightened down.

Light always on? Points aren't closing.
Light always off? Points are shorted to ground. Maybe pigtail is shorted.

[Mike V. Florida]

My vote is dirty points. I this may help if you or others do not already have this.

[RonC]

An engine only needs 3 things to run, gas, spark and air. Your engine was just running so realistically you should first determine if it’s a spark or gas problem. In EVERY CASE, the first thing you do is watch your ammeter needle while you’re cranking the starter to see if it moves (bounces). If the needle bounces you more than likely have a fuel delivery problem however there is an outside chance your coil just quit. If your needle does not bounce then you have a spark problem inside your distributor or ignition circuit. Does your needle bounce??

[IrishHills]

The way I check the coil is .. turn engine until points are closed, then pull coil wire out of cap, hold it close to a ground (1/4"), then with your thumb open and close points, with key on you should have a nice blue spark every time you open and close, up to 1/2".

[Jerry Parr WI]

What are the cranking voltages doing. Connect your volt meter from the distributor side of the coil to ground and crank the engine. The voltage should swing from 6v to 0 as the points open and close. If so the points are ok and you have power to the coil. You can also see this on the ammeter.

[Tex]

Originally Posted by IrishHills

The way I check the coil is .. turn engine until points are closed, then pull coil wire out of cap, hold it close to a ground (1/4"), then with your thumb open and close points, with key on you should have a nice blue spark every time you open and close, up to 1/2".

I put the test light into the coil wire end and cranked the engine and nothing came out.......That is why I assumed it was the coil until I swapped another one in and still nothing out of the coil.

I am begining to think my problem is the condenser or the wire between the plates. I will investigate when I get home tonight and let you what I find.

Thanks for your help so far........I am sure we can figure it out.

[Jason in TX]

Also, a quick look is pulling the dash panel off. Just 4 screws to make sure no wires came loose or are touching the gas tank grounding out. (disconnect battery or you may see sparks.)

I've also heard of cheap-o ammeters going bad, which would be a break in the circuit. You could check continuity across the two posts to ensure it's ok. (Put on ohms setting on a tester and the needle will jump and peg out on the other side or no resistance.)

Think of the electricity like a path. Walk down the path and look for anything that could break that path.

[Tom Wesenberg]

Originally Posted by Tex

I put the test light into the coil wire end and cranked the engine and nothing came out.......That is why I assumed it was the coil until I swapped another one in and still nothing out of the coil.

I am begining to think my problem is the condenser or the wire between the plates. I will investigate when I get home tonight and let you what I find.

Thanks for your help so far........I am sure we can figure it out.

Where is "OUT of the coil"? If you mean you are trying to light the test light from the high tension coil wire terminal, then it ain't going to happen, (other than a neon bulb).

With the points open, touch the test light to each of the two primary coil terminals and the test light should light on each one(the clip lead is grounded of course).

With the points closed, the test light should light on one primary coil terminal and not on the other one. The key is on of course for these tests. If the light still lights on both terminals, then you have an open somewhere between the coil and points. It might be a bad switch or dirty points, or broken wire.

[Ed Saniewski]

Tex, did you find the problem?

[Tex]

Originally Posted by Ed Saniewski

Tex, did you find the problem?

Yes, I got it running last night. I had already sanded the points, but I guess I did not do a good enough job.

Last night I took the distributor cap off and sanded the points really good and it started.

I think part of problem is the engine is so worn out that the compression is low and it makes it hard to start anyways combined that with dirty points-NO SPARK.

Thanks for all your help and advice.......Now does anyone have a good used engine forsale???

[Mike V. Florida]

If the points were badly pited and not that old then change the condensor as this also keeps the spark reduced when the points open.