no start

nkaminar said:
If you are not getting the bouncing needle then the points are not switching on and off. Here is what to look for:


  • The points should be shinny and clean and gapped correctly.
  • The stationary point has to have a good ground. Is there paint under it or another reason it is not grounded?
  • The distributor has to be grounded. Some people will run a wire from the grounded side of the condensor to a grounded point on the engine.
  • There has to be good electrical conductivity to the moving point. With the points open or a piece of cardboard between them and ignition on, measure the voltage at the moving point while you wiggle wires from the starter motor terminal all the way to the points.
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I should have a chance (I pray to...) look at all of this today. Thanks so much!
 
Put a jumper wire across the the terminal of the junction box. That eliminated any possibility the ammeter may be bad. See what happens.
 
Here's where I am today.
Checked every wire. All tight, all clean. 6.2v. at all points.
Installed a modern ignition switch. Hot at both terminals when "on". 6.2v.
Disassembled distributor. Beautiful inside. No grounding out. No frayed wire. Beautiful.
Bypassed amp gauge.
Tested coil. Great spark.

Try to start? Nadda.
Reconnected amp gauge. No needle wobble when trying to start.

You guys have been super helpful. Please rest assured I have a pretty darn good grasp of auto mechanics.
Fairly new to Model A stuff but still, this shouldn't be so difficult.
 
How about post # 35??? You won't see a negative twitch when cranking unless your car has the service bulletin applied.

Do you have a safety fuse in your system? The one down by the starter? On some of those fuse holders, the end rivets work loose and can allow an intermittent failure. Do the lights or horn work when the car won't start?

6.20 volts is about 1/2 charge on the battery, if I recall. A hydrometer can test your battery's state of charge without removing the battery from the car.
 
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Rob Doe said:
How about post # 35??? You won't see a negative twitch when cranking unless your car has the service bulletin applied.

Do you have a safety fuse in your system? The one down by the starter? On some of those fuse holders, the end rivets work loose and can allow an intermittent failure. Do the lights or horn work when the car won't start?

6.20 volts is about 1/2 charge on the battery, if I recall. A hydrometer can test your battery's state of charge without removing the battery from the car.
Click to expand...

No fuse.
Lights and horn always work regardless of starting.
By the way, it did start a few days ago a number of times. Then it didn't.
6.3v is full charge. It cranks quite well.

I do not have access to the service bulletins. Might you offer a sketch or explanation?
 
On a stock Model A, the black wire to the - negative post of the coil supplies power to the primary windings and the red wire runs to the ignition switch and on to the distributor.

Prior to November, 1929, the black wire to the - negative coil post was sourced on the passenger side of the terminal box. (The side with the solid yellow wires) Move this connection to the driver's side terminal post. (The side with the yellow with black stripe wires from the generator / alternator)

This allows the opening and closing of the points to be seen on the ammeter as the engine is being cranked, and when at very low idle speeds also. It is a slight neg, twitch of approximately 4 amps.
 
Once you have the wires hooked correctly by the bulletin, If you block your points open / insulate them with a business card or folded paper, turn the ig key on. Without cranking the engine, if your ammeter shows a steady negative draw, you have an unintended ground somewhere between the + positive coil post and the points arm. (nothing else is on, brake lights, etc.)

Turn the ig key off, if the draw remains, the issue is between the + positive coil post and the switch or the switch is not opening the circuit, which is not likely with your new switch. If the draw ceases, the ground is between the switch and the points arm.
 
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Rob Doe said:
Once you have the wires hooked correctly by the bulletin, If you block your points open / insulate them with a business card or folded paper, turn the ig key on. Without cranking the engine, if your ammeter shows a steady negative draw, you have an unintended ground somewhere between the + positive coil post and the points arm. (nothing else is on, brake lights, etc.)

Turn the ig key off, if the draw remains, the issue is between the + positive coil post and the switch or the switch is not opening the circuit, which is not likely with your new switch. If the draw ceases, the ground is between the switch and the points arm.
Click to expand...

You're a ton of help and thanks for putting it on a level I understand. As time allows, I'll double check everything. Turns out I do have a reprint of the bulletins. I'm gonna go through them tonight :)

Thanks again. I do appreciate the advice and help.
 
Kube said:
So, if the ammeter is defective, the car won't start?
Click to expand...

In most cases that is correct. In Dec 29 Henry moved the the ignition wire to the other side of the terminal box. This is why you can see the slight deflection of the ammeter when the engine is cranking over. Lots of people with 28/29 A's have moved this wire to this position. The one problem is that a faulty ammeter will cause ignition problems.
 
The one class I had some trouble with during my aviation mechanics training was basic electricity. I did OK in the theory part which was partly in the mathematics courses to understand AC circuits and wave lengths and the like. Where I had problems was in the practical part where we had to build circuits on a peg board. They docked points for anytime a person blew a fuse. With those mistakes behind me, I took it very seriously after that. As a young boy on the farm, I checked everything with a test light. In most cases this works fine but I learned later that knowing a circuit has continuity is only part of the situation. Knowing the resistance of a circuit is the other part. Higher than normal resistance is a sign of a weak pipeline for the current to flow through so to speak. The Ohm meter is by far the best way to test circuits. A test light can be deceiving at times. An Ohms meter will tell you if you have simple things like a good clean ground path back to the battery. Just make sure nothing in the dash comes too close to the gas tank. If in doubt, insulate it from any possible contact.

In electrical troubleshooting, an intermittent problem is the hardest to find. Anything that can move like the little short jumper in the distributor may need to be tested while moving the spark control lever to see if it has an open caused by movement. The wire from the ignition switch to the distributor can move a bit under certain circumstances so it has to be wiggled while checking to see if it is a problem with a wire or a funky connection at a terminal joint due to cold solder, wire breakage, or a crimped terminal connection that is not tight enough.

Heat related problems with coils and condensers have to be checked with equipment that can work cold or hot or the part has to be changed out with a known to be good component.

I check the spark at the plugs on ignition systems to make sure it's got spark. If no spark then there is something in that ignition circuit that is faulty. If it has good spark, then it's time to look at the engine for compression or the fuel system for proper delivery. They say to always check the easy stuff first but sometimes, it ain't the easy stuff that's problematic.

An ammeter is part of the pathway between the battery and the generator and loads. It should pass an Ohm meter check and it can be tested by being in line with any circuit from a battery to a load or to a battery charger. These modern reproductions leave a lot to be desired but they will work. I would ditch the finger tightened nuts and put some standard nuts with lock washers on there. Nobody looks back there anyway.
 
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