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Old 09-25-2020, 05:47 PM   #21
shew01
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Default Re: Car Will Not Start--No Apparent Spark

I have 6 volts on the movable point arm and the stationary point arm.




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Old 09-25-2020, 05:50 PM   #22
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Default Re: Car Will Not Start--No Apparent Spark

Quote:
Originally Posted by 700rpm View Post
Check your pigtail in the dissy.

If that wire is shorting out, would that explain 6 volts being on both point arms? If I check the wire, Iíll have to retime the car. I have never timed a Model A, and I would like to avoid introducing yet another variable in the starting process.

Could anything else explain 6 volts on both point arms? Maybe the rebuilt pop out ignition switch?


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Old 09-25-2020, 05:57 PM   #23
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Default Car Will Not Start--No Apparent Spark

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Originally Posted by Patrick L. View Post
What WMWS said.
If there is power to the open point arm then there is power to both sides of the coil and thru the terminal block.
It doesn't sound as though you checked the points closed for no power. Clean the point contacts and check that the distributor set screw and jam nut is/are snug.

I think I posted earlier that both sides of the coil have power. I checked again, and I see 6 volts on both sides of the coil.

The driver side of the junction box gets 6 volts. The passenger side gets 0 volts. Putting a temporary jumper across the junction box studs reduces the voltage to near 0.

I checked the jam nut, and itís tight. I donít see the correlation of the jam nut to not having spark.

Last edited by shew01; 09-25-2020 at 06:16 PM.
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Old 09-25-2020, 06:20 PM   #24
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Default Re: Car Will Not Start--No Apparent Spark

If the points are closed and the ignition is on you will not get voltage on the switch side of the coil.

Last edited by wmws; 09-26-2020 at 07:24 AM.
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Old 09-25-2020, 06:29 PM   #25
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Default Re: Car Will Not Start--No Apparent Spark

Are you getting 6 volts on both sides of the points with the points open. If so that is really weird. It could be that the end of the pigtail wire is grounding out on the upper plate and at the same time the distributer is not making ground with the block.
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Old 09-25-2020, 06:34 PM   #26
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Default Re: Car Will Not Start--No Apparent Spark

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When the points are closed there should be no voltage to them because they are supposed to be grounded. The set screw helps with that ground. Somehow you are getting voltage to the stationary point block when you shouldn't. Voltage is either traveling thru the the primary lead [ short to distributor body from a bad cable or being screwed in too far, etc] or there is no path for a ground from distributor body, upper plate, to cylinder head. The set screw and jam nut are part of a ground.
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Old 09-25-2020, 06:36 PM   #27
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Default Re: Car Will Not Start--No Apparent Spark

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Originally Posted by wmws View Post
If the points are closed and the ignition is on you will not get voltage on the switch side of the junction box. So all sounds normal.
I used a point file earlier to touch up the face of the points. A moment ago, I used a new $20 bill. That will have to do. It didn't start.
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Old 09-25-2020, 06:42 PM   #28
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Default Re: Car Will Not Start--No Apparent Spark

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Originally Posted by wmws View Post
Are you getting 6 volts on both sides of the points with the points open. If so that is really weird. It could be that the end of the pigtail wire is grounding out on the upper plate and at the same time the distributer is not making ground with the block.
Yes, I get 6 volts on both sides of the points with with points open. The pigtail wire sounds plausible. I just hate to foul up the timing to check it.
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Old 09-25-2020, 06:43 PM   #29
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Default Re: Car Will Not Start--No Apparent Spark

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Originally Posted by Patrick L. View Post
When the points are closed there should be no voltage to them because they are supposed to be grounded. The set screw helps with that ground. Somehow you are getting voltage to the stationary point block when you shouldn't. Voltage is either traveling thru the the primary lead [ short to distributor body from a bad cable or being screwed in too far, etc] or there is no path for a ground from distributor body, upper plate, to cylinder head. The set screw and jam nut are part of a ground.
>>The set screw helps with that ground.

Good point. I hadn't thought about that.
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Old 09-25-2020, 07:39 PM   #30
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Default Re: Car Will Not Start--No Apparent Spark

A couple of weeks ago I had a road side break down! This may not apply to your situation,but have you check to see if the rotor is turning while you are cranking.Mine was not originally I thought is was my time gear but my shaft at the bottom of the distributor actually rusted away and that was the reason my distributor was not turning, and points not operating. Timing a model a is really nothing to worry about.Jack Baham who post on this site has a excellent YouTube video that shows you a easy full proof method
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Old 09-25-2020, 09:45 PM   #31
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Default Re: Car Will Not Start--No Apparent Spark

It's time to tear into it and figure it out.

The diagram you posted will allow you to Hot Wire your ignition. In order to do that you will need to remove the distributor and the armored cable.

Don't be concerned about the timing... it won't be affected at all. Loosen the jam nut and screw, and lift the distributor out. The tabs on the shafts are offset so you wont get it out of time and won't introduce another unknown.

Start by bypassing the ignition switch as shown on the wiring diagram and try to start it. If it starts with it Hot Wired you've solved the problem. But be aware that with no ignition switch you will need to shut off the gas or choke it out to stop it.

I find it hard to believe that your distributor isn't grounded, but having voltage on the stationary point makes no sense.... But when you pull that distributor out, look at the surfaces and be sure they are clean... also check the screw and jam nut area.
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Old 09-25-2020, 09:46 PM   #32
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Default Re: Car Will Not Start--No Apparent Spark

Iím not sure where you are in this process but hopefully you have resolved the issue. I can only say that my similar issue was the fuse. It did not show signs of being blown but I replaced it and all was good. My visual inspection failed me in this instance. Good luck.
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Old 09-25-2020, 10:13 PM   #33
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Default Re: Car Will Not Start--No Apparent Spark

It sounds to me like you are way overthinking the problem. I don’t know about volts here or volts there. This is a simple car, and I’m just a shade tree mechanic. But I have played with and worked on these cars for over 55 years, so I have some experience. Timing your A is a basic function and a necessary skill if you own a Model A. No need to be afraid of it. It takes maybe 10-15 minutes. It’s worth it just to know if the pigtail is shorting out (which it often does).

I suggest: Pull the distributor, disconnect your ignition cable, and turn the key on. Then scratch the end the cable on a head nut. If you have spark, you have current going into the dissy. Shut off the ign. Put the cable back in. (But not too far). Check the pigtail. No contact with the body (so no short)? Reassemble. Replace the dissy in the head. Turn the ign. on. Open and close your points. You should get a spark at the points. If not make sure you have the proper insulating washer under the point block. If you have spark at the points, reset the timing. Check for spark at the points again. If you have it, you’re good. The basic requirements to making a Model A start are fuel, spark (ignition) and timing. With those, and fundamental clearances and settings, the car should start.
Your car was running OK before this problem. Mike V’s and other suggestions are valid, but do the easy things first. The answer should be simple.
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Last edited by 700rpm; 09-25-2020 at 10:48 PM.
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Old 09-25-2020, 10:19 PM   #34
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Default Re: Car Will Not Start--No Apparent Spark

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Originally Posted by wmws View Post
If the points are closed and the ignition is on you will not get voltage on the switch side of the junction box. So all sounds normal.

Not sure I understand this, what does the switch have to do with the
junction box.
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Old 09-26-2020, 06:37 AM   #35
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Default Re: Car Will Not Start--No Apparent Spark

Quote:
Originally Posted by jm29henry View Post
A couple of weeks ago I had a road side break down! This may not apply to your situation,but have you check to see if the rotor is turning while you are cranking.Mine was not originally I thought is was my time gear but my shaft at the bottom of the distributor actually rusted away and that was the reason my distributor was not turning, and points not operating. Timing a model a is really nothing to worry about.Jack Baham who post on this site has a excellent YouTube video that shows you a easy full proof method

I checked. The rotor turns as the engine cranks.


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Old 09-26-2020, 07:14 AM   #36
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Default Re: Car Will Not Start--No Apparent Spark

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Originally Posted by capndan77 View Post
Iím not sure where you are in this process but hopefully you have resolved the issue. I can only say that my similar issue was the fuse. It did not show signs of being blown but I replaced it and all was good. My visual inspection failed me in this instance. Good luck.

Thanks for posting. Earlier, I checked, and I had headlights and horn. Now, I donít. So, I may have a couple of problems.


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Old 09-26-2020, 07:22 AM   #37
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Default Re: Car Will Not Start--No Apparent Spark

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Not sure I understand this, what does the switch have to do with the
junction box.
You are correct. I meant to say the switch side of the coil. I will correct that in the post.
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Old 09-26-2020, 07:44 AM   #38
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Default Re: Car Will Not Start--No Apparent Spark

The fuse is good. When removed and held to negative battery terminal, the multimeter gets 6 volts to the positive battery terminal (through the fuse).

With the ignition switch on (popped out) and the fuse removed, I get 6 volts to flywheel side of fuse holder and 0 volts to the radiator side of the fuse holder as expected. I also get 6 volts to both sides of the coil and 6 volts to both junction box studs. The movable point arm has 6 volts, and the stationary point arm gets 6 volts, which doesnít sound right.

With the ignition on and the fuse in place, I see the following changes. I donít see any voltage on either end of the fuse (while inserted into its holder), and the passenger side junction box stud drops to 0 volts. All of the other cited measurements are the same.


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Old 09-26-2020, 07:57 AM   #39
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Default Re: Car Will Not Start--No Apparent Spark

Quote:
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Not sure I understand this, what does the switch have to do with the
junction box.




The power has to come from somewhere. It comes from the junction box.
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Old 09-26-2020, 07:58 AM   #40
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Default Re: Car Will Not Start--No Apparent Spark

Something is very wrong if you are getting voltage to the junction box and coil with the fuse removed. Are you sure your fuse is hooked up correctly.
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