Help needed from the electrical experts

Bob/Kansas City

Bob/Kansas City

Senior Member
Sorry for the lengthy post but my frustration is mounting with this ignition problem.

Restoration continues on my early '31 roadster. It's now to the point of first start up on all new ignition system and wiring. The problem I'm having is that I can't get spark to the distributor.
Here's what I have done:

Completely rebuilt distributor - new top and bottom plates, wire between the two, new points set to .018" , new condenser, cap, rotor and body.
I have rechecked to be sure the wire between lower and upper plates is not grounding out.

New plugs all gapped to .023"

New coil mounted with plus terminal to the passenger side

New coil to dist wire.

New ammeter

New 6 volt battery - checks 6.4 volts with multimeter after cranking engine over for a while to try starting.

New Randy Gross 6 volt pos ground alternator

Timing set and rechecked in accordance to Marco's site info

Repro ignition switch and cable from Bratton's. I have screwed the cable into the distributor only about 3 turns so it won't short out.

All new wiring through out: I've wired the car in accordance with Les Andrew's info in the red book.

Black/yellow wire from single wire alternator to drivers side of terminal box then on to charge side of ammeter through new dash wire.

Yellow wire in middle of loom to the fuse at the starter then on to passenger side of terminal box and then on to discharge side of the ammeter through new dash wire.

Short black wire from Negative side of coil to drivers side of terminal box.

Red wire from Positive side of coil to ignition switch.

I've spent hours tracing, checking and rechecking wiring etc. Also have been using the excellent no spark troubleshooting procedure that I found by Mike V Florida but so far have been unable to locate the problem.

I'm beginning to suspect that the repro ignition switch is bad. This is a two pole switch from Bratton's unlike an original pop out switch with the one pole for the red wire.
Can anyone tell me if it makes a difference as to which terminal on the switch the red and black wires go to? The black wire is the one from the armored cable from distributor. Is there a way I can test this switch to see if that is the problem?

Finally can anyone see if they can spot any mistakes I might have made in wiring? Here's a couple of pics - pardon the dust. Mechanical work was completed last winter while body work was being done over the summer so it's been sitting for a while.

Any constructive help or comments would sure be appreciated !
Bob
 

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Before doing anything remove the dash from the tank. Let it hang

Key off what do you have for power at both igniton coil posts?
PM me if you wish
 
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Not trying to be a smart a$$ but did you check your fuse?

A switch is easily checked with a Ohm meter. or simply by with a jumper wire between the switch terminals.
 
Looks like you have it all wired correctly but you don't mention if you have 6v <> at all the connections in the circuit. You can use the following step by step trouble shooting with a multi meter or a test light. Good luck,
Al
​
This writ-up is intended to help the Model "A" operator whose car has stopped on the road.

For this writ-up we will assume that you have done a quick check to determine fuel is reaching the carburetor.

Quick Ignition Check---
Use a business card between the points to hold them open, and turn the key on.
Using your test light, or multi meter determine that you have power at the moveable points arm and both sides of the coil and both terminal box terminals.
If you're not getting power to the moveable point arm the problem lies between the switch and the points, via armored cable, or the distributor pigtail, or the fuse or other connections.

With the points closed business card removed, key on you should lose power at the moveable arm and one side of the coil. (the points closed makes a ground) if you don't lose power clean the points contacts so they make a ground.
Hold the high voltage wire from the coil about 1/8" from a ground. With points closed and key on open and close the movable points arm and look for the spark.

Note:
Each time the points close they send the ground to the coil so it can build up a good magnetic field. As soon as the points open this high voltage is sent through the heavy wire to the distributor.

Step by Step Check of the Ignition Circuit Wiring:
• Yellow wire connected from post on starter switch (or fuse) to terminal box post (post on passenger side of terminal box).
• Ammeter (-) side connects to passenger side post on terminal box.
• Ammeter (+) side connects to driver side post on terminal box.
• Black wire connects from driver side post on terminal box to coil (-) terminal.
• Red wire connects from coil (+) terminal to ignition switch.
• Yellow/Black wire also connects from driver side terminal box post to the cut out terminal. That completes the ignition wiring except for the ignition cable and distributor plate.

•Here is a voltage check of the circuit:
• Connect the (+) side of your volt meter to a good ground point on the engine or frame.
• Touch the (-) probe to the passenger side terminal box wing nut. Read 6 volts.
• Touch the probe to the driver side terminal box wing nut. Read 6 volts.
• Touch the probe to the (-) terminal on coil. Read 6 volts.
• Touch the probe to the (+) terminal on coil. Read 6 volts. (with points open)
• Touch the probe to the end of the moveable points arm, read 6 volts. (with points open)

• NOW TURN IGNITION KEY ON.
• Remove business card from between points. Open and close points and look for spark each time points open, (no spark means bad condenser, replace condenser).


• If points are sparking then disconnect the coil center (high tension wire) from the distributor cap (leave connected at coil end). Place the free end of the coil wire about 1/8" from one of the
engine head nuts. Crank the engine over (or open and close the points manually) with the ignition key on. There should be a bright blue arc from the coil wire to the head nut (ground point). No arc means bad coil.

Having said all of that, there are several things to check for:
New condensers can go bad and new coils can go bad. But first look for something that may be shorting the circuit or causing an open in the circuit.
Some of the other things to check are:
Bad Ammeter. If ammeter has open circuit, all voltage is lost to the coil.
Possibly a burned wire because of loose connections on the back of the ammeter,
A missing rubber grommet through center of terminal box, causing the ignition cable to short against terminal box posts or firewall, causing large current draw to burn wires.
Do not screw ignition cable into the distributor too far. It can short out if screwed in too far. Make sure all nuts on the terminal box posts are tight.
Also the two rivets on the bottom distributor plate sometimes get loose (especially on the reproduction plate) and short out the bracket it attaches.
Make sure the terminal studs haven't back out to short to the fire wall.
Get into the habit of cleaning both sides of all electrical connections.
Use a light grease on all connections to prevent corrosion.

Much of this information comes from Les Andrews, a member of MAFCA, 1998 Technical Director
 
im going to assume your red wire in your coil/terminal box picture is actually connected to the coil - i just dont see the nut like on the drivers side.
 
Start with the easy checks first. Since this is wired correctly as a 1931, the coil current will show on the ammeter. Does the ammeter bounce back and forth as the engine is cranked with the key ON?
It should if the points are working and the voltage is reaching them, and the distributor has a good ground.
If not, then pull the panel forward and measure voltage on the two switch terminals as Mitch said.
Until we hear what you find with this we are only guessing where to check.
 
you will have to set your spark plug gap to .035 instead of .023
once you get it figured out
 
I hate to toss it out because I still feel like an idiot, but I turned my pop-out into the distributor housing too far and wound up shorting it out internally - are you sure this is OK?
 
OK - did some tests as recommended. Here is what I find:

Mitch//PA - with dash hanging, key off I am getting about 6.3 to 6.4 to both coil posts. Also get same reading with key on.

Y-Blockhead - Yes checked fuse and it's good. You're right - Sometimes it can be the simplest things.

SeaSlugs - Yes red wire is firmly attached to pos post on coil .

MOT - Spark plug gap was a typo... they are .032 not .023 but thank you.

Tom W. - when cranking with key on and dash hanging loose the ammeter needle does not bounce. Just holds steady showing slight discharge.
When the key is turned on but nothing else is done the ammeter shows a slight discharge. No headlights, tail lights, cowl lights or horn are wired in at this time so we can rule those out.
When checking ign switch terminals with key off I have 6.4 v at red wire and o at black wire. With key on I have 6.4 at both switch terminals.
Does this indicate that the current is not reaching the points?

I will be out for a while this afternoon but will check back later for more and will do more tests as necessary.
Bob
 
Leave dash hanging.
Key on points open you should have 6v to moveable point arm....
Points closed you should lose the 6v at the point arm and at the red wire of the coil...
If you do not lose the 6v at the point arm (points closed)ck the points contacts maybe they are oxidized from sitting in the box even though they are new.
If all tests good you should get a spark from the points when opening and closing them manually key on... At the same time it should spark out the coil wire if held near a head nut.
As you open and close the points key on the red wire should also flash power on and off... This is what collapses the field to induce a spark from the coil
 
Mitch//PA - Here's what I got for further test results...Just in case of corrosion I did clean the points with a bit of sandpaper and blew out any grit.

With the dash hanging, Key on and points open I do not get voltage at points arm. I do have 6 v at red wire on coil.

Points closed and key on no voltage at point arm but still have 6v at red wire at coil.

Key on, points closed and manually opening and closing points does not produce any spark.

Does this indicate a bad ignition switch cable to distributor?
 
Key on points open you should have power at the red wire on coil, both terminals at the ignition switch... If you have that and still no power at the moveable point arm your trouble is between the armored cable to the point arm.... Remove the upper plate and do some power checks. From the end of the cable through to the lower plate wire to the points arm..
Common issues are cable screwed in to far, lower wire contact flag rubbing the dist housing or rubbing on internal components...

Think of it as one long piece of string that the juice has to go through, from the red wire connector at the coil to the moveable point arm. In between is the distributor, armored cable and igntion switch.... Just find out where it's grounding out or losing contact using your meter...

I would think your losing contact because if it was grounding out that would show all the way back to the ignition switch / coil terminal
 
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Mitch is right on here . This is where learning how to use a volt ohm meter can help you pinpoint in less than 5 minutes . My bet is also one internal to the distributor as Mitch said .
You can try unscrewing the ignition cable a few turns and see if you get voltage.
Larry
 
Bob/Kansas City said:
Mitch//PA - Here's what I got for further test results...Just in case of corrosion I did clean the points with a bit of sandpaper and blew out any grit.

With the dash hanging, Key on and points open I do not get voltage at points arm. I do have 6 v at red wire on coil.

Points closed and key on no voltage at point arm but still have 6v at red wire at coil.

Key on, points closed and manually opening and closing points does not produce any spark.

Does this indicate a bad ignition switch cable to distributor?
Click to expand...


Rereading your post with the key on points open (KOPO) are you getting power through the aftermarket ignition switch????
Check both wires off the ign switch probing into the wire itself will eliminate a break in the eye connector
 
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Mitch//pa said:
Rereading your post with the key on points open (KOPO) are you getting power through the aftermarket ignition switch????
Check both wires off the ign switch probing into the wire itself will eliminate a break in the eye connector
Click to expand...

Mitch
By probing the wires I get the following:

Black wire with key on I get .3 volts. with key off I get no voltage

Red wire with key on I get .46 volts and with key off I get 6.4 volts.

I have been wondering if this switch is good or not.

Bob
 
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