1951 8ba no spark

[jltrade]

Car was running fine. Making a left hand turn from traffic stop car died when i hit second gear. Carb has fuel and I tried ether to capitalize on even weak spark. Still no luck. Have power to coil, but no spark from coil wire. Changed points (no new condenser handy). Unplugged overdrive, still no spark.

I will pick up a couple of condensers today, but has anyone had an ignition coil fail completely without warning?

[BUBBAS IGNITION]

The loadamatic vacuum distributor has a concealed lead wire under the distributor. Unhook primary feed from contacts and inspect as good as you can see. I would then use a ohm meter to check for continuity from contact lead to ground ( shouldnt be any) .

[oldford2]

That wire Bubba is talking about flexes with the vacuum advance so it is common for it to wear a bare spot and ground out from time too time. If it has a worn spot, replace it, don't use shrink wrap to fix it. Too stiff and won't allow the advance. Don't ask me how I know.
John

[BUBBAS IGNITION]

Good tip John!!!
We use a lead wire and make up a new lead.
Get them in all the time with hard plastic heat shrink, blocks the action of the vacuum advance.........

[jltrade]

I've replaced everything, one part at a time: points, primary wire, condenser, cap, rotor, coil, coil wire. No spark. Have 6.3 volts at coil and confirmed that braided copper wire at points is grounded. I've turned fan by hand to verify distributor shaft turns with crank, and it does. Symptoms lead me to believe that coil is somehow grounded all of the time. Is there anything else that can go wrong systemically within the distributor?

[George/Maine]

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Put your meter on the OHMS scale touch together x1 scale. test ok touching together.
remove coil points wire from coil. Take condenser screw and let condenser not touch anything. Ground meter wire and other end to points wire.
Turn engine over should see meter make and brake.
The points wire under to points doesn't want to touch anything.

[dean333]

Put the negative side of your meter to ground, the positive to the contact set arm. Open and close the points with the needle of your meter. If the voltage doesn't change, the contact set is not grounded to the distributor plate. I was scratching my head for hours when I had no spark after changing the points on my 57 Studebaker. Took the new points out, scuffed the bottom and also cleaned/scuffed the distributor plate. Reinstalled the points and it fired right up as soon as I turned the key.

[Ross F-1]

Coils do short internally, and sometimes suddenly.

[BUBBAS IGNITION]

Originally Posted by jltrade

I've replaced everything, one part at a time: points, primary wire, condenser, cap, rotor, coil, coil wire. No spark. Have 6.3 volts at coil and confirmed that braided copper wire at points is grounded. I've turned fan by hand to verify distributor shaft turns with crank, and it does. Symptoms lead me to believe that coil is somehow grounded all of the time. Is there anything else that can go wrong systemically within the distributor?

Thats what we talked about above. The lead from the distributor feed to the points is internal under the breaker plate. Cant see it or replace it without further disassembly. Distributor would need to be out of car with drive gear pressed off the shaft to get to the circlip holding the breaker plate down.
Check with ohm meter for circuit not being grounded from distributor primary terminal to ground.....................

Old thread show unit apart , i guess you could replace without tear down but it would be tough in my mind.....
http://fordbarn.com/forum/showthread.php?t=104057

[Cecil/WV]

I've changed the wire under the plate but, I attach a string to one end and pull it through with the wire and them can pull the wire back in with the string. It can be done.

[George/Maine]

I had one that the end of wire connector turned, as the screw was being tighten.
The end was grounding out to case. Just loosened and moved away from case.

[jltrade]

I've replaced the wire from the points to the coil, and the bare copper ground appears secure. Is there yet a third wire lurking under the plate inside the distributor?

[George/Maine]

There is only the 2 wires.
With the ohm meter put the points in middle and see if they make and brake.
Turn engine over or open and close by hand with stick plastic.
Post #6

[rotorwrench]

Coil testers for the can type coils are out there but they are a somewhat complex piece of equipment. They do several tests for open windings & shorted windings and the coil has to be heated to operating temperature to replicate all conditions of normal use. A person can just try another coil too but you have to observe polarity for the type of electrical system that is currently in use, ie 6 or 12 volt and positive or negative ground.

The long and short of it is that they can fail so you will either have to test it or replace it with a known serviceable part if all else is functioning normally.

[jltrade]

OK. thanks to George in Maine, she's running but due to my parts replacement I can't be 100% certain what may have failed, whether it's actually fixed or an intermittent problem persists. I did as George suggested and found that though I described my lack of spark as "always grounded", I was actually NEVER grounded at the points. So I installed a second set of point since the original failure and she started. The apparently defective set of new points was stamped Motorcraft, but also stamped Mexico. Once running I reinstalled all of the original parts that I replaced, except the points, condenser and primary wire, and she's running fine. Still need to plug in overdrive solenoid but didn't fell like climbing under the car this morning.

Thanks to everyone who took the time to respond to my posts.

[George/Maine]

Here is a simple way to check coil and condener.
Put power to coil make sure there are no broken strands end of wire.
Remove points wire at coil
Now put a condenser on coil lug terminal wire end.
Take coil wire out of cap and hold 1/4 to grd.
leave other end in coil.
Get a piece of wire grd one end and touch conderser.
When you make contact and remove should see spark.
Turn key on.

[George/Maine]

Up and running good.