No Spark and Stumped!

[Lena's Dad]

I've tried everything I can think of, but no spark to the distributor / plugs. New fully charged battery, new condenser, verified point and rotor gaps, filed points, checked continuity on all wiring, checked wiring diagram and all connections correct EXCEPT at the ammeter, where yellow is on left post and black tracer on right. The other way sent the needle positive when pop out switch turned on. Generator bench tested and producing more than 7 volts. Cut out switch new. New coil warms up if I leave the pop out switch on for very long. Starter rolls the engine over well....
I may have a short, but can't find one.
Lena's Dad

[gweilbaker]

Is the ignition cable threaded too far into the distributor? It will short out the points if so.

[Bob C]

Is the rotor turning as you crank the engine over??

Bob

[Lena's Dad]

Checked on that and don't think so. Pop out switch end is 3 good thread turns out from distributor body. Continuity checked between switch end and condenser screw - nothing until ignition switch turned on.

[Lena's Dad]

Rotor turns fine..

[Tom Wesenberg]

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Sometimes the terminal on a repro switch can short to the gas tank. Stop the engine with the points OPEN, or place a piece of plastic between the contacts to keep them open. Then turn the key on and start tracing back to the coil to see where you last show voltage.

[solidirish]

I just had similar problem and hi side of coil was bad and also had a bad hi voltage wire to the distributor.
Prior to that I had one of the terminal box load scews back into the fire wall creating a short...really poped the fuse even breaking the fuse glass.
Ray in Ilinois.

[Will N]

What kind of point are you running, modern or original? I've seen modern points where the plastic insulator on the post had melted due to a short in the condenser. After the condenser was changed, we still had a short as both the point arm and the stationery point were both receiving voltage.

Same thing could happen on the orig setup if the wire from the lower plate were somehow grounding out on the upper plate.

[Lena's Dad]

Tom,
Voltage reading as follows: Condenser screw to ground .11 volts. Distributor cap wire to ground .28V. Right side terminal to ground .28V. Left side terminal to ground 5.7V.
Black coil wire is on left side per updated diagram and "Jiggle" article, but that's not the way the Ford Manual for '29's is printed. I'd say the coil might be suspect, but continuity reading from left to right post showed only .001 which seems to be in spec.

[Tom Wesenberg]

I prefer to use an analog meter when checking Model A voltage, but if you have the points open and one coil primary has voltage, while the other has no voltage, then you have a short between the coil and points. I'd pull the instrument panel forward and check for voltage on both sides of the switch. Or you could first unscrew the cable from the distributor and check the brass spring loaded contact for voltage. If it has 6 volts, then the short is inside the distributor. The most likely short inside a distributor is the wire or terminal on the wire between the top and lower plates.

BTW, when checking the brass contact for voltage be sure to keep the probe on it while you push it in about 1/4". Sometimes a broken wire strand can short to ground when the contact is pushed in, or if the insulation is old and cracked off the wire.

[Lena's Dad]

Ray,
Pulled the wires from the terminal posts and checked continuity on each to ground. Nothing. Good suggestion though.

[Lena's Dad]

Ray, I'm running original style points.

[gweilbaker]

Do you get 5.7v if you unhook the low reading voltage wire(to the points) on the coil?

[solidirish]

Just to be sure, replace the hi voltage wire from the coil to the distributor. Also on the battery, you should get over 6 volts (more like 6.26v) on a fully charged battery. Under 6 volts suggests a bad battery to me.
Ray in Illinois

[Lena's Dad]

Tom, I pulled the dash and checked the red wire to ground. Using an analog volt meter I got a reading of 6 to 7 volts, but that was with the switch OFF. When I popped it out, I got no reading. Can't check the other wire as it terminates within the switch itself, unless I pull the distributor (it's located inside the spring of course). The last time I checked the continuity at the brass contact, I had none while the switch was closed but got continuity with the switch popped. Bad switch?

[Lena's Dad]

Ray, 6.22V at the battery.

[Purdy Swoft]

The condenser may not be grounding to the distributor housing check the screw on the right side where the condenser connects to the housing for tightness. too much paint on the housing could effect ground. The tab on the lower plate may be grounding to the housing on the left side of the distributor where the condenser connects to the lower plate. There should be a fiber washer glued to the outside of the tab on the lower plate where the condenser connects to the lower plate. The glued fiber washer prevents the lower plate connection to the condenser from shorting to the housing of the distributor.

[solidirish]

Just thinking of your voltage readings....you should be sure the ground points on your distributor should have a good contact to the engine..the grouve for the upper distributor plate should be bare metal, not painted, and the base of your distributor and engine contact area should be clean metal. Also your battery cables should be 00 copper.
Ray in Illinois

[Lena's Dad]

Unhooked red wire at the coil per your suggestion and got a 6.27 reading at the terminal to ground. Looks like the problem is the re-pop switch, does it to you?

[Lena's Dad]

That all appears to be in good order. Also wire connecting lower to upper plate in distributor is new and tight.