good spark at plugs but no Henry jiggle

[fried okra]

My '31 Tudor with 12v negative ground is not starting. Cranks fine though.

I've got a good strong spark on a grounded spark plug when cranking the engine, but no deflection of the ammeter when turning the ignition switch on or when cranking the engine.

Does that tell something maybe?

[The Master Cylinder]

Originally Posted by fried okra

My '31 Tudor with 12v negative ground is not starting. Cranks fine though.

I've got a good strong spark on a grounded spark plug when cranking the engine, but no deflection of the ammeter when turning the ignition switch on or when cranking the engine.

Does that tell something maybe?

Depends on how your car is wired. Is your ignition connected before or after the ammeter?

[fried okra]

I am not sure of that.

I lost spark, swapped distributor out and now with a different distributor have spark but no Henry Jiggle.

Seems I used to have the Henry jiggle in past times.

[Roxo]

are you sure your getting fuel to the carb.

[Rob Doe]

Spark at one plug isn't strong enough evidence. I would pull the coil wire out of the distributor cap, use an insulated pony clamp to position the wire 1/4" from a clean head nut, make sure the coil wire is full up into the coil secondary terminal.

Parking brake set, tranny in neutral, ig switch on, stand at the left side of the car and use your hand to engage the starter switch. Turn the engine over and you should get a clean, snappy blue spark on every compression. If you only get a weak, yellowish white spark, or only an occasional spark every few cylinders, suspect the primary ignition, i.e. points, condenser, unintended current draw, coil etc.

If you get a good, snappy blue spark on each compression, I'd check for fuel as stated above.

[nkaminar]

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Rotate engine so that the points are closed. Turn on ignition switch and see if ammeter dips. If it does you have things wired so that the ammeter will read ignition current. If not, ground moving point and try again. If you now have a dip then the points need cleaning. If not then you have a problem in the wiring or the wiring is not hooked up so that the ammeter will read ignition current.

To read the ignition current, the current to the points must be down stream from the ammeter. Consult the Service Bulletins for the wiring change, page 390.

[Anteek29]

What is a Henry Jiggle - an old time dance step?

[nkaminar]

Alan, After the ignition wiring was changed sometime in the production of the Model A, the ammeter would show the current that the ignition was using when the points were closed. When the points were open no current was flowing through the ammeter. When the car is cranking with the starter motor the ammeter would wiggle back and forth when the points were closing and opening. This is usually a good way to check that the ignition system is working. But not always. Take the rotor out and try to start the car. You will get the Henry Jiggle but the engine will not run.

[Big hammer]

You can get the jiggle but no spark because the points dirty ( high resistance ) it will allow voltage to ground but but with no amperage to power the coil and creat a spark or very weak spark………… clean and gap the points ! Quit chasing you tails Tom Wesenberg carried a piece of abrasive paper in his billfold to clean points RIP. I use cereal box, parts box cardboard with the ruff side and pull it through the points until there is no more black showing on the cardboard. I then go for a drive and enjoy !

[fried okra]

In my case, I have spark when cranking the engine, but no Henry jiggle.

Is that logical?

[Big hammer]

Let’s get away from the jiggle for now, an A will run with or without the jiggle. You say you have spark ! at one cylinder or all 4 ? It would be nice to know if all 4 are sparking.

Check to see if your timing is correct, with all of the spark plugs out, connect the #1 on the distributor to a spark plug laying on a head nut ( you can use a jumper wire ) , with the hand timing lever up turn on the key switch and crank the engine over by hand watch for spark at the grounded plug.

If you have a good spark ? remove the timing pin and invert it back in the hole, with your thumb on it pushing in hand crank the engine while looking for spark at the grounded plug, you should feel the timing pin move in slightly and see the spark at the same time. This will verify that the timing is correct.

Now that you know the timing is correct and you have spark at all 4 cylinders, put everything back in its place . With a fully charged battery let’s see if it will start, turn the GAV open 3/4 to 1 turn open , gas valve open , hand timing lever up , throttle lever down about halfway, key switch on , pull out the choke and hold , hit the starter cranking 2-3 times and release the choke, it should fire up now.

If it doesn’t fire up repeat one more time pulling the choke out for 2-3 , it should be running. If it doesn’t start up, get out and see if you have fuel dripping out of the carburetor. In the Ford operation/ instruction manual after turning your engine over 7 times you should have fuel dripping out of the carburetor. If no fuel dripping you have issues with the fuel system.

[Chuck Sea/Tac]

Are you sure it’s an ignition problem? After trying to start the engine, are the plugs wet? I like to spray a little ether in, to see if it will cough, to prove whether the problem is fuel or spark. How old is your gas? Old gas sometimes will not ignite!

[nkaminar]

Fried, Consult the Service Bulletins for the wiring change, page 390

[fried okra]

Thanks, nkaminar......Service Bulletins are on order, hope to get them soon!