Constant spark at all four spark plugs

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Model T Ford Forum: Forum 2005: Constant spark at all four spark plugs
Top of pagePrevious messageNext messageBottom of page Link to this message  By Sam Renck on Tuesday, March 18, 2008 - 07:54 pm:

I am very new with model tís and have very little knowledge of their engines or ignitions. The 1914 touring I am trying to get started is getting a constant spark at all four of the spark plugs when I connect a 12v battery to the battery post of the coil box and have the key switched to bat. I was wondering if this is normal or if something is not wired properly. If I disconnect the battery and crank the motor with the plugs out I do not get any buzz from the coils or any sparks from the plugs. Please help I cannot wait to hear this thing run..


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charles Martin on Tuesday, March 18, 2008 - 08:19 pm:

Get a copy of the wiring diagram and trace out the wires. Sounds like someone did not wire the timer correctly. I don't have a copy on this machine, I am sure another member will post it for you. Whats the history of your T? Did you ever see it run? Recently restored?
Good luck!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick - (2) '26's - Bartow, FL on Tuesday, March 18, 2008 - 08:43 pm:

Hi Sam. Welcome. Model T's were originally designed with a 6 volt system. Unless your Model t was converted to a 12 volt system, you should be using a 6 Volt battery.

Do you have any books to help you along? If not, please explore the Forum for information using the keyword search, before jumping right in, or you could get badly hurt. For some basics, click onto some past Forum threads:

www.mtfca.com/discus/messages/29/15776.html
www.mtfca.com/discus/messages/29/25706.html
www.mtfca.com/discus/messages/29/49201.html
www.mtfca.com/discus/messages/29/42152.html

Good luck.

Jim


Top of pagePrevious messageNext messageBottom of page Link to this message  By Thomas J. Miller "Tom" on Tuesday, March 18, 2008 - 09:16 pm:

Sam, to pin down the problem, first disconnect one of the four wires on the coil box that are above the spark plug wires. If that spark plug stops buzzing, it is a good bet that the wiring harness running from the box to the commutator has gotten eaten or the insulation has broken down allowing the wires to all ground out. Also remove the commutator from the front of the engine and make sure all is well there. With good wiring and the commutator in your hand, there should be no coils buzzing since you have broken the ground circuit on the primary side of the coils. If the commutator has the original roller, make sure it's not excessively worn and the commutator is lightly oiled and not rusted. Your coil box is designed to run at a maximum of around 27 volts on mag. Whether you're pushing 6 or 12 volts through it will not make a difference on this problem.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Sam Renck on Tuesday, March 18, 2008 - 09:46 pm:

Charles, the guy I got the car from had most of the car rebuilt about 20 years ago but never started the engine. I am not sure where he got the car but he has kept it in great shape. I am working on it with my dad and we plan to get it running and then finsh the restoration.

Jim, thank you for the links, what I have read so far is helpful. I have bought the "ford instruction book" and the "Model T Service & Repair Manual".

Tom, Thanks for the ideas I will try them next. I have checked the commutator and all is well there the best I can tell.

One thing I see on all drawings of wiring for a Model T is a magneto terminal but nothing I see on this car looks anything like the ones in the diagrams.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Mullin on Tuesday, March 18, 2008 - 11:18 pm:

Sam,

This wiring diagram is for a 1915 Ford with electric headlights, but is otherwise similar to your 1914. Just erase the headlight wires and the little round switch near the coil box. Headlights were fed by the magneto coil box connection.

1915 wiring

One thing to remember while doing your trouble shooting is that each of the four coils always has battery voltage (or magneto voltage) applied through the switch and the bottom contact on the coil box when switched to BAT (or MAG). The indivdual coils are selected one at a time by the timer (commutator) grounding one coil's wire at a time. One way for all four coils to fire at the same time is for there to be a short in the cable grounding all four wires at the same time. Also, each coil will buzz as long as its contact is grounded. That is why you will sometimes have the car start running as soon as you turn the switch to BAT.

This second picture shows the magneto contact on my 1916 Touring. Yours should be similar. They did change some over the years.

1916

Be sure to let us know what the problem was when you get it tracked down and fixed.

Tom,
Piquette Ts / Casual Ts
Detroit


Top of pagePrevious messageNext messageBottom of page Link to this message  By Thomas J. Miller "Tom" on Tuesday, March 18, 2008 - 11:21 pm:

Sam,

Which end of the magneto terminal are you looking for? On a 14 or any T that doesn't have a dashboard with a switch and ammeter, the magneto terminal is on the coil box on the lower side of the box, drivers side. The other terminal on the passenger side is where you've hooked your battery.

The other end of the magneto wire goes to the magneto post that is just above the transmission band access door immediately behind the cylinder block.

Do not connect any kind of power to the magneto terminal as you will demagnitize your magneto.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Noel on Tuesday, March 18, 2008 - 11:24 pm:

Tom,
I received image boxes but no images???
Noel


Top of pagePrevious messageNext messageBottom of page Link to this message  By Noel on Tuesday, March 18, 2008 - 11:25 pm:

Tom, Scratch the above message. I went to check my entry and your pictures were there this time??
Noel


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ray Elkins on Wednesday, March 19, 2008 - 04:53 am:

One thing you mentioned that puzzles me;

"when I connect a 12v battery to the battery post of the coil box and have the key switched to bat"

The battery doesn't connect directly to anything on the coli box. It should be connected to the switch terminal marked BAT.
Ray


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Cook on Wednesday, March 19, 2008 - 07:14 am:

Ray,

On a 1914, the wiring is quite simple. 10 post on the back of the coil box. 4 for the commutator, 4 for the spark plugs, 1 for the magneto, and 1 for the battery (any voltage 6, 8, 9, 12, 18, 24). The coils don't care about the voltage. Voltage only becomes an issue on cars with starter motors. The battery/magneto switch is on the face of the coil box and is all part of the box wiring.

As for the problem at hand (all the coils firing together) check the condition of the wood in the coil box. Wet wood or carbon arced wood can cause more than one plug to fire at a time. Number 3 can also fire all of the time if the bottom screw of the commutator is touching the engine bolt below it. This bolt is normally turned upside down so that the nut is on the bottom.

Tour America,
JC :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Sam Renck on Wednesday, March 19, 2008 - 06:14 pm:

I got the plugs to work properly. One of the posts on the commutator had grounded out to the engine block. I fixed that and the spark plugs are now firing in order. Thanks for everyone's help.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Leipold@mm.com on Wednesday, March 19, 2008 - 07:12 pm:

The Model T, as original, is not a 6 volt system, but rather more of a 9 to 12 volt. The mag turns out 12 volts and higher. Head light bulbs for use on magnetos ( the blue ridged ones) were 9 volts. Original coils were set up for 12 volts and are far superior to new ones sold today. I use a 12 volt battery to back up my mag in my 1910. I also use old stock KW coils (from about 1955, when they were close or the same as orignal ones.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Mullin on Wednesday, March 19, 2008 - 08:57 pm:

Sam,

Glad to hear the fix was so easy. Isn't that Model T engine sound great!

Tom


Top of pagePrevious messageNext messageBottom of page Link to this message  By Sam Renck on Wednesday, March 19, 2008 - 09:14 pm:

Tom,

Well I haven't heard it yet. I have a good spark at all the plugs but I am not able to get the car to start. I think it is the carb. We took it apart and think that the lead "float" just in front of the spray needle was stuck from sitting so long. After freeing up the "float" it seemed to fire a little easier but we never could get it to take off. I hope to have better luck tomorrow when my arm is not so tired.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ray Elkins on Thursday, March 20, 2008 - 05:00 am:

Well, Jim...if I had read the post a little better I would have seen we were talking about a '14. My mistake :-)
thanks
Ray


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Cook on Thursday, March 20, 2008 - 09:24 am:

Ray,

I knew where you were coming from with your statement. I just didn't want Sam to become confused. Keep up the good work.

Sam,

You need to find someone who knows how to drive a Model T. Pull that T behind another car with a good long strap or rope. Get your hand signals down ahead of time and start pulling. The operator of the T will start out in low and be ready to apply the brakes at any time. (that's why you need an experienced driver) Once you get the carburetor set correctly, the car will start a lot better. People will tell you to open the adjustment a certain number of turns; but, that procedure only works on a rebuilt "know" piece of equipment. An old carburetor adjustment could be anywhere.

Tour America,
JC :-)


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