Toasted Second Coil - Extremely Frustrated

I get the impression this is your first old ford. That said, and no offense ment, you know that these cars are positive ground? I would check to see if you have a resistor in the circuit. If you have a multi meter check the wire going to the negative side of the coil, with the key on. You should have 4.5 volts to the coil. If you have six volts you don't have a resitor or it is bad. Hope this helps.
 
I agree the first thing is make certain you only have the 4v to the coil. If do have only 4v going to the coil, go head and pull a plug and check for spark. If you have 6v to coil you need a resistor. You believe you may have heated up the coil charging with ign. on, but it might be fine now that it has cooled down.
 
Last edited:
one thing to check is all your battery cables, starter cable ground at the starter and the ground strap or cable. if you have a loose or dirty connection the motor will spin over but will not start. the coil will not get the right amount of voltage then you will flood the motor and never get it started. I had this trouble, I cleaned and tightened all the connections and my pickup would stat like it had 12 volts. with 6 volts you need big battery cables 2/0 or bigger. the lower the voltage the higher the amperages that is ohms law, you can't brake it. good luck to you, don't give up, you will get this figured out
Brendan
 
Hey guys 6 volts at the coil don't mean there is no resistor in the wire from the ignition switch to the coil. When the points are CLOSED the voltage at the coil wire will be in the 4 volt range. When the points are OPEN the voltage should very close to 6 volts. The coil needs the resisted hot NEG wire to the top of the coil through the ignition switch. The POS ground side to the coil is connected through the points of which one side is to ground. If the points are open only the hot or NEG side of the coil winding is connected through the ignition switch which in effect only go's through primary winding to one side of the points.. There are 2 switches for the coil, the ignition switch and the points. When the ignition is off and the POINTS CLOSED the POS side of the battery through ground is going into the coil but the NEG side of the battery is disconnected by the ignition switch so there is no current flow through the coil. When the POINTS are OPEN and the IGNITION SWITCH in the OFF position or OPEN there is no connection to the coil from either side of the battery. The coil is similar to an AC transformer with the ability to take a low voltage and through it's ratio of windings make the output into a higher or lower voltage. This only works with alternating AC power that go's on and off with every cycle which in our country is mostly 60 cycles or 60 time a second. DC is a steady voltage and a transformer won't work on a steady voltage, this is where the points come into play. They turn the DC on and off as they make and break allowing the coil "transformer" to make electrical changes that produce very high voltages in relationship to the ratio of the primary and secondary windings. There is a more technicial discription but this gives a basic idea of how things work. G.M.
 
Last edited:
G.M. Maybe I'm thinking too simple. On a 6v positive ground system I thought with ignition on there should be only 4v available to the coil neg. terminal reguardless of open or closed points. In comparison with a jumper wire directly from the battery neg to the coil neg. terminal there would be 6v available to coil. Or no resister in line would be like direct from battery and still 6v available to coil. I don't know maybe I'm all messed up. Sorry about that if I am.
 
Last edited:
When charging a 6 volt posative ground you should always remove the battery cables. A friend of mine didn't and ended up blowing the top of the battery clean off. The charger probably wasn't automatic so it didn't shut off and overcharged. What a mess, battery acid all over the place.
Don in SC
 
GM-I disagree-the curent flows from the negative post to the ignition switch and from there thrue the resistor to the coil. The voltage is 6 volts to the ignition switch and then the voltage is 4 volts going to the negative side of the coil (after the resitor). There may be some voltage from the positive side trying to go the other way but it is stoped at the coil-two seperate windings. Even later cars that had the resitor on the coil the power went thrue the restor prior to the coil.
 
G.M. said:
Hey guys 6 volts at the coil don't mean there is no resistor in the wire from the ignition switch to the coil. When the points are CLOSED the voltage at the coil wire will be in the 4 volt range. When the points are OPEN the voltage should very close to 6 volts. The coil needs the resisted hot NEG wire to the top of the coil through the ignition switch. The POS ground side to the coil is connected through the points of which one side is to ground. If the points are open only the hot or NEG side of the coil winding is connected through the ignition switch which in effect only go's through primary winding to one side of the points.. There are 2 switches for the coil, the ignition switch and the points. When the ignition is off and the POINTS CLOSED the POS side of the battery through ground is going into the coil but the NEG side of the battery is disconnected by the ignition switch so there is no current flow through the coil. When the POINTS are OPEN and the IGNITION SWITCH in the OFF position or OPEN there is no connection to the coil from either side of the battery. The coil is similar to an AC transformer with the ability to take a low voltage and through it's ratio of windings make the output into a higher or lower voltage. This only works with alternating AC power that go's on and off with every cycle which in our country is mostly 60 cycles or 60 time a second. DC is a steady voltage and a transformer won't work on a steady voltage, this is where the points come into play. They turn the DC on and off as they make and break allowing the coil "transformer" to make electrical changes that produce very high voltages in relationship to the ratio of the primary and secondary windings. There is a more technicial discription but this gives a basic idea of how things work. G.M.
Click to expand...

You are correct on this ,been there done that. Easy enough to check with a volt meter.
 
6V battery you will have about 4V's across the coil primary and about 2V's across the resistor if the points are closed and the ignition switch is on. You must have current flow to have a voltage drop. Points open, ign sw closed you will have 6V's across the points and 0V's across the resistor and coil primary because you have no current flow. Points closed and ign sw open you will have 0V's across the points, coil primary , resistor and 6V across the ign sw.
 
jrhaelig don't give up theres plenty of advice here ,If you charged with the ignition on the battery wouldn't be charged fully, if at all .The cutoff switch is almost a must for a old car, this should be placed within reach when you are behind the wheel ( don't ask me why ) ,I would say most people here have experienced at least one cooked up coil .Get the new adapters so you can change for a alchepo untill you sort all this .First test the spark of the plug wire with a fully charged battery ,Since the battery is under the floor in the past I have charged my battery by clipping the charger Neg onto the generator cut out then the pos one on a head bolt . If there is no spark We here will tutore you on the next step .If it only sputterd it could be a fuel broblem .Keep us informed
jrhaelig said:
I haven't even gotten my darn truck to make more than a sputter and I have toasted another coil.

I mounted my Bubba's distributor today. He also tested the coil & condenser - they were OK.

Got a sputter, then battery died. Put the charger on. 6 volts. I did notice after the fact that I charged with the ignition switch on.

Went back a few hours later. Cranked it 3 or 4 times and smelled the coil cooking off.

I am tired of hitting failures & obstacles and am beginning to think about cashing out. Progress is fun. Failure is not.
Click to expand...
 
Last edited:
I was wondering if you are using a 6 volt battery charger.
If you have a stock coil not round one and every thing is corrrect,trying to charge with 12 volt charger is no good,and key ON is also no good as you have found out.
Just clean your points and adjust if needed,may need new conderser.
 
I agree that charging with the switch on cooked the coil, despite the fact that the odds are against it.

I hate to be a geek (actually I don't hate it), but with 15 degrees of dwell times 8 cylinders, there are 120 degrees with the points closed and 240 degrees with them open.

The odds of cooking the coil are 120/360 or roughly 33%.
The odds of not cooking the coil are 240/360 or roughly 66%.
 
Mike51Merc said:
I agree that charging with the switch on cooked the coil, despite the fact that the odds are against it.

I hate to be a geek (actually I don't hate it), but with 15 degrees of dwell times 8 cylinders, there are 120 degrees with the points closed and 240 degrees with them open.

The odds of cooking the coil are 120/360 or roughly 33%.
The odds of not cooking the coil are 240/360 or roughly 66%.
Click to expand...

Mike,

Dwell is the period of time ( measured in degrees or percent%) that the contacts are closed allowing the coil to build up. Normal machine setting while running is 36 degrees. They are closed for 36 degrees and open for 9 degrees allowing the coil to fire the plugs. The use of a dual contact set allows some sharing of the amp load when closed by overlapping.
Good math above but backwards ...... :eek:

Odds are if a engine is shut off the points will be closed , NOT open.....

AND you could be a geek , for getting in this discussion this deep.. :D:eek:
 
Last edited:
I think the answers you have recieved are good. AND just to help ya out if you think the contacts are smoked ship it back to me for a no charge service and set up again. You pay only the shipping ....we all make mistakes ...
And dont charge with the key on again...... I have walked into the garage more than once to smell a overcharged battery and burnt parts..........
 
BUBBAS IGNITION said:
Mike,

Dwell is the period of time ( measured in degrees or percent%) that the contacts are closed allowing the coil to build up. Normal machine setting while running is 36 degrees. They are closed for 36 degrees and open for 18 degrees allowing the coil to fire the plugs. The use of a dual contact set allows some sharing of the amp load when closed by overlapping.
Good math above but backwards ...... :eek:

Odds are if a engine is shut off the points will be closed , NOT open.....

AND you could be a geek , for getting in this discussion this deep.. :D:eek:
Click to expand...

Crap! I confused the point gap (.015) with the dwell.
I guess I'm only part geek.
 
1937pickup The resistor don't "resist" until it has a load on it. When the points are open there is no load from the coil the POS end of the coil has to be connected through the points to provide the completed circuit in order to have a load. G.M.
 
I wonder why you smoked another coil.What happen to the first.
I know some people don,t like the starter to be hot all the time but thats the way it was made.You don,t need any extra wires on the key switch.
Pos ground.
The seinode power should be taken from the correct side.Starter motor by it self.
I wonder if wires have been changed and smoking coil some how from seinode.
No body is going to steal it on the starter motor.
 
You must log in or register to reply here.
Back
Top