Modern 6 volt coil in an emergency situation

[desoto1939]

I have a question for the GURUS of the club.

 

Here is the question:

On my 39 Desoto I have the type of Autolite coil that mounts through the firewall. The ignition switch is the armored cable wire that mounts on to the back of the coil.

Then there isa single wire that screws onto the top of the coil and runs to the tab on the breaker plate.  I also have the foot style starter assembly setup.

car is still 6v positive grounded.

 

OK

So lets say that one day I am driving and the cars stops running because the 6v coil goes bad.

 

Get to a local NAPA or Autozone store they will not have the original style 6v coil with the mounting of the wire at the base and the other wire on the top.

can only get the more modern style with the two threaded studs on the outside of the coil.

Also assuming that the studs are marked Positive + and the other Negative -.

SO now I want to connect the wire from the from the armored cable from the ignition switch which stud do I attach a jump wire to and also jerry rid a connection on the armored end of the ign wire.

I am assuming that since the are is POSITIVE GROUND that I would attach the temporary wire to the POSITIVE Stud on the new Modern Coil  and the old wire that I had on the old original coil would then attach to the negative stud and still attach to the breaker plate tab.

 

I am not an electrical master but someday this might happened and just want to make sure I have a backup plan.

 

Also I have been told that coils are either Postive and or Negative style coils.  Is this true or am I getting a run around.

 

Hopefully this will be an education opportunity for everyone that has my style of car with the cowl mount coil.

 

Rich Hartung

Desoto1939@aol.com

[Plymouthy Adams]

get a coil that is 12 volt external resistor…...these are ALL basic 6 volt coil....as for the negative and positive...it could care less at the polarity as long as it is connected...BUT...as the polarity is wear related...manner of material transfer on the point contacts...do hook it up polarity as that of the old coil you are replacing it and not points along with it........if + ground then + side goes to the distributor...negative to the supply......

Edited January 26, 2020 by Plymouthy Adams

[desoto1939]

Plymouthy:  You are always so quick to answer someones question, Rich Hartung. Hope all is going well with you down South.

 

So if a modern coil  and my car is positive grounded then the + or positive terminal on the new modern coil is the wire that runs down to the breaker plate just like it currently is now since there is only one terminal available onmy factory coil.

 

Then connect the wire that is coming from the starter ign switch directly to the Negative - stud on the new modern coil.  This would then get me home and then I could replace with my spare or other backup coil that is inmy spare parts.  I carry a NOS original spare with me in the truck but never know  if that could be bad also.

 

Just trying to be proactive as these cars get older and so do I.  I am not as old as the car

 

Rich Hartung

desoto1939@aol.com

[Plymouthy Adams]

would be an easy task for you to put a modern mount ring on it.....make provisions for a quick wing nut mounting under the hood, prewire with clip in leads for quick hot wire and you be home to address the permanent fix with little to no down time along the road....it is always wise to be proactive and have a contingency plan in place.....as for the south, been a very mild winter thus far....I do not complain....we have had our share of the wet..but sure beats any thought of snow...my hat is off to those that stick it out up north.....great place to hunt and fish...lol

[Loren]

all good advice.

I was taught about a hundred years ago that it was important to get the polarity right.

If you got it backwards the coil would put out about 40% less spark, something in the intervening 99 years I haven't been able to confirm.

It's true that point wear (erosion or pitting if you will) does increase with the wrong polarity and it's said you can tell by which way the points pit (or transfer material) if the polarity is wrong.

The rule is the points are the ground for the circuit. If the car is positive ground then the positive side of the coil is connected to the points, if negative ground then the negative side of the coil goes to the points. Easy peasy.

 

A little history: Charles "Boss" Kettering was the genius who invented what was known as the "Battery Coil Ignition" what we call the point type ignition. His company the Dayton Electric Company was bought out by Billy Durant's General Motors and merged with another company that made automotive electrical parts, Remy to become Delco-Remy. I am told by the really old-timers that Remy had a reputation for making rather inferior equipment, while Delco made excellent equipment. So Durant merged the strong with the weak. Billy Durant had a good eye for talent and hired Walter P. Chrysler to straighten out and save Buick. Durant however was such a flake he frustrated WPC till he quit. Kettering went on to invent the self-starter, the Tetra-Ethel-Lead fuel additive and improve the Winton 2 cycle diesel engine (Detroit Diesel, Cleveland Diesel and Electro-Motive-Diesel).

 

[busycoupe]

I know that people say that coils are blind to polarity, but I am not so sure. about 10 yrs ago I had a 1971 Triumph motorcycle that had positive earth.  It was the very devil to start until I noticed that they coils were wired for negative ground.  I reversed the connections and voila, the bike started on the first kick after priming.  It may have been just because I loosened, cleaned and reconnected the wires, but I am not sure.

[Sniper]

I helped a neighbor get his Bug running that had the same reversed polarity at the coil issue, it would not start till I corrected it.

[greg g]

Real emergency, make and carry a piece of 12 gauge wire about 5 feet long with alligator clips on both ends. Need to power a temporary coil to get home? Clip one end to the neg term on the battery, one end to the pos terminal on the coil.  Coil is hot, start car, drive home open hood disconnect jumper wire, for engine off. When I needed to do that, I duct tapped the coil to the e brake cable to keep it secure.

[Plymouthy Adams]

1 hour ago, Loren said:

all good advice.

I was taught about a hundred years ago that it was important to get the polarity right.

If you got it backwards the coil would put out about 40% less spark, something in the intervening 99 years I haven't been able to confirm.

It's true that point wear (erosion or pitting if you will) does increase with the wrong polarity and it's said you can tell by which way the points pit (or transfer material) if the polarity is wrong.

The rule is the points are the ground for the circuit. If the car is positive ground then the positive side of the coil is connected to the points, if negative ground then the negative side of the coil goes to the points. Easy peasy.

 

A little history: Charles "Boss" Kettering was the genius who invented what was known as the "Battery Coil Ignition" what we call the point type ignition. His company the Dayton Electric Company was bought out by Billy Durant's General Motors and merged with another company that made automotive electrical parts, Remy to become Delco-Remy. I am told by the really old-timers that Remy had a reputation for making rather inferior equipment, while Delco made excellent equipment. So Durant merged the strong with the weak. Billy Durant had a good eye for talent and hired Walter P. Chrysler to straighten out and save Buick. Durant however was such a flake he frustrated WPC till he quit. Kettering went on to invent the self-starter, the Tetra-Ethel-Lead fuel additive and improve the Winton 2 cycle diesel engine (Detroit Diesel, Cleveland Diesel and Electro-Motive-Diesel).

 

 

pitting depends on the polarity as to which side of the contact transfers the metal......as for the 40% I do not think that is anything near true....and only if racing would you may come close to any point shy of full performance as a daily driver performs....and there is not a person on this forum winding their car out to peak RPM in each gear with sustained runs of 90+ MPH and if so,...their ignition is well beyond stock for this application.

[Sniper]

a simple engine scope measuring coil output with both proper and reversed polarity would answer the question.

 

I recalled that the coil in my 51 was wired backwards and it ran just fine.  So I think, no hard data to back it up, that there is some loss and an inherently weak ignition system will notice that loss more so than a good one does. 

 

[keithb7]

Seen here is a new modern 6V coil installed in my 1938. Have you seen what those original type  coils are selling for? No thanks. I think Paid about $12 for this Blue Streak 6V coil. 

 

The Coil has all wire mounts at the one end. The yellow negative wire seen, travels back through the firewall to my key switch. The Positive wire (white seen here) goes to the points. When points close, positive then goes to ground. Positive ground system in use here. The magnetic field then collapses and the high voltage heads out the sparkplug wire. It all works like a charm. 
 

 

Edited January 27, 2020 by keithb7

[desoto1939]

keithb7:  Thanks for the picture of your modern 6v coil that you have installed in the firewall.  I have the style original coil but as you state these old 6v coils are costly and you are not sure if they even will work vs a new 6v coil that sells for around $20 and you know it has full power.

 

Rich Hartung

desoto1939@aol.com

[greg g]

Rich, do you know where and when De Soto Club National is for 2020?

[_shel_ny]

I think if I was concerned about a possible coil failure, and might be faced with going over to the auto parts store to get one to rig up I , for the money, would already have one in the travel parts box all wired up with written instructions for connecting it.

 

Why?

 

When the car quits because of the coil failure you are faced with getting to a parts store. Not easy with a vehicle that is not running.

 

There has to be a auto parts store open when you need the part.

 

Why not? 

 

Line in the sand as to how many parts you carry.

 

If always close to home the car can be left where it quit until fixed. You walk, or take an uber home, or camp out like G.W.

 

[TodFitch]

3 hours ago, _shel_ny said:

I think if I was concerned about a possible coil failure, and might be faced with going over to the auto parts store to get one to rig up I , for the money, would already have one in the travel parts box all wired up with written instructions for connecting it.

 

Why?

 

When the car quits because of the coil failure you are faced with getting to a parts store. Not easy with a vehicle that is not running.

 

There has to be a auto parts store open when you need the part.

 

Why not? 

 

Line in the sand as to how many parts you carry.

 

If always close to home the car can be left where it quit until fixed. You walk, or take an uber home, or camp out like G.W.

 

 

My minimal tool kit, always on my person, is a AAA+ membership card and a cellphone. I’ve actually used these more with my modern car than with my old Plymouth.

 

For the Plymouth, if I can’t fix the issue with the limited spare parts and tools that I carry in the car (spare light bulbs, spare tire, jack, tire iron, and a took roll with adjustable wrench, screw driver and pliers), then it is easy to get the car home as long as I’m within the 100 mile range of towing the AAA+ gives me. If not within 100 miles of home, I am likely to be within 100 miles of a town with a decent auto supply and a motel.

[Merle Coggins]

8 hours ago, greg g said:

Rich, do you know where and when De Soto Club National is for 2020?

 

I believe I heard it's in Brookfield, WI this summer. (western suburb of Milwaukee) I remember that as I was thinking of driving down there for the day and "crashing" the party with my Dodge Truck. I don't recall the dates though.

[Loren]

I really don't believe one needs to carry a spare coil.

The failure rate of ignition coils is so small as to be unimportant.

All the other ignition parts have significant failure rates, caps, rotors, wires, spark plugs all crap out more.

Condensers got changed with points mostly out of insurance. I've changed more ignition switches than coils.

The biggest reason I changed coils was corrosion. The one notable failure I can remember was one that exploded. It was mounted pointing down and it had leaked for years at the seam between the can and the insulator. One day the owner left the ignition on, it got hot and blew the end off sending hot tar everywhere.

I think if you see some leakage I'd worry, if not then don't.

A good exercise is to run the engine in a dark garage and watch for electrical "leakage" around the ignition parts. Caps, wires and even coils sometimes light up with leaks.

What I would carry if you're concerned is a small can of WD40. It helped me finish a race after hitting a puddle once.