Resistor Coil
 

I am rewiring my 40 Ford and I see there is an ignition resistor on the board with circuit breaker and my question is do I now buy a non resistor coil?
Thanks for the help.

Re: Resistor Coil
 

You only need 1 resistor and yours is where you described. The coil won't make sparks if it gets less than 4 v.

Re: Resistor Coil
 

Mike, the '40 Ford coil has no internal resistor. You need the dash mounted resistor for this coil, which will deliver 4 volts (target) to the coil. If you use an aftermarket coil, odds are it will have an internal resistor, in which case you simply bypass the dash mounted one.

I'm no electrical genius, but as i understand, the ballast resistor is smart, delivering close to 4 volts whether it receives the correct 6 volts or not. It does this by way of heating or cooling, heat in an electrical circuit is resistance in itself.

Now, with that in mind, remember that the starter motor is greedy, grabbing lots of lightning away from the ignition circuit. This is why with some cars, you crank and crank, it won't start until the moment you release the starter. I f you experience this phenomenon, simply create a momentary resistor bypass from ignition switch directly to coil. Never run with this bypass, use it only to start the engine.

More info than you asked for, but good to know for your rewiring project.

Re: Resistor Coil
 

Thanks guys,
I checked with my friend at the auto parts store and he said he can get me a Standard Products Co.non resistor coil for car,he said it should be good,very old company.
Mike

Re: Resistor Coil
 

First of all, are we talking an original Ford-type coil that mounts right on top of the distributor or a modern "can-type" coil? Just make sure the coil itself is not "very old". They tend to deteriorate with age. At least test the primary and secondary windings for the proper resistance. (<10 ohms on the primary and more than 10,000 on the secondary.)

Re: Resistor Coil
 

Mike, I’m sorry to say, nobody in the vintage car hobby has a friend at the auto parts store anymore. Those days are gone, the kid behind the screen cut his chin with his new razor this morning and it bled onto his keyboard so it’s out of action today anyway. If you ask him if the coil mounts on the distributor, he’ll tell you no, I think they mount on the spark plugs, don’t they?

Re: Resistor Coil
 

I still believe the resistor is only used with the Ford coil up to 1948. 1949 to 55 never seen any resistor or Chevys Chrysler prod. etc. with the can coils. 12 volt systems yes
need a resistor. That goes for pos or neg ground. I run a can coil on my 46 no resisor no problem for 16 yrs daily driver...

Re: Resistor Coil
 

Are you changing to 12 volts or staying with 6 volts? Are you using the original style coil or a modern round can style coil ?

Re: Resistor Coil
 

I neglected to say that I put a late model flathead in my car, after dealing with full floating bearings for sixty years I decided to treat myself to a modern engine! Ha Ha.A friend of mine scraped out a 50 Merc years ago and I grabbed the engine.
Thanks for responding.

Re: Resistor Coil
 

Now all you have to do is tell us if your car is still 6 volts or has been converted to 12 volts. Then perhaps we can begin to offer some useful advice.

Re: Resistor Coil
 

Everything is still the stock 6volts,only the engine has changed,sorry.

Re: Resistor Coil
 

Now that we have all the information, we can consider the original question.

I am rewiring my 40 Ford and I see there is an ignition resistor on the board with circuit breaker and my question is do I now buy a non resistor coil?"

My advice, since you are essentially using an 8BA engine, is to bypass the '40 ignition circuitry completely and just run the ignition lead to the 8BA (or compatible) coil. 8BA's did not use a resistor coil. I believe a Bosch "Blue" coil from a Volkswagen is an acceptable substitute.

Re: Resistor Coil
 

Thanks to everyone for all their input, will proceed with the project.

Re: Resistor Coil
 

A Bosch blue coil is a 12 volt coil with an internal resistor.

It has been a while; but if I remember right the post '49 cars used a 6 volt coil an internal resistor.

Guess you have a choice of a non-resistor 6 volt coil retaining the firewall mounted resistor or a internally resisted 6 volt coil and jump the firewall resistor.

Might come down to a choice of which coil is available.

If the one you chose comes from Mexico or China; maybe get two and carry the extra in your trunk.

Quality of this stuff has really gone downhill; just saying.

Re: Resistor Coil
 

Yes, it comes down to coil availability. The post '49 coils did not have a resistor. You want a coil with 1.5 ohms primary resistance. A straight replacement for a '49-'53 Ford would be best. Who knows, you may find a 6 volt Mallory "Best" coil that looks great and works well. In any event I would absolutely eliminate the original '40 resistor because you do not want to mix ignition types. The '40 ignition resistor works on a completely different principle than a modern ballast resistor.

Sorry about the mistake on the "Blue" thing. I do know there is a 6 volt Volkswagen replacement from Bosch that works.

Re: Resistor Coil
 

I have found a Standard Products Co.non resistor coil that will work with my stock Forty Ford ignition resistor that is mounted behind the dash and he said that they are an old company known for quality parts,what do you guys think?

Re: Resistor Coil
 

The Mallory design components that Ford used on the V8 cars were specially made to fit with the distributors Ford used up through 1948. After that, Ford contracted with Holley to use the Load-O Matic design in conjunction with the 8BA and 885 carburetors made by Holley for Ford and Mercury respectively. The Mallory designs all needed a ballast to control the current to the coil for optimal performance and reliability. Straight 6-volts would be hard on them.

The can type coils with the 1.5 Ohm primary never needed current control so they work fine with 6-volt systems. The early 12-volt systems tried to get away with using the same 1.5 Ohm coil in 1956 but they were problematic to they added a ballast resistor to control the current on them or they would get too hot. Ford and other manufacturers did this clear up into the early electronic ignition era.

The modern 3-Ohm primary coil was developed using new materials so it could work on 12-volts with no ballast control. Special epoxy mixtures replaced the oil in these new type coils so they can take the heat with no problems.

Re: Resistor Coil
 

A stock replacement '42-'48 Ford coil would probably work in your situation. They are standalone coils that are available in the aftermarket, designed to be used with the Ford under dash resistor. The problem is they are not configured like a modern "can" coil, but making a special bracket to mount it shouldn't be too difficult. Wiring it up should be straightforward.

Still, knowing the problems some have had with the resistors and their replacements, I would opt with a standard 8BA replacement coil wired directly (eliminating the resistor). Anytime you can reduce the number of components in a system, you are ahead of the game.

Re: Resistor Coil
 

I didn’t want to use the load-o-matic distributor so I bought a new Mallory duel point which is on the engine now.All I’m trying to do is use the wiring harness that I bought from Dennis Carpenter in the stock configuration.
The only reason I made the changes was because it was a 60 horse and just too wimpy!

Re: Resistor Coil
 

Quite simple to do:
Your 40 resistor has two terminals, an in and an out. Just connect your "out" wire (going to the coil) to the in terminal together with the "in" wire from the ignition switch. This bypasses the resistor.

Then follow the good advice from Tubman in the last paragraph of #18.

Re: Resistor Coil
 

One thing to know about the late model Mallory dual point distributors is that some of the early releases came with a Chevrolet advance curve (36° total) whereas a flathead likes 22° to 24°. I see you bought a "new" distributor, but if you have strange problems (like overheating), that is a good place to look. As I remember, there should be a plastic "key" that comes with the unit that is used to select the desired total advance.

Re: Resistor Coil
 

I do remember the key that came with it but all I did was check the point gaps and installed it on the engine while it was on the test stand. It started quickly and ran smoothly while I ran in the new cam,and yes I remember from when we raced flatheads we never went more than 24degrees on the Harmon Collins magneto.