Ignition coil ballast resistor importance?

petex19

True Classic
Years ago and I don't even remember why :hrmph: I disconnected and removed the ballast resistor and the little cannister thingy and just ran the positive wire directly to the ignition coil. I drove it for years like that and last year in an effort to increase the spark I purchased an MSD Blaster 2 coil #8203 which does not require an external resistor and have been using that.

I just got back from my first car show of the season and did lots of driving on the weekend and the car has ran better. It felt like the plugs were fouled so I replaced the plugs and didn't run better over 4000rpms.

I just re-installed my old coil again without the resistor and cannister and took it for a drive and it ran great pulling to redline in all gears :love: but there was occasional backfiring which I thought might have to do with the resistor not being connected? or it could just be from hundreds of miles I drove over the weekend never really going over 3500 rpms. and things just need to be cleaned out with a good hard drive.

Anyone else out there remove theirs using a coil that states that an external resistor is required printed on the front of it?

'PeteX1/9
 
Pete, most coils need the resistor

Although that's not the case with EVERY coil, most do require it.
The resistor limits the CURRENT going through the coil.
Also, if you have a points ignition, it lengthens the life of the points greatly.

It's true that the coil puts out less energy with the resistor, but it's not a lot less.
I'd suggest you use the resistor, regardless.
If you need to find one, go to your automotive supplier and get a 1.25 ohm, 50 watt resistor.

My suggestion only.
 
I still have the resistor and the cannister thingy...

I still have my old resistor and the little cannister thingy which I do not know what it is called exactly.

I know the resistor goes between positive and the coil and I think the cannister thingy connects to the negative on the coil but I am not sure and is the cannister needed?

'PeteX1/9
 
Peter... the cannister thingie is called...

... a CONDENSER the automotive world... and a CAPACITOR in the most of the other electrical and electronics worlds.

Bob may argue with me... but I have always understood this to to be used for ARC suppression in points types distributors and others say it enhances the coils ability to charge and discharge.

The condenser that is usually mounted on the side of the coil is generally there to supress STATIC from being introduced into your AM Radio. In most cases, this can be eliminated and not deter engine performance.

As for the Ballast Resister... Bob says its a current limiting device and I can't argue that... but it does so by dropping (using up) about 3 volts across it so only 9 volts gets to the coil instead of all 12.

Coils that require ballast resisters are actually NINE volt coils, even if they say 12 volts all over them... Those that do not, are indeed TWELVE volt coils.

(Chrysler used to use a ballast resister to RUN an engine but for starting, the ignition switch bypassed it so a full 12 volts were delivered to the coil... for... a hotter spark... and easier starting! Imagine that!)

OLD GUYS like myself in the OLD days of Hot Rodding would eliminate the ballast resisters for a hotter spark... and then wonder why the coils burned out after awhile...

If you wanna run without a ballast resister... do so, but carry a spare coil!

Coninue having fun...
 
Last edited:
Great tips but need clarifying...

Pretty straight forward but what I don't understand is why my '84 X ever had a condensor installed if it is electronic ignition from factory and has never had points? The only change over the years has been from factory F.I to carbies so I don't know if that makes a difference.

So if I understand correctly I connect the ballast resistor to prolong the life of my coil between positive from the ignition module and the positive on the coil and don't worry about connecting the condensor since my X isn't points ignition. Is this correct?

'PeteX1/9
 
My stock 86 has a condenser and resistor

Pretty straight forward but what I don't understand is why my '84 X ever had a condensor installed if it is electronic ignition from factory and has never had points?

'PeteX1/9

Hi Pete,

I don't know how it all works, but my completely stock 86 has both parts present.

You can see the condenser in the upper right on the engine cover hinge near the coil.
IM001682.jpg


Ignore the yellow circle. :) This is an old pic for another purpose, but you can see part of the resistor in the lower right.
86_coil_1.jpg
 
Correct!

Hmmmm... as for the static suppression CONDENSER...

Why not prove the NEED for it to yourself and to the rest of us...

Tune your AM radio so that ignition noise can be heard... usually to a weak or NO station... then connect and disconnect the condenser and see if you can notice, see, or hear... any difference. Go for a drive also.

(It sure is interesting that most FI cars seem to have it installed and then again, on the BERTONE drawing it is not shown!!!)

We will be here waiting...
 
I re-connected everything....

I re-connected my original coil and connected the resistor and the cannister to the positive lead of the coil and the engine fired right up and sounds great. I haven't driven it yet so I don't know if I will notice a difference from not having the resistor connected but if it will lengthen the life of the coil then it's worth it. I painted everything so thier purdy and fit in.:)

'PeteX1/9
 
Good... but I expected some form of plating!

HA!

Do the experiement though... yur young... you have plenty of life ahead of you... then tell us what ya find!
 
Back
Top