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Ignition coil "external resistor"?

21K views 22 replies 8 participants last post by  Gohot 
#1 ·
87 rC 5.2L...does it have an external? Just bought a new ignition coil but it says
Only use with external 12v resistor. Wondering if mine has one. Anyone have any knowledge
On this?? Thanks a ton
J
 
#4 ·
chrysler300le said:
most likely does mot have a ballast resistor. 87 318's should be lean burn engines. You should still be able to use that coil.
l dont know about the rest of the country but up here in the Nor East "lean burn" trucks are few and far between / my 87 RC 318 is good old chrysler ECM and ballast resisted / the lean burn trucks must of gone south and out west when new / the only truck l,ve seen or owned was an 84 that was a slant six that had lean burn
 
#5 ·
Ditto, most of the trucks I have seen had normal "non-Lean Burn" carb, ECU ignition engines with the common Mopar ballast resistor.  I think I have run into probably a dozen Lean Burn trucks here in town and all of them were in the dealership's shop for issues, lol.
 
#6 ·
#7 ·
Donk said:
I was taking a picture of one of the weld splices here, but in the lower right you can see the ballast resistor (white ceramic). On the firewall near the driverside fender.
Can't say for positive that it's in the same location on an 87, but I imagine it would be in that area.
http://ramchargercentral.com/mopar-trucks/my-85-8'-utiline/msg1601175/#msg1601175
for what it's worth, i have an 87 RC 318 with a lean-burn computer behind the battery and no ballast resistor. i pulled a couple parts off of another 87 318 in the junkyard this morning and it also had no ballast and a lean burn computer.

i guess we down south got all of them. d'oh!

btw - i should say mine had these parts. i have since liberated mine from the leanburn crap....runs much better ;D
 
#8 ·
mcritch said:
for what it's worth, i have an 87 RC 318 with a lean-burn computer behind the battery and no ballast resistor. i pulled a couple parts off of another 87 318 in the junkyard this morning and it also had no ballast and a lean burn computer.

i guess we down south got all of them. d'oh!

btw - i should say mine had these parts. i have since liberated mine from the leanburn crap....runs much better ;D
my '87 came with a 318 and the spark control computer, no resistor. the federal 360's in '87 had the resistor. i'm thinking that a "resistor" is built into the spark computer which should be inside the driver's side fender that year. if you eliminate/bypass the spark computer setup you may have to install a resistor. if you're running the stock setup than you don't need it.
come to think of it that's something i need to look into myself since i bypassed it. although in my case i'm using a GM TBI/ECM controlled ESC.
 
#9 ·
Thanks for all the feedback!
Update**
On my truck the ballast resistor is mounted on the coil itself. Until I looked it up and found
a picture of what it looked like, I wouldn't have known it was there!
 
#10 ·
I don't think the ballast resistor would be mounted on the coil on an '87. This is no guarantee, but here is the engine wiring from the Mopar Parts Manual:



If what you replaced was a little can looking thing with a single wire coming out the end like #6 in the diagram, that was the capacitor, basically a noise filter. The ballast resistor is #13 in the diagram and is usually mounted on the driver side of the firewall, usually under all the bulkhead wiring somewhere. It should look something like this:

 
#11 ·
ZolA049 said:
Thanks for all the feedback!
Update**
On my truck the ballast resistor is mounted on the coil itself. Until I looked it up and found
a picture of what it looked like, I wouldn't have known it was there!
NO NO NO. that little resistor mounted next to the coil is for the heater choke. Don't confuse the two and think that is a ballast resistor for the coil.
 
#12 ·
Elwenil said:
I don't think the ballast resistor would be mounted on the coil on an '87. This is no guarantee, but here is the engine wiring from the Mopar Parts Manual:



If what you replaced was a little can looking thing with a single wire coming out the end like #6 in the diagram, that was the capacitor, basically a noise filter. The ballast resistor is #13 in the diagram and is usually mounted on the driver side of the firewall, usually under all the bulkhead wiring somewhere. It should look something like this:

------

if you have a box like item #2 in the above diagram then you will have a ballast resistor. it looks like this -



if you do not have a box like this then look beside/behind your battery inside the fender well for a box with lots of wires. if you have one, then you have a computer and will not have a ballast resistor.
 
#14 ·
#16 ·
i think it was moved around. previous owner worked at napa autoparts and messed around under the hood. left everything "stock" but messed around none the less.

the motor is on a swamp buggy now thats im about to re wire. my guess is i would wire this thing inline from the ignition switch to the coil? ignition to one point on the resistor then the other point to + on the coil the - coil to distributor?
 
#19 ·
What Chrysler300le is talking about is this little thing:



So if you replaced that, or something that looks similar, that is not the coil ballast resistor. If you replaced something like the one you linked:



And it's about 3" long, then someone has done a butcher job on your wiring as there is no need for the resistor to be mounted there when the factory one is mounted on the firewall.
 
#20 ·
Nope, its the one I linked. Doesnt look anything like
the one Chrysler is talking about. Or atleast like the
one in your first picture.
I would have had to mount it there or atleast pulled it
off the fire wall anyway being that I swapped the motor(87 RC) onto a swamp
buggy (81 trailduster). No fire wall on a swamp buggy! ;D
 
#21 ·
That bit of information would have been more useful in the beginning.  ::)
 
#22 ·
I hear ya but it was mounted on the coil even
When it was in the vehicle itself. Not sure why buy it was. Thanks
For the feedback either way!
 
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