383 Coil resistor

[D Ray's Alien]

I am working on a '70 383 and the coil has a resistor on the negative post.
I am used to GM cars and haven't seen this. Why is it necessary?

How do you check it to see if it is good?

Thanks in advance.

 

[Ross Wooldridge]

I'ts likely for radio ignition noise suppression - remove it and see if your radio gets static...

 

[Davea Lux]

I am working on a '70 383 and the coil has a resistor on the negative post.
I am used to GM cars and haven't seen this. Why is it necessary?

How do you check it to see if it is good?

Thanks in advance.

That is a capacitor and it is used to suppress static from the coil firing as the points open and close. (Chrysler calls it a capacitor, other publications call it a condenser) As noted in the previous post, this helps to limit some of the static noise on your radio. These capacitors usually do not fail but if you hook a tester on the ohms setting to the lead for the unhooked capacitor and the case of the capacitor it should read very minimal voltage draw that slowly increases. If you switch to the DC setting on the multimeter, repeat this same test and you should get a reading that shows the voltage gradually decreasing. The purpose of the capacitor is to absorb and store stray voltage until it fires to ground. If the capacitor has shorted, this can cause a failure to start. The FSM in the accessory section should have the acceptable range data for the condenser, it can be a PIA to find. Note that capacitors store high voltage, ground the lead to the capacitor case prior to starting the above test as a strong electrical shock is possible if you touch the lead and the case for the capacitor at the same times using your fingers.

Dave

Edited post.

 

[Davea Lux]

I am working on a '70 383 and the coil has a resistor on the negative post.
I am used to GM cars and haven't seen this. Why is it necessary?

How do you check it to see if it is good?

Thanks in advance.

Test Procedure for Capacitor/Condenser is attached (For historical reasons, automotive capacitors are called condensers in most of the literature). Click on mail110/111pdf

Dave

 

[Trace 300 Hurst]

The condenser connects to the BATT (+) post, not the DIST (-) post. It's a common mistake that reduces current to the points/coil, causing problems, of course.

The shop manual is silent on this issue....the condenser is not shown in the ignition diagrams, thus the common misconception that this condenser needs to be on the "business side" of the coil. But there's ALREADY a condenser on the business side....it's the one in the distributor that protects the points from arcing.

For that matter, Frank Badalson himself sez so.

 

[Davea Lux]

The condenser connects to the BATT (+) post, not the DIST (-) post. It's a common mistake that reduces current to the points/coil, causing problems, of course.

The shop manual is silent on this issue....the condenser is not shown in the ignition diagrams, thus the common misconception that this condenser needs to be on the "business side" of the coil. But there's ALREADY a condenser on the business side....it's the one in the distributor that protects the points from arcing.

For that matter, Frank Badalson himself sez so.

The coil condenser (Capacitor) is discussed in the "Accessories" section (Pg 1-5) under noise suppression in the '70 FSM. There is even a photo. And you are correct, it is hooked to the primary (hot) side of the coil. There is also two other noise suppression capacitors, One on the back of the instrument cluster wired to the cluster regulator and one on the back of the radio case.

Dave

 

[Trace 300 Hurst]

The coil condenser (Capacitor) is discussed in the "Accessories" section (Pg 1-5) under noise suppression in the '70 FSM. There is even a photo.Dave

That is SO cool you knew about/ found that in the FSM. Good on ya! I just had a look and it came flooding back to me. As soon as I read what you said, I recalled the photo from the deep, dark recess from my 1974 Chrysler dealership $4/hour summer job mind.

I wonder if that condenser is needed with electronic ignition, either OEM in 71 or Mopar aftermarket?

 

[Davea Lux]

That is SO cool you knew about/ found that in the FSM. Good on ya! I just had a look and it came flooding back to me. As soon as I read what you said, I recalled the photo from the deep, dark recess from my 1974 Chrysler dealership $4/hour summer job mind.

I wonder if that condenser is needed with electronic ignition, either OEM in 71 or Mopar aftermarket?

Not sure about that. I installed a bunch of the Chrysler made electronic ignitions and nothing I can remember was said about pulling the condenser.

Dave

 

[Trace 300 Hurst]

nothing I can remember was said about pulling the condenser.

Interesting. I wonder if the answer can be gleaned from a 1973+ FSM (which we could assume was correctly updated by that time).....meaning there is no mention of a coil condenser on Page 1-5, meaning not needed with the Electronical system.

Note: When I was at the dealership, fixing crappola Cordobas and Valiants in 1974/75, I kept wondering "What the hell is a reluctor wheel and what makes it go?"

 

[Davea Lux]

Interesting. I wonder if the answer can be gleaned from a 1973+ FSM (which we could assume was correctly updated by that time).....meaning there is no mention of a coil condenser on Page 1-5, meaning not needed with the Electronical system.

The field for the coil still is going to collapse and produce static. The only thing that changed was an electronic switch versus points. Unless they dealt with the static in the electronics (doubtful) the condenser was probably still needed. Do not have a FSM for '73

Dave

 

[Trace 300 Hurst]

Yep, yer prolly right...still collapsing that field in the coil.

But what about the magic RELUCTOR WHEEL?

 

[Davea Lux]

Interesting. I wonder if the answer can be gleaned from a 1973+ FSM (which we could assume was correctly updated by that time).....meaning there is no mention of a coil condenser on Page 1-5, meaning not needed with the Electronical system.

Note: When I was at the dealership, fixing crappola Cordobas and Valiants in 1974/75, I kept wondering "What the hell is a reluctor wheel and what makes it go?"

Mid '70's to late 70's was a bad time to be a Mopar tech, we had lots of warranty claims, sales on big cars went to hell and so did dealer margins. Lots of claims on ATC ,ATCII, Lean burn ignition, final nail in the coffin was the overdrive transmissions which were all initially a pieces of crap.

Dave

 

[Davea Lux]

Yep, yer prolly right...still collapsing that field in the coil.

But what about the magic RELUCTOR WHEEL?

That is the six or eight point star wheel inside the distributor on the shaft that trips the pickup module and fires the coil, just like magic.

Dave

 

[Trace 300 Hurst]

Magic indeed. We called it the damn star wheel thing.

At the tender age of about 19, I discovered the problem and wrote a "TSB advisory" of some sort back to Mother Mopar for the Viton needle in Slanty carbs. We all know it wasn't supposed to swell, but it DID, the float level dropped a bunch, and when the owner made a turn (only right or only left, I forget which) the car would stumble or stall. I spent a lot of time bending float tangs on those one-barrels.

So glad I finished engineering school and didn't have to fix Malaise Era cars anymore.....