will not idle or drive

[Frank Gooz]

I need help. all of a  sudden my 1950 coronet will not idle and I can not drive it also.

it will run in the drive way at a high idle but soon as you let off the gas it dies.

I want to check the ballast resistor and I only find a very small section under the transmission were it says that it is 12 ohms not 1.2.

I made many calls trying to find a 12 ohm ballast resistor and are coming up with nothing. Can this be a miss print after all these years and it is 1.2.

I have seen articles about a 7 ohm that was hard to find in regards to a Pertronix conversion, That will be next. 

 I was even told that it does not exist.

Frank 

[Sniper]

2 hours ago, Frank Gooz said:

I only find a very small section under the transmission

 

what does that mean?

 

You had better tell us more about your setup because there is no ballast used in a 6v ignition system, so you must be referring to something else and why the mention of pertronix?

 

12 ohm wire wound ceramic resistors, which is what a ballast is, are available.  But they do not look physically the same.

 

What lead you to look at the ballast?  If it runs at all it's good.  Maybe if it were cutting out after it got heated up but it doens't seem that's the symptoms here.

 

 

[Frank Gooz]

I had found a post were the person needed a 7 ohm resistor for his Tip Toe shift ,with a Pertronix conversion. The resister or ballast resistor information that I found is on page 32 under GYRO-MATIC transmission. in my Dodge shop manual for D29-D42. It is in the same box as the circuit breaker on the brace that also holds the air clearer.

The resistor's wires are black and blue, The black goes to the coil and the blue to the interrupter on the transmission.

Hope this will help someone help me.

Frank

 

[DonaldSmith]

Do you have the Pertronix ignition? The wiring for the Pertronix is vastly different that for the breaker-type distributor.  

 

"Ballast resistors"  are used for the coil on a 12-volt car.  The coil normally runs at 6 volts, more or less.  Some cars bypass the ballast resistor when starting, to send 12 volts to the coil. 

[keithb7]

When you hold open the throttle you are sucking fuel through a main jet in the carb.  Fuel is introduced up in the main carb venturi when the throttle valve is held open. 
 

At idle with the throttle valve closed, you are sucking fuel through the idle circuit jet. At idle, fuel is introduced down low in the carb. Near the base I believe. The idle mixture screw allows for air/fuel mixture adjustment here.  
 

Your latest problem of no idle; could your carb need a good cleaning? Clearing up the idle circuit? Did you by chance play with the A/F mixture screw recently? 
 

If you had a friend work the throttle to keep the engine running, then your helper let off the throttle. Standing by & ready,  what if you quickly, manually sprayed gas in the carb venturi at idle. Would the engine then run? Only while you manually introduced fuel at idle?

Edited June 17, 2020 by keithb7

[soth122003]

I'm with Keith on this one. I think you got some crud in the carb and it fouled up the idle circuit. Clean the carb, because it does not take much especially with ethanol fuel when it breaks down. It leaves a greenish algae like stuff that can clog the idle circuit.

 

Joe Lee

[Merle Coggins]

A vacuum leak will also make for poor idling. Check for loose manifold nuts, loose carb mount nuts, bad vacuum hoses/connections. 

[DonaldSmith]

Revisiting the Gyromatic wiring question, my shop manual includes both the M5 and M6 transmissions.   The M6 wiring eliminated a transmission relay, but added a resistor between the interrupter switch and the coil, among other differences.  The ohm rating of the resistor remains an open question.  If you get any reading, maybe it ain't broke.

 

Frank, you have an S-11 Suburban too?  Welcome to the club.  (Have you considered joining the National DeSoto Club?)

So you have two different transmission wiring systems to play with.  I have some experience with the M5 and the Pertronix ignition.    

[dpollo]

it is possible your timing chain has  jumped a tooth.  check ignition timing with a light and it it has changed to a severely late position there is your diagnosis.

engine will start but has no power and will not drive the vehicle.

 

[Frank Gooz]

Donald

the Desoto club is on my list. Yes I have a L.W.B. that looks like it was once painted like your car. I have some questions about my car that some tell me that can not be.

I had been doing a lot of reading in this forum and also thinking that at last glance that maybe this could be voltage related?

I will swap out the carb just to check off that avenue also. The term ballast resistor that I used could be wrong. that could be from my 60s and 70s Mopar's.

I will want to put in a Pertronix conversion kit after I get back to running good the was it was.

 

I thank everyone's input

Frank

[Sniper]

All right, let's fix what you have right now and leave what you might do later for later.  It's confusing the issue, at least for me, bringing up stuff that isn't part of the issue at hand.

 

Now as far as fuel delivery goes, the only difference between idle and high idle is that at idle the mixture screw supplies the fuel, above that you start getting into the transfer slot, at least on most carbs.  Exactly what make and model carb do you have?

 

 

 

 

[Frank Gooz]

Good morning,

I have read all the reply's and am very grateful for all the input. I did check the resistor and it appears to be just fine at 11 1/2 OHMS . Then I took off the carburetor that was brought up and boy was I surprised at the condition of the insides. The amount of very fine stuff (rust ,sand ?) was  amazing. I slowly cleaned and blew out all the passages with a piece rubber hose. Then removed the hard line from the pump to the carb as to add a fuel filter before the carb.  I have driven the Coronet and all seams to be great once more.

Many thanks to all.

 

Frank

[Plymouthy Adams]

if your resistor is 11.5 ohms..this is your problem as you are throttling back too much on your current to develop a spark.   The resistor should match closely to the primary of the external resistor style coil...normally this is between 1.2 and 1.7 ohms on about any given street application.   Either you have the wrong resistor and coil or you have a defunct meter on measuring the value.  I would place my bet on the meter is bad.  

 

second part, did you for any reason do any tune up, tweak and or adjustment prior to this problem coming up....I ask as recent parts supplied could be at fault and you assume they good from  the box...

 

 

[DonaldSmith]

Which resistor are we talking about?  A resistor for the coil in a 12-volt system, or the resistor in the semi-automatic transmission wiring?

[Frank Gooz]

I was referring to the resistor for the transmission. I had called it a ballast resistor and I think that may have been wrong

All my trouble may have been the dirty carburetor, As I have not changed any thing else

The car seems to be fine now the carburetor was very dirty with very fine sand or rust. I will set the timing readjust the idle mixture and the idle.

Then drive it for a few day s

The only reference to the resistor was in the repair manual when it talked about the circuit breaker. and it said " it is 12 ohms".

 

[DonaldSmith]

All's well that ends well.  Happy Mopar-ing.

[Booger]

Mikes carb shop Carter B&B Youtube video should be required reading for all on this forum