Re: {Chrysler 300} Trouble in F land.

On Wednesday, August 16, 2023 at 10:45:18 AM UTC-5 jkg wrote:

Hi Rich , correct data , however the DC resistance of the ignition coil ohms is in series with the ballast , lowering the current ; .6 ohm in 12 v would be 20 A , and your 10 A number probably assumes about .6 for the coil , about right .
However at idle the dwell time closed ( time per spark — not degrees) is very long , the coil saturates and the current rises , per spark , the ballast gets hot and current drops a lot to protect points and coil . Especially if ignition is on motor not running points closed (!) . That situation pops a marginal ballast.
This is why you should never put a “ high performance “ coil on the car without knowing the resistance of the new coil primary . Low aftermarket ohms , in an attempt to get hotter spark , will burn out ballast and burn points . And not give you a hotter spark either . It is well designed , just as it is .

What helps with a hotter spark is more angular dwell at high rpm , why mopar dual points . That second set closes early , single point you have to wait to close as it goes over bump of cam , translates to maybe 15-20 % more time to “fill up “ the coil magnetic field , a fixed time set by physical coil L / R ratio —- on the order of 2-3 milliseconds .
So that dual point gives you 15-20 % more rpm before the same spark fade ( % varies , just an example ) .
Direct AB comparison of 300B distributor on a 354 on dyno vs best MSD made showed zero difference in HP ( 600$?— for what ? more troubles?) , at 5800 rpm . I saw this personally only because MSD failed on the dyno tun . … as they are prone to do in cars too) ; guy who owns dyno said “I see that all the time” .
A curse for Chevy guys .., They DO see better with MSD , right up there with stock mopar .
We adjust points and keep going just like new

They were ok for Petty at Nascar , ok for me too . Very fussy to get right you need a dwell meter .
Agree too , ballast is either ok or dead , rarely would come and go . That is typical of capacitor , which then gives a very weak spark .
jg
Sent from my iPhone

On Aug 15, 2023, at 8:56 PM, 'John W Sager' via Chrysler 300 Club International <chrysler-300-cl...@xxxxxxxxxxxxxxxx> wrote:

The last one I had fail was years ago, so I'm going by memory.

The failure was with an open back ballast resistor and as I remember, the resistance wire was broken along with the ceramic rod that the wire was wound around. If I had to bet, I'd say the rod broke first. Probably running a little hot and then got wet.

I have seen a few fail on other cars were there was actual physical damage to the ceramic block itself and that let the terminals flop around until the connected resistance wire failed, probably from vibration. How they got damaged in the first place was anybody's guess. Although I think I might have broken one on my own car during a late night engine swap.

John

On Tuesday, August 15, 2023 at 08:06:11 PM EDT, Rich Barber <c3...@xxxxxxx> wrote:

Many/most electrical problems are at connections. The ballast resistor has good solid connections to spades on each end plus two connections inside the ceramic housing joining the resistor wire to the spades. The ballast resistor on our K is open at the back to allow heat transfer and some protection from underhood environment. The resistance wire itself may deteriorate after years of service at high temperature and vibration. Has anyone examined a failed resistor to see what failed? I would think intermittent connection of resistance wire to be unlikely.

I just measured the resistance of the ballast resistor on our 300K at 0,6-0.7 Ohms on a 200 Ohm scale. FSM spec’s are 0.5-0.6 Ohms at 70F-80F. At 0.6 Ohms, it would take a 10 Amp current to the coil. Seems a little high. Nichrome resistance wire (if that’s what we have) Resistance and therefore, Voltage drop, increases with operating temperature. Over 90F in garage today. 102F outside at 5 PM, PDT.

Rich Barber in CA

From: 'John Cote' via Chrysler 300 Club International <chrysler-300-cl...@xxxxxxxxxxxxxxxx>
Sent: Monday, August 14, 2023 12:46 AM
To: Jean-Yves Chouinard <jym...@xxxxxxxxxxx>
Cc: Steve <sbe...@xxxxxxxxxxxxxxx>; Chrysler 300 Club International <chrysler-300-cl...@xxxxxxxxxxxxxxxx>
Subject: Re: {Chrysler 300} Trouble in F land.

From your symptoms, I would put my money in the ballast resistor on your firewall. Same happened in my ‘61 NYer wagon. Changed it and ran fine again. A much overlooked electrical item.
John
Sent from my iPhone

On Aug 14, 2023, at 12:05 AM, Jean-Yves Chouinard <jym...@xxxxxxxxxxx> wrote:

I would change the condenser in the distributor...as it was mentionned lately on a related thread, some are unreliable and work erratically...
JYves

From: chrysler-300-cl...@xxxxxxxxxxxxxxxx <chrysler-300-cl...@xxxxxxxxxxxxxxxx> on behalf of Steve <sbe...@xxxxxxxxxxxxxxx>
Sent: August 13, 2023 9:55 PM
To: Chrysler 300 Club International <chrysler-300-cl...@xxxxxxxxxxxxxxxx>
Subject: {Chrysler 300} Trouble in F land.

Hi 300 ites,
Problem with my F.
????
Ran the F last Sunday, ran great.55 to 70mph
Fueled up( 7 gals)
Came home and engine died.
Wants to fire but not.
Today,drained out all gas,new gas in, pumped and finally fired up. Ran 10 minutes, the rpms dropped.and died.
Cranking/ trying to fire but not starting. Pumps gas and spark is good blue.
Going to put new plugs in tomorrow and back to duel points.
Any thoughts,
Thanks in advance for your thoughts.
Steve Beard
300 F
Delaware,Ohio

Sent from my Verizon, Samsung Galaxy smartphone

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