Re: [Chrysler300] Surprising source of miss in 300 ?
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Re: [Chrysler300] Surprising source of miss in 300 ?



John is right (as always) that strange wiring mistakes can be found on our 
old beasts!  Just another anecdotal example, on my J some previous owner 
genius had managed to switch the wires to the A/C resistor with the wires 
that go to the ballast resistor.  Yes, they are both resistors but not the 
same resistance.  Might have explained why my J had burned up points and 
barely ran, but it could have been the worn wiring connecting the capacitor 
too.  Regardless, it took a few years before I discovered the resistor 
problem and I also installed a Pertronix rather than mess with dual points. 
After I got the Pertronix to work (took awhile, a story in itself) the car 
ran great.  No further problems.  Just about anything can be screwed up on 
theses old beasts.

Carl B.
300J

From: 'John Grady' jkg@xxxxxxxxxxxxxxxxx [Chrysler300]
Sent: Friday, March 04, 2016 1:36 PM
To: 'Michael Moore'
Cc: Chrysler300@xxxxxxxxxxxxxxx
Subject: RE: [Chrysler300] Surprising source of miss in 300 ?




Hi Mike, A bad ballast resistor would stop you ---not burn the points. 
Remember Darts that start , and then stall immediately when you release key? 
Ballast. I believe you may possibly have a wiring mistake at the ballast 
where the feed to the coil is taken on the 12v side, or something like that 
.Check all connections , colors of wires at and around ballast and on back 
of key and at coil, to factory wiring diagram. It will sort of work with 10 
different mistakes..particularly confusing on these cars is Chrysler's start 
system, which kills ignition loads at crank except for a new feed --only 
during crank ---you get from the second S terminal (or sometimes another 
relay contact on the starter relay) ------that allows the car to start while 
the normal ignition power wire feeding the ballast is dead, zero v or very 
low (it back feeds some though ballast into ign power wire ) . I think they 
did this so all other loads go off during crank (ac, radio, heat fan etc) , 
but then it would not catch as there is no main ign power, by 
design --unless the 12V is supplied..they supply it directly to the coil, 
bypassing the ballast during crank from that second S terminal on key , You 
cannot do it with the same S terminal as the starter, or else ballast volts 
normally there running will pull in the starter relay all the time the ign 
is on.

This whole thing can drive you crazy and is not well explained . I only know 
about it after suffering with two swapped wires on a Dart key switch. Plug 
had melted someone made up individual wires then put them on, swapping 
two...long story, not for here. Car ran.

While idling you should have like 5-6 V at coil input side w average meter 
, ---or at least , less than the 12V (varies w RPM dwell etc) , if wiring 
right..

If not that wiring issue, burned points also immediately says bad capacitor, 
especially if a "new one". If it has stamped indented lines in can end , 
opposite end from the wire going in, it is Chinese junk. Get an old one, 
check it, put in . Car will barely run with no capacitor or an open one, 
spark extremely weak and arcing points at break. . It will however run OK 
initially with 12V on coil (the wiring error) --- but eventually burn 
points.

Dwell going UP (if that is correct data) is points way set too close , Mike 
...Burning , you would expect an opening up, Dwell drop, unless cam rub 
block is rubbing down? And so not opening them. Look at the mechanical 
action with the cap off... There is chance points were set too close, does 
not matter who did it, did not open enough, they arc across and burn. Or 
same thing caused by open capacitor. I had mentioned in an earlier email how 
critical that setting process is ,and hard to get perfect.

Sounds like bad cap..They are intermittent too. Adds to the fun.

-----Original Message-----
From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On 
Behalf Of Michael Moore mmoore8425@xxxxxxx [Chrysler300]
Sent: Friday, March 04, 2016 9:55 AM
To: Mike Moore
Cc: Chrysler300@xxxxxxxxxxxxxxx
Subject: [Chrysler300] Surprising source of miss in 300 ?

I have been trying to eliminate a miss in my 300H.

In the ongoing effort, I have replaced the damper, installed a Philbin 
rebuilt distributor, new plug wires, new plugs, carbs “restored”, coil 
replaced etc. with no improvement. Even 108 octane gasoline hasn’t helped.

I made arrangements for a visit to a great shop with a Sun engine analyzer 
(equivalent) , but I had to get it running reliably enough to get down 
there, and it now ran worse each time I started it.

Judging the problem to be ignition related versus carbs, I decided to strip 
and replace the entire ignition apparatus from ballast resistor through 
plugs. I ordered NOS Champion J-12Y plugs (which have always worked well for 
me), a new set of ignition cables (which are the best I have seen), a new 
coil, correct Mopar points, and new capacitor.

I began with a new correct ballast resistor and noticed the old ballast 
resistor ceramic wire wound resistor inside was broken into two pieces. As I 
hadn’t disassembled the rest of the system, I started the car with the new 
ballast resistor with no improvement, so I incorrectly dismissed that as the 
source of my miss.

While waiting for my original new parts to arrive, and after doing a 
thorough (165# on all 8) compression check (because all the plugs were out, 
front wheels were off and access was so easy), I disassembled the points 
from the distributor last night.

I found them badly burned! Aha!

My earlier distributor trouble shooting was to check only the dwell angle 
since it had recently been rebuilt. I noted the dwell angle had increased to 
45 degrees since I installed the distributor when it came back from Philbin.

I now believe what happened was that the ballast resistor failed sometime in 
past years, allowing the points to burn because of the higher than specified 
voltage on the coil. In recent years I haven’t driven the car much, but have 
changed the points entirely too often and haven’t noticed it too much 
because although it might be only 1500 miles, it may have been 3 years. I am 
certainly anxious to get it back together.

Thanks for all the help on line and off.
Mike Moore
300H

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Posted by: Michael Moore <mmoore8425@xxxxxxx>
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Posted by: "C Bilter" <cbilter@xxxxxxxxx>
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