As a mechanical engineer I say F=mA (Force = mass times acceleration. I gave up on electrumtrisity as a four-year old trying to plug the power cord of my Lionel train transformer into a wall socket. The worn blades of the plug would not line up with the slots in the wall and, being mechanically minded, I squoze them together with finger and thumb and jammed them into the receptacle. It bit me and I then picked my sorry four-year-old butt off the far wall and decided then and there to be a mechanical engineer rather than electrical. This discussion on point burning is like the old argument between major auto makers on positive vs. negative ground. Polarity defines the direction the spark flows at the spark plug—center electrode to ground or vice versa. With points, the arc will go one way or the other which we have seen many time on old points. The metal loss on one of the points will result in a conical buildup on the other. If low on pelf, one just filed the points smooth and kept on truckin’. In the end, any difference on polarity in automotive ignition systems is mostly theoretical with little, if any, measurable difference in lighting off the fuel-air charge in a cylinder at the right time. Having the electrode in the center of a hemispherical head of a Chrysler 300 hemi engine helped greatly. So much so that Chrysler now places two electrodes/sparkplugs in each cylinder of their present semi-hemi. I’d bet that at high DC currents and Voltages, the design polarity of contacts and circuit breakers is much more significant and warrants consideration of polarity. Back in the dry winter homes and hotels in the Midwest, one could also build up a considerable DC static charge while walking on synthetic carpet. The electrode became your outstretched finger or hand as you reached for a grounded door handle, light switch or any other good ground. One learned to spread out the discharge event over a larger area by advancing a metal door key to the door handle and have the key take the zap. Whether the direction of the arc was door to finger or vice-versa, the shock felt the same. As I recall, work =I²*R in a DC electrical circuit—and will be manifested as heat. In an arc, there is some work done in heating the air path and ionizing the air enough to conduct electricity. I’d think it would be the same in either direction, as would the arc or spark. That arc in the cylinder provides the heat necessary to light off the compressed fuel-air charge in the cylinder. I added at least one additional thing to check and that was the ground strap from block to firewall. Reading further, I also was reminded that the resistance of the Ballast Resistor will vary greatly with temperature. Current flow will heat up the NiChrome (maybe) wire coil inside the channel-shaped ceramic protective device. That channel is actually open at the back. I’m guessing that current flow will heat this resistor up pretty dramatically and that will result in even more Voltage drop to the run-wire to the coil. It is conceivable the ceramic enclosure could be broken without affecting the spiral-wound NiChrome (?) wire resistor—and it further explains why the once pearly-whit ceramic enclosure takes on the grubby appearance. Underhood fumes and particles are baked onto and into the surfaces of the ceramic enclosure. You asked what time it is and that’s how to build a watch. Sorry about that. Goes with the hat. I have learned a lot and reviewed a lot during this thread. Thanks for the broad participation. Rich Barber Brentwood, CA (Home of Chrysler 300’s, not Ford Bronco’s) From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of Ray Jones 1970hurst@xxxxxxxxx [Chrysler300]
Sent: Sunday, March 06, 2016 4:02 PM
To: Fern Rivard <crc@xxxxxxxxxxxx>
Cc: paul <paulholm@xxxxxxxxxxxxx>; Listsaver 300 Club <Chrysler300@xxxxxxxxxxxxxxx>; Ray Jones <1970hurst@xxxxxxxxx>
Subject: Re: [Chrysler300] Surprising source of miss in 300 ? Thanks Fern, but you miss the point. The difference is that the switch is just supplying a ground and there is no potential, or need to do work. Hard to explain, but that's the way my instructors put it,
Think of it as electric welding. Welding is just a dead short that you control, power (voltage) going to ground creating an arc, across a gap, which melts one metal into another to form a bond (weld). That is the maximum definition of potential, being used in a good way.
With power going into a switch, and then on to work and then ground, you create an arc, just as the switch is about to contact the terminal, it jumps across the gap, burning the contacts.
And I can testify that I never replaced any thing with contact points in it on Japanese cars. Not counting the early days of points in Dist. Not being an engineer, that's the way I understand it and practice seems to bear it out. What say you Rich? Yes or no? On Sun, Mar 6, 2016 at 5:30 PM, Fern Rivard <crc@xxxxxxxxxxxx> wrote: Hi Ray: It shouldn’t make any difference as you will be drawing the same amount of current thru the switch whether you are key the positive side or the negative side. The real way to prevent any arcing in the switches would be to have a relay carry the load current. I wouldn’t want to have the 12 volt positive sitting at my headlights waiting for the ground to turn them on. This is just looking for an accident to happen. I’m not a mechanic but have worked on electronics all of my life. Sent: Sunday, March 06, 2016 1:03 PM Subject: Re: [Chrysler300] Surprising source of miss in 300 ? This has nothing to do with the problem, but just some electric lore to digest. You mention arcing in the switches. In Japanese cars (worked on them most of my later career) the switches are switched negatively. We switch positively. So, what happens is "Potential" arcing. Electricity wants to do work, which is why a short is so bad, NO work. Even a little mini light bulb, drawing almost no current is work, so all is fine. So, when we turn a switch, just before the actual contact the current jumps across the space to go to work. This is an arc. Switched negativity, the work is already in the line so you are merely providing a ground to complete the circuit, no arc, work performed. In Japanese cars, testing circuits will drive American techs nuts, until they learn this basic fact. Even the head light bulbs will have the current going thru them, awaiting the switch to provide ground so they can light up (work), If you got this far, go to U-tube and Jay Leno's Garage and look up the Acura NSX video. Awesome car with unbelievable engineering, including separate electric motors for each front wheel and a Armature and field behind the flywheel to provide much more power. On Sun, Mar 6, 2016 at 1:04 PM, paul paulholm@xxxxxxxxxxxxx [Chrysler300] <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote: On 03/06/16 13:44, John Grady jkg@xxxxxxxxxxxxxxxxx [Chrysler300] wrote:
> Yes -- they punt you walk . Different kind of problem !!
> Sent from my iPhone
>> On Mar 4, 2016, at 5:13 PM, Michael Moore <mmoore8425@xxxxxxx>
>> wrote:
>> I was about so say I don’t like them because its too hard to
>> trouble shoot a problem based on my experience. But I wonlt say
>> that ! :-)) Mike Moore 300H On Mar 4, 2016, at 1:33 PM, David
>> Schwandt <finsruskw@xxxxxxxxxxxxxxx> wrote:
>> Have you considered going w/a Pertronix?? I did so 20 years ago
>> after distributor problems drove me crazy, some may say I still
>> am!!!
>> -----Original Message----- From: Chrysler300@xxxxxxxxxxxxxxx
>> [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of 'John Grady'
>> jkg@xxxxxxxxxxxxxxxxx [Chrysler300] Sent: Friday, March 04, 2016
>> 1:37 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.
snip
>> 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.
In the Telephone industry when they used electromechanical switching,
a serious butt load of relays, contact protection was berry berry
important. All most all ganged relays had a form of capacitor/resister
network on them to aid in controlling arcing, Necessary for long
contact material life. Replacing the contacts on wire spring relays was
a daunting task, usually once in use it was a task that was tried to be
avoided. Once that skill was mastered, the technician that could do it
would usually have a long list of switching centers to go replace
contacts, at least in my experience. (got several nice free lunches
doing that project)
YES, usually once contact wear became noticed, the first thing tried
was replacing the capacitor/resister network. ALTHO I can say that
since they were meant to work a long time, they generally were
not defective, ATT built to last the average lifetime of the hardware.
(No 'Made in China' back then)
If I recall rightly, some of the in use relays usually had an unused
contact pair set aside as a backup in case the working contacts burned
out.
--
--
Paul Holmgren
If you could sum up all you felt about life and crystallize
it in one master insight, you would have said it all, and
you would be dead - Fritz Leiber -
-- Ray Jones. Y'all come on down an see us. Ya hear?
--
Ray Jones. Y'all come on down an see us. Ya hear? __._,_.___
Posted by: "Rich Barber" <c300@xxxxxxx>
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