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How long will a set of "hot" points last...

bandit67

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Guys, getting close to doing a cam break-in on my freshly rebuilt 440 and got to wondering how long has anyone ran a set of points at 12-13 volts before you began to notice engine run degradation to severe misfireing. Just curious , how long can they take the heat......
 
I assume it would cook the condenser fairly quickly, never done it with a stock coil
 
The points and condenser do not care what voltage they are switching. It is all in the windings of the coil.
 
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I wouldn't bypass the ballast, it's there for a reason.
There is nothing to be gained.
Timing is more important I suggest leaving the plugs out, priming the oil pump and cranking it with a timing light to set it.
Install the plugs and it will fire immediately.
 
New points will be OK for a while on 12 volts. This is dependant - but a guess is a few months.
As stated previous it is the primary coil windings that will determine this. The condenser is only a capacitor to allow the voltage to build up for when the points open.
The severe arcing will eventually fry the points.
Should certainly be OK for cam break in.
 
Plan is to use the stock coil for break in. I know all the old Chevies had a bypass wire from the starter to the coil to provide 12-13 volts to the coil while the starter was cranking...just assumed Mopars did also. I assumed this provided a greater spark to get her fired up.
 
yes there is a bypass feed from ignition switch on cranking for higher voltage
 
Good points about the ballast resistor need, and its advantages over the resistor wire used on Phords and Chebbbys

 
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And about the resistor bypass... as mentioned, Chrysler also made it from ign switch up to 75/76. While cranking, a brown wire coming out from ign switch splices into the coil + lead wire arriving to ballast. The coil wire was blue up to 69 and became brown since 70 to not mix it up with the new blue wire arriving to alt field when charging system become on "dual field" system which is related with the run circuit.

Since 75/76 ( split year because change was made diff depending on bodies changes ) the ballast bypass was made from starter relay instead ign switch. These starter relays are of course diff from earliers to get this source offered.
 
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Thanks Nacho, I just assumed the resistor bypass would have been for points only and would NOT be on the "new" electronic ignition system that started in or around 1973 I think.

Was not aware , as Tony pointed out , that the ballast resistor was variable,hmmmmnnnnn. And now understand WHY the duel ballast was used on the electronic systems....Good Vid, thanks Nacho
 
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Welllllll, the ballast isn't really variable... in that case it would be called a variable resistor. Which its not. resistance just changes with heat and load. Like everything else.
 
Just more sensitive which makes it work for its final purpouse
 
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Welllllll, the ballast isn't really variable... in that case it would be called a variable resistor. Which its not. resistance just changes with heat and load. Like everything else.
The Mopar Ballast resistor has POSITIVE TEMPERATURE COEFFICIENT properties thst means its resistance changes as the current flow increases to try and maintain a uniform voltage drop. This is accomplished by using a NI-CHROME IRON composition resistance wire....which makes it a variable resistor. The ballast resistor limits the current flow to the coil's primary winding, to prevent over heating and excessive arcing at the points when they close.
The purpose of the condenser is to absorb the coil's primary winding's induced voltage (+200 volts), when the points open, which at the same time, generates the high voltage in the coil's secondary windings. The capacitor's capacitive reactance matches the coil's primary inductive reactance to allow for the coil's smooth charge-discharge time constraints. The coil is constructed as an auto-transformer.
The ballast resistor is usually bypassed during cranking to provide full battery voltage to the ignition system to provide the hottest spark. Battery voltage during cranking drops to 9.5 - 10.5 volts due to the 400 - 500 amps the starter motor draws, especially in cold weather and thick oil or high compression.
And once again, good old Nacho-74RT is only 50% correct in his "explanation"....so believe what you want....
BOB RENTON
 
Ohh... sorry... I misread the title of this thread. I thought it was HOT PANTS. My answer was " not long" .......
 
I was to post about the NiChrome wire wound built into the ballast ( same wire used on bread toasters ), but just didn't go to get deeper into that. So please read correctly my post:

Even I know how the ballast resistor works I didn't say anything about the resistor value variation or how it works, just told HOW IT WAS BYPASSED BY CHRYSLER, diff from Phords and Chebbys... but Uncle Tony did.

( once again, because is not uncommon you put words in my post I never did )
 
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I was to post about the NiChrome wire wound built into the ballast ( same wire used on bread toasters ), but just didn't go to get deeper into that. So please read correctly my post:

Even I know how the ballast resistor works I didn't say anything about the resistor value variation or how it works, just told how it was bypassed by Chrysler, diff from Phords and Chebbys... but Uncle Tony did.

( once again, because is not uncommon you put words in my post I never did )

Get it right the first time....only achievable thru fundamental knowledge of the subject....not thru guesses or suppositions based on hearsay or your 74RT (which is not the center of the automotive universe). I'm not adding anything to your posts....other than pointing out your lack of specific knowledge or information. PM me if you want to discuss further.
BOB RENTON
 
I'm just wondering where I said anything about how it works the ballast resistor to be "corrected" ( if really required ) about that? I can't find anything on my post saying anything about that. I just wrotte about how it is bypassed from factory.

Period
 
Variable resistor
Chapter 3 - Resistor types
What is a variable resistor?

A variable resistor is a resistor of which the electric resistance value can be adjusted. A variable resistor is in essence an electro-mechanical transducer and normally works by sliding a contact (wiper) over a resistive element. When a variable resistor is used as a potential divider by using 3 terminals it is called a potentiometer. When only two terminals are used, it functions as a variable resistance and is called a rheostat. Electronically controlled variable resistors exist, which can be controlled electronically instead of by mechanical action. These resistors are called digital potentiometers.

Variable resistor definition
A resistor of which the ohmic resistance value can be adjusted. Either mechanically (potentiometer, rheostat) or electronically (digital potentiometer).
Types of variable resistors
Potentiometer
potentiometer_100px.jpg
The potentiometer is the most common variable resistor. It functions as a potential divider and is used to generate a voltage signal depending on the position of the potentiometer. This signal can be used for a very wide variety of applications including: Amplifier gain control(audio volume), measurement of distance or angles, tuning of circuits and much more. When variable resistors are used to tune or calibrate a circuit or application, trimmer potentiometers or trimpotsare used, this are mostly small potentiometers mounted on the circuit board, which can be adjusted using a screwdriver.

Rheostat
rheostat_rotary_100px.jpg
Rheostats are very similar in construction to potentiometers, but are not used as a potential divider, but as a variable resistance. They use only 2 terminals instead of the 3 terminals potentiometers use. One connection is made at one end of the resistive element, the other at the wiper of the variable resistor. In the past rheostats were used as power control devices in series with the load, such as a light bulb. Nowadays rheostats are not used as power control anymore as this is an inefficient method. For power control, rheostats are replaced by more efficient switching electronics. Preset variable resistors, wired as rheostats are used in circuits to perform tuning or calibration.

Digital resistor
digital-potentiometer_100px.jpg
A digital variable resistor is a type of variable resistor where the change of resistance is not performed by mechanical movement but by electronic signals. They can change resistance in discrete steps and are often controlled by digital protocols such as I2C or by simple up/down signals.

Symbols for variable resistors




potentiometer-symbol.png
Potentiometer symbolIEC standard
rheostat-symbol.png
Rheostat symbolIEC standard
preset-resistor-symbol.png
Preset resistor symbolIEC standard
 
RJ- this is what I meant by my post. I do see what you are saying, and agree,,, its just the term "variable". I read that as something one can vary. Electrical things vary with heat, so we could say that all electrical things/components are variable.
 
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