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

Electrical & Ignition

  1. bandit67

    bandit67 FBBO Gold Member FBBO Gold Member

    Messages:
    851
    Likes Received:
    1127
    Joined:
    Feb 29, 2020
    Location:
    South of the Mason Dixon line......
    Local Time:
    3:30 PM
    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......
     
    • Like Like x 1
    • pnora

      pnora FBBO Gold Member FBBO Gold Member

      Messages:
      746
      Likes Received:
      579
      Joined:
      Apr 21, 2020
      Location:
      Ishpeming, Mi.
      Local Time:
      3:30 PM
      Depends on the coil used.
       
      • Like Like x 1
      • Moparnocar

        Moparnocar Well-Known Member

        Messages:
        538
        Likes Received:
        253
        Joined:
        Jul 16, 2019
        Location:
        Mahtomedi
        Local Time:
        2:30 PM
        I assume it would cook the condenser fairly quickly, never done it with a stock coil
         
        • Like Like x 1
        • pnora

          pnora FBBO Gold Member FBBO Gold Member

          Messages:
          746
          Likes Received:
          579
          Joined:
          Apr 21, 2020
          Location:
          Ishpeming, Mi.
          Local Time:
          3:30 PM
          The points and condenser do not care what voltage they are switching. It is all in the windings of the coil.
           
          Last edited: Apr 20, 2021
          • Like Like x 1
          • Agree Agree x 1
          • Don Frelier

            Don Frelier FBBO Gold Member FBBO Gold Member

            Messages:
            3,935
            Likes Received:
            4437
            Joined:
            Oct 11, 2016
            Location:
            Ionia, NY
            Local Time:
            3:30 PM
            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.
             
            • Like Like x 3
            • Agree Agree x 1
            • steve340

              steve340 Well-Known Member

              Messages:
              718
              Likes Received:
              582
              Joined:
              Jul 7, 2018
              Location:
              New Zealand
              Local Time:
              7:30 AM
              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.
               
              • Like Like x 1
              • Thanks! Thanks! x 1
              • Agree Agree x 1
              • bandit67

                bandit67 FBBO Gold Member FBBO Gold Member

                Messages:
                851
                Likes Received:
                1127
                Joined:
                Feb 29, 2020
                Location:
                South of the Mason Dixon line......
                Local Time:
                3:30 PM
                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.
                 
              • bm02tj

                bm02tj Well-Known Member

                Messages:
                2,226
                Likes Received:
                3978
                Joined:
                Jan 27, 2013
                Location:
                BC Canada
                Local Time:
                12:30 PM
                yes there is a bypass feed from ignition switch on cranking for higher voltage
                 
                • Agree Agree x 1
                • Nacho-RT74

                  Nacho-RT74 FBBO Gold Member FBBO Gold Member

                  Messages:
                  4,583
                  Likes Received:
                  1556
                  Joined:
                  Oct 8, 2012
                  Location:
                  Valencia, España
                  Local Time:
                  9:30 PM
                  Good points about the ballast resistor need, and its advantages over the resistor wire used on Phords and Chebbbys

                   
                  Last edited: Apr 21, 2021
                • Nacho-RT74

                  Nacho-RT74 FBBO Gold Member FBBO Gold Member

                  Messages:
                  4,583
                  Likes Received:
                  1556
                  Joined:
                  Oct 8, 2012
                  Location:
                  Valencia, España
                  Local Time:
                  9:30 PM
                  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.
                   
                  Last edited: Apr 21, 2021
                  • Like Like x 1
                  • Thanks! Thanks! x 1
                  • bandit67

                    bandit67 FBBO Gold Member FBBO Gold Member

                    Messages:
                    851
                    Likes Received:
                    1127
                    Joined:
                    Feb 29, 2020
                    Location:
                    South of the Mason Dixon line......
                    Local Time:
                    3:30 PM
                    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
                     
                    Last edited: Apr 21, 2021
                  • RemCharger

                    RemCharger Well-Known Member

                    Messages:
                    470
                    Likes Received:
                    271
                    Joined:
                    Apr 5, 2014
                    Location:
                    Sask
                    Local Time:
                    2:30 PM
                    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.
                     
                  • Nacho-RT74

                    Nacho-RT74 FBBO Gold Member FBBO Gold Member

                    Messages:
                    4,583
                    Likes Received:
                    1556
                    Joined:
                    Oct 8, 2012
                    Location:
                    Valencia, España
                    Local Time:
                    9:30 PM
                    Just more sensitive which makes it work for its final purpouse
                     
                    Last edited: Apr 21, 2021
                  • RJRENTON

                    RJRENTON FBBO Gold Member FBBO Gold Member

                    Messages:
                    1,622
                    Likes Received:
                    1445
                    Joined:
                    Jul 1, 2015
                    Location:
                    South Shores area of Decatur, Illinois
                    Local Time:
                    2:30 PM
                    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
                     
                    • Thanks! Thanks! x 2
                    • WileERobby

                      WileERobby Well-Known Member

                      Messages:
                      7,227
                      Likes Received:
                      9150
                      Joined:
                      Sep 15, 2009
                      Location:
                      State of insanity
                      Local Time:
                      3:30 PM
                      Ohh... sorry... I misread the title of this thread. I thought it was HOT PANTS. My answer was " not long" .......
                       
                    • Nacho-RT74

                      Nacho-RT74 FBBO Gold Member FBBO Gold Member

                      Messages:
                      4,583
                      Likes Received:
                      1556
                      Joined:
                      Oct 8, 2012
                      Location:
                      Valencia, España
                      Local Time:
                      9:30 PM
                      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 )
                       
                      Last edited: Apr 22, 2021
                    • RJRENTON

                      RJRENTON FBBO Gold Member FBBO Gold Member

                      Messages:
                      1,622
                      Likes Received:
                      1445
                      Joined:
                      Jul 1, 2015
                      Location:
                      South Shores area of Decatur, Illinois
                      Local Time:
                      2:30 PM
                      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
                       
                    • Nacho-RT74

                      Nacho-RT74 FBBO Gold Member FBBO Gold Member

                      Messages:
                      4,583
                      Likes Received:
                      1556
                      Joined:
                      Oct 8, 2012
                      Location:
                      Valencia, España
                      Local Time:
                      9:30 PM
                      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
                       
                    • RemCharger

                      RemCharger Well-Known Member

                      Messages:
                      470
                      Likes Received:
                      271
                      Joined:
                      Apr 5, 2014
                      Location:
                      Sask
                      Local Time:
                      2:30 PM
                      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
                       
                    • RemCharger

                      RemCharger Well-Known Member

                      Messages:
                      470
                      Likes Received:
                      271
                      Joined:
                      Apr 5, 2014
                      Location:
                      Sask
                      Local Time:
                      2:30 PM
                      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.
                       
                    1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
                      By continuing to use this site, you are consenting to our use of cookies.