1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Points and Condensers Failing

Discussion in 'Engine & Transmission' started by Mr Beckstar, Apr 23, 2019.

  1. Mr Beckstar

    Mr Beckstar Well-Known Member

    Messages:
    1,045
    Location:
    Bateau Bay, NSW
    any suggestions why I might be having regular issues with failing points and condensers?
    Harry stopped on the road yesterday driving back from Mallacoota. I had only checked the dwell the day before and it was a nice healthy 48 degrees. The points themselves were only a year old with about 2000 km on them. I suspect the condenser may have gone first and damaged the points. But the condenser was only brand new at the same time as I changed the points. And when I changed them last time, it was because my condenser had failed after only a thousand km and the points had serious build up on them.
     
  2. melissa

    melissa Administrator Staff Member

    Messages:
    14,876
    Location:
    Newcastle NSW
    I had trouble with points closing on my trip to Forbes - they were brand new as the engine had only just gone in - I think it's crap parts.
     
    BrianK and Mr Beckstar like this.
  3. Barry

    Barry Well-Known Member

    Messages:
    3,747
    Location:
    Abbotsford NSW
    I will 2nd that.

    I am not looking forward to points again when I get my bay.

    I think the first thing I will be getting is a 123 dizzy
     
    BrianK, Mr Beckstar and rstucke like this.
  4. rstucke

    rstucke Well-Known Member

    Messages:
    1,047
    Location:
    Wamberal NSW AUS
    check your primary resistance, any less than 3 1/2 ohms will result in a current flow that is too much for the points to handle across the contacts and they will burn
    the tungsten they are made of is not a good conductor

    Also you can apply the negative, negative, negative rule to determine if a condenser is too big or small for the job (should be 22uf. 300v)
    This means if you have negative material on the negative side (missing material on the earth side contact and a build up on the positive) then you have negative capacitance
    means condenser is too small. Opposite buildup on the contacts means condenser is too big.
    If the points are just burned the same means the contacts can't handle the current across them, back to not enough primary resistance
     
    Mordred, David H, cbus and 1 other person like this.
  5. rstucke

    rstucke Well-Known Member

    Messages:
    1,047
    Location:
    Wamberal NSW AUS

    I've got a 123 in Blitz and also carry a 009 dizzy and coil set up ready to drop in when the electronics die.
    difference between a tilt tray and a fix on the side of the road like Chris has achieved
     
  6. Grantus

    Grantus Well-Known Member

    Messages:
    15,865
    Location:
    Southern ACT
    Or just sell the bay real quick....... ;)



    Excellent to finally meet you today. Thanks for stopping by! :)
     
    Mr Beckstar and Barry like this.
  7. David H

    David H Well-Known Member

    Messages:
    5,007
    Location:
    newcastle
    Do these have a 'ballast' anywhere in the ignition system to handle the extras the condenser can't:confused:?
    Cheers
     
    Mr Beckstar likes this.
  8. Mr Beckstar

    Mr Beckstar Well-Known Member

    Messages:
    1,045
    Location:
    Bateau Bay, NSW
    I’ve got plenty of ballast in the front seat. Does that count? :confused:
     
    oldman and Wayne murray like this.
  9. David H

    David H Well-Known Member

    Messages:
    5,007
    Location:
    newcastle
    No it doesn't;). I seem to remember there is something ancillary to extra 'non dissipated' electrical energy:confused:.
    Cheers
     
    Mr Beckstar likes this.
  10. David H

    David H Well-Known Member

    Messages:
    5,007
    Location:
    newcastle
    So again... is this about where the 'extra energy goes?'
    Cheers
     
    Mr Beckstar likes this.
  11. Mr Beckstar

    Mr Beckstar Well-Known Member

    Messages:
    1,045
    Location:
    Bateau Bay, NSW
    I can’t actually see anything wrong with the removed points other than a small amount of material on the contact surface. I tested resistance at 0.1 ohm. But there’s no doubt Harry wouldn’t go when that set of points was installed.

    First, I put a whole dizzy in in place of mine as supplied by @Mordred. Started fine. Removed and swapped condenser with my dizzy and reinstalled my dizzy. Wouldn’t run right. Changed points on my dizzy and away he went.

    Many thanks to @Mordred for the assistance too. He saved me much cursing at my dizzy cap as the new oil pressure sensor post makes it hard to install the rear clip. I don’t think that’s related to the issue though.
     
    Mordred and David H like this.
  12. Mr Beckstar

    Mr Beckstar Well-Known Member

    Messages:
    1,045
    Location:
    Bateau Bay, NSW
    Primary circuit is 12V through coil, through points with condenser parallel and both to earth.

    Secondary circuit uses positive on coil but then goes through coil to high tension lead to centre of dizzy, through rotor button and off to each spark plug as points make primary circuit current/magnetic field collapse.
     
    Mordred likes this.
  13. David H

    David H Well-Known Member

    Messages:
    5,007
    Location:
    newcastle
    Still asking about 'ballast':confused:? Taking spare bits from all the electrickery?
    Cheers
     
    Mr Beckstar likes this.
  14. Mr Beckstar

    Mr Beckstar Well-Known Member

    Messages:
    1,045
    Location:
    Bateau Bay, NSW
    You may be referring to a ballast resistor which is an old/crude method of attempting to protect the primary circuit from too much voltage drop especially when cranking the motor. Harry does not have a ballast resistor and that’s normal.
     
    David H likes this.
  15. rstucke

    rstucke Well-Known Member

    Messages:
    1,047
    Location:
    Wamberal NSW AUS
    doesn't work that way
    the condenser reduces arcing at the points by absorbing some current flow for a very short time period till the points are far enough apart, this reduces burning across the contacts.
    it also sets up a ringing circuit with the coil that can be observed on an oscilloscope
    The ballast resister (nichrome wire either in a ceramic block or part of the wiring loom) found in some ignition systems (not vw) is used with a coil that has a resistance of 1.5 ohms the ballast is also 1.5 ohms when 12v is applied and hot. As engine rpm gets up there the amount of current through the resister reduces cools a little which reduces the resistance ergo increasing the current flow in the primary relative to a system that does not use a ballast.

    So the ballast controls the current at idle and lets more current through at high engine speeds. In reality its still less than at idle but more than the current flow through a system that only uses a coil. This in turn creates a stronger spark at higher engine speeds. The lower resistance coil in the ballast system means the coil saturates faster (builds up its magnetic field), good for a ballast system but destructive to the points in a non ballast system.
    Another advantage of the ballast system is that it can be bypassed while cranking the engine delivering a higher voltage for quicker starting. This is achieved by an extra terminal on the ignition switch or a terminal on the solenoid of the starer

    the 2 types of coil are not interchangeable and caused a few problems back in the day.
     
    oldman, Mordred and Mr Beckstar like this.
  16. David H

    David H Well-Known Member

    Messages:
    5,007
    Location:
    newcastle
    OK. So
    You're experiencing the opposite. Being too much voltage thru the circuit. Aside from condenser & coil where can any other 'spare' energy go?
    Cheers
     
    Mr Beckstar likes this.
  17. David H

    David H Well-Known Member

    Messages:
    5,007
    Location:
    newcastle
    Thanks Rick;). I sorta get it:).
    What are these? & what's burning the rotational bits (points) & why is there not something to take the spare energy as obv the condenser can't???
    Are we back to 'earths'?
    Cheers
     
    Last edited: Apr 23, 2019
    Mr Beckstar likes this.
  18. rstucke

    rstucke Well-Known Member

    Messages:
    1,047
    Location:
    Wamberal NSW AUS
    David
    The ringing part of the circuit is the interaction between the condenser and the coil. This is how the energy is dissipated.
    the condenser is like a small tank. It can accept a small amount of electrons (current) long enough until the points are open far enough to reduce arcing.
    When full the condenser bounces the electrons back at the same potential (voltage/pressure), the primary of the coil is what it bounces the current into. The coil accepts the energy and then throws it back into the condenser. This happens about 7 times and while this is happening there is a spark (high voltage) across the spark plug (aprox .8 to 1 milli seconds).



    primary.jpg

    When there isn't enough energy to keep the spark going the remainder is just used up by swaying back and forward between the coil and condenser (dissipated as heat)
    This should oscillate about 5 times.
     
    David H and Mr Beckstar like this.
  19. rstucke

    rstucke Well-Known Member

    Messages:
    1,047
    Location:
    Wamberal NSW AUS
    here's the pattern as seen from the secondary point of view

    fuel.jpg

    The spike up front is the pressure (voltage required to start the spark across the sparkplug gap
    the spark line the amount of time the spark fires for which is the amount of time the condenser and coil interact until there's not enough energy to keep the spark going.

    And you thought a Kettering ignition system was simple
     
    Mordred and Mr Beckstar like this.
  20. David H

    David H Well-Known Member

    Messages:
    5,007
    Location:
    newcastle
    Thanks Rick:). And here I was just thinking it made it go bang easily:(.
     
    Mr Beckstar likes this.

Share This Page