Pertronics help

Discussion in '1955-1959' started by dorcutt, Feb 3, 2020.

  1. dorcutt

    dorcutt Member

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    I installed the Pertronics ignition system this week end and can’t get the 57 to run well at all. This is the third vehicle I have installed a Pertronics system and haven’t had any issues in the past. Hooked up the red wire to the hot side of the resistor per their instructions so it should be good.
    The truck wants to run but is hard starting and acts like the timing is off when it does run. I re-gaped the plugs to .40 th per the suggestions here. Timing is going to be tricky as I have an automatic in it so I don’t have the typical fly wheel and BB to look at.
    An oddity is it try’s to start when I release the key from start position. I don’t recall that before.
    I did run it with the before I put the Pertronics in and it was running fine.
    I have tried moving the distributor to see if I can get it to run any smoother and have probably messed it up worse.
    Looking for any suggestions. Dave. Thanks.
     
  2. Bill Hanlon

    Bill Hanlon Member

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    Stock ignition wiring puts 12v to the non-coil side of the ballast resistor when the key is in the "run" position and 12v to coil side of the resistor (via the R terminal on the solenoid and a light green 18 gauge wire to the coil +) when the key is in the "start" position. I'm guessing you have no volts in the start position. As a temporary troubleshooting step, remove the Pertronics "red wire" to battery + and see if starting improves. You'll have to remove the wire to stop the engine.

    You could use a piston stop to determine TDC and the maybe mark the damper.
     
  3. dorcutt

    dorcutt Member

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    As always thanks for your input Bill. I will try your suggestion, I’ve been puzzled as to why it doesn’t have 12 volts all the time regardless of whether the ignition switch is in start or run position. I have been working on the wiring so I’ve got something crossed there I suspect.
     
  4. dorcutt

    dorcutt Member

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    Bill, a stupid question please, where does the coil get it’s power from in the start position. What I mean is the ignition switch provides power to the purple terminal on the starter solenoid to energize it. I have two green wires on the other small terminal on the solenoid where one wire goes to the coil and the other goes to the resistor. Is there a contact in the solenoid that closes to provide power from the purple small terminal to the small terminal with the two green wires.? I understand that when the ignition switch goes to the run position I get power on the brown wire, (ign 1) that feeds the resistor. I hope I explained myself well.
    I have not had a chance to get to the truck to confirm what happens when I hook up the Pertronics direct to the battery.
    Thanks for your patience.
     
  5. Bill Hanlon

    Bill Hanlon Member

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    Clipboard01.jpg

    I've copied the schematic from the 1957 GMC Maintenance Manual and then deleted a bunch of the superfluous stuff not important to this discussion. Then I changed the wiring colors to what they originally were.

    When the key is turned to the start position 12Volts from the BAT terminal on the ignition switch (red wire) is connected to the START terminal on the ignition switch (purple wire) .

    That puts 12Volts on the S terminal on the solenoid. Three actions happen.
    1. The solenoid plunger "pulls in". This physical motion engages the starter drive gear (the "Bendix") to the flywheel.
    2. The contactor inside the solenoid jumps the BAT terminal on the solenoid to the large terminal on the solenoid that goes to the starter motor and makes the starter motor turn.
    3. That same contactor touches the R terminal, providing 12Volts to the R terminal on the solenoid and out onto the green wire.

    The voltage in the green wire is sent to the Coil+ terminal where it is used to provide 12Volts to generate spark.

    The engine is spinning and hopefully starts.

    You let go of the key, which is spring loaded back to the "run" position, removing 12Volts from the purple wire. Three actions happen.
    1. The solenoid plunger "pulls out". This physical motion disengages the starter drive (the "Bendix") from the flywheel.
    2. The contactor inside the solenoid disconnects the BAT terminal on the solenoid from the large terminal on the solenoid that goes to the starter motor and lets the starter motor stop turning.
    3. The contactor disconnects from the R terminal, removing 12Volts from the green wire and the Coil+ terminal.

    Because the ignition switch is in the run position 12Volts is applied to the RUN terminal on the ignition switch and through the pink wire to the "hot" side of the ignition ("ballast") resistor. It passes through the resistor and comes out the other side at a reduced value. It connects to the Coil+ terminal. The engine is still spinning and hopefully will continue to run. How much voltage is available on the Coil+ terminal depends on how you measure it. The most accurate measurement would be with an oscilloscope which would show that when the points are open the Coil+ terminal would have something around 13.5Volts and when the points are closed the voltage on Coil+ would be around 8Volts. An analog voltmeter would average the reading at around 9Volts. A digital voltmeter would likely jump back and forth between the two readings.

    I don't know why there are two green wires from the R terminal on the solenoid. Originally there was only one, going to Coil+ (or the "cold" side of the ballast resistor). The way the second green wire is currently installed has the effect of shorting across the ballast resistor, removing it from the circuit. Maybe it is a requirement for the Pertronics unit. The net effect would be that Coil+ should have 12Volts on it when the ignition switch was in either "Run" or "Start".
     
    Last edited: Feb 6, 2020
  6. dorcutt

    dorcutt Member

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    Bill, many thanks and thank you for taking the time to draw out the schematic. You’ve confirmed what I thought and did a far better job of explaining it then I could of. My truck is wired as you indicate but will try to hard wire the Pertronics to the battery when I get on it again.
    I’m beginning to think I may have a starter solenoid problem as the power may not be transferring over to the R terminal when I’m starting it. I also suspect I have got the timing off in fiddling with it so will try to time it statically first and see what happens.
    I really appreciate you responding and hope I haven’t worn my welcome out.
     
  7. Bill Hanlon

    Bill Hanlon Member

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    You may be correct about the R terminal not getting 12Volts when the solenoid is pulled in. I'd take the end of the solenoid off and look. A little emery cloth and maybe a bending of the wiper that connects the contactor to the R terminal may fix it right up.
     
  8. vwnate1

    vwnate1 Member

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    FWIW, make sure which Pertronix you bought ~ some are designed to run on 8 VDC,others require a full 12 VDC, it depends on the application you chose when ordering, the wrong one will fry pretty quickly .

    As far as timing, once you get it running (take the solenoid apart and hand polish (DO NOT SAND/FILE/ABRADE ! #eek#) every contact inside it then re test the various connections before you connect the wires, then (and only then) connect a vacuum gauge (typically a $5 pawn shop / thrift store item, says 'vacuum gauge / fuel pump tester' on the dial) directly to the intake manifold and once the engine is full warmed up and idling, S_L_O_W_L_Y_ rotate the distributor by the body, NOT the vacuum advance whilst keeping a sharp eye on the gauge's needle ~ you want to keep turning as the needle rises, eventually it will begin to twitch ~ STOP and back up the turning until the gauge's needle registers the highest, steady reading, it should be between 15" ~ 21".

    If the needle twitches mercilessly, stop and go re adjust the valves again, try it again, should be fine .

    ? Still twitches ? you have the plug wires crossed .

    Remember, it's just like Women : 15, 36, 24 =:cool: .
     
  9. dorcutt

    dorcutt Member

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    Thanks Nate. I went to Pertronics and ordered the unit they recommended for my truck, 1168LA I think. I will look at the contacts as I found that I’m missing voltage on the terminal about 20% of the time which is indicative of dirty contacts. For years working in electronics I have used a pencil erasure for clean contacts with good success.
    The truck is like a woman and I still haven’t figured those out yet at this late stage in life. Thanks for weighing in.
     
  10. vwnate1

    vwnate1 Member

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    Yes well;

    The woman thing, you're on your own there #tongue# .

    I'm a geezer who doesn't ken them but managed to land a good one .

    The deal with Pertronics and every other modern electrical add on is : they told you to use this particular one for a 1957 Chevy truck that had a ballasted ignition, I'm not there with my meters and so on to discern what it actually needs, after sixty three years I'd expect someone made changes along the line .

    Yes the pencil eraser was a handy on hand shop tool / short cut but your rig is over 60 years old now so me, I'd only do the polish thing, folks always ask me how my 6 volt headlights are white and not yellow.....

    Maybe run a simple cube relay to feed the ignition ? .

    I did this on my 1969 Chevy C10 when I upgraded the breaker points distributor to a junkyard 1976 Nova one (cheaper and I prefer stock whenever I can get it) , the 8 VDC power feed easily clicks the $3 cube relay, they're typically designed to carry 30 amperes minimum so I'm not orred about it ever crapping out....

    Keep at it, I bet you just taking the current resistive ignition switch apart and polishing the contacts will set you right .
     

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