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Thread: 51 M38 - over my head

  1. #31
    Super Moderator bmorgil's Avatar
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    Will, are you using a voltmeter or a light bulb to set the timing? If you are and you see the correct voltage across the points when they are open, everything is good all the way to the coil as far as power goes. You should not see an arc. The purpose of the condenser is to prevent the arc when the points open. Going to the basics here, when the points close the coil is energized. As soon as the points open the charged coil discharges through the center electrode to the distributor cap. From there through the rotor to the plug. So if you have the correct voltage across the points when they are open, you can eliminate a lot of things.

  2. #32
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    thanks!
    I am use a light bulb and I do see an arc - so dose that mean I need to repalce the condenser?

    that is a new rebuilt distributor - but I guess that dosen't mean the condenser is good

  3. #33
    Super Moderator bmorgil's Avatar
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    Does the light bulb light when the points open? If so you have voltage to the coil. The condenser (though it could be bad) is very seldom "bad". Unless it is shorted, the motor will usually run. Miss-firing and general bad running is the symptom. The points will be badly pitted and "burned" when the condenser is bad. Now if you have power to the coil, the light lights when the points are open, the Coil, Coil Wire and the Distributor cap become suspect. High primary coil current could also cause an arc accost the points. This can occur if the primary coils are shorted in the coil.
    Last edited by bmorgil; 03-13-2020 at 04:02 PM.

  4. #34
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    Thanks - big time! I am learning -
    so I belive this is a matter of the gap being to small and timing
    see photos - showing power going to the coil when gaps are open and not when closed - new concept for me -
    so I believe I need to set the gap
    then the rotor is turned to clynder #4 plug at what I think is TDC based on pencil method
    my understanding is the gap should just start to open after passining TDC (top dead center)
    this is all new to me - so if I have this wrong let me know

    I really appreciate this!!IMG_3720.jpgIMG_3721.jpgIMG_3722.jpgIMG_3723.jpgIMG_3724.jpg
    best will

  5. #35
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    I did check the gap - .02 inch - at the most open spot

  6. #36
    Super Moderator bmorgil's Avatar
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    You are correct Will. The points when closed, close the circuit to ground and energize the coil. The instant the points open the coil is saturated with current and has to discharge. It discharges the high secondary voltage build up through the coil wire. You set the point gap first, it will affect the timing. Then you align the timing mark on the flywheel with the number one cylinder at TDC, and the valves closed on the compression stroke. Rotate the engine (a helper is good here) with your thumb over the spark plug hole on number one cylinder. When you feel the air from the compression stroke leaking past your thumb, watch for the timing marks. Align the mark on the motor to the 5 deg BTDC line on the flywheel. Rotate the distributor very slowly and watch the points and the light. The instant the light lights, there is fire to whichever wire on the cap the rotor is pointing to. That is number one. Tighten the distributor down, it is now timed to fire number one, at 5 degrees before TDC. Hopefully number one is where you want it to be. If not, it makes no difference. Just follow the firing order around from there.

    If this all went well and there is no spark, I would suspect the coil, coil wire or distributor cap.
    Last edited by bmorgil; 03-14-2020 at 05:19 PM.

  7. #37
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    Set the point gap about the thickness of a match book.

  8. #38
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    thanks guys!

    I belive the gap at .02 is to small - going to go up to .03 and try the timing advice

    I will report back -
    thanks again!

  9. #39
    Super Moderator bmorgil's Avatar
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    The correct gap is .030".

  10. #40
    Super Moderator gmwillys's Avatar
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    A quick farmer's gauge would be a match book cover as okiemark stated. The match strike can also touch up the points in a pinch. Bmorgil is correct, 0.30" is the gap for the points.
    Last edited by gmwillys; 03-15-2020 at 05:51 PM.

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