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Distributor and Primary / Secondary ignition Information

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  • Distributor and Primary / Secondary ignition Information

    Distributor Assembly Specifications


    Rotor Revolution Direction Counterclockwise

    Point Gap .018" to .022"

    Point Spring Tension 16 to 18 oz.

    Condenser Capacity .20 to .25 mfd

    Yellow Wire Ignition Circuit 12 gauge

    All Other Wiring (except high tension circuit) 16 gauge

    Camshaft to Bearing Clearance .001" to .002"

    Spark Control Manual Advance 20° (28° camshaft travel)

    Rotor End Cap to Distributor Terminal .020"

    Ignition Circuit .62 amps at 6.2 volts (engine at 1500 rpm)
    4 amps at 6.2 volts (engine stopped)

    Set point gap at .018"-.022" (.022" for new points). The rubbing block on the points will wear down .003"-.005" after approximately 400-1,000 miles. After this point, wear might only be .001" over the next 10,000 miles. Therefore, be sure to reset the point opening to .022" by the end of the first 1,000 miles.
    2 1930 Tudors

    Henry Ford said
    "It's all nuts and bolts"


    Mitch's Auto Service ctr

  • #2
    Beware of the wireless lower distributor plate

    Your best bet is to stay away from these wireless lower plates. They have been known to cause driveability issues at idle and also breaking up and back firing under load. Many of these problems are intermittent in nature and can drive you crazy. The original style plate with a good wire will give you a positive connection all the time.
    Just because it says modern does not mean it's better.


    Screenshot (6).jpg
    Attached Files
    2 1930 Tudors

    Henry Ford said
    "It's all nuts and bolts"


    Mitch's Auto Service ctr

    Comment


    • Mitch
      Mitch commented
      Editing a comment
      Armored cable clamp

      If the armored cable hold down clamp ever needs to be removed for any reason, first drain down the cooling system below the level of the cylinder head before removing the head nut. Otherwise you risk the chance of having coolant seep into the crank case (oil) and or into the cylinders which will cause liquid lock and possible engine damage if it is cranked over.



      IMG_6283.JPG
      Attached Files

    • Mitch
      Mitch commented
      Editing a comment
      Dist lower plate wire

      This pic from Marcos barnyard shows the correct bend on the lower plate flag terminal and the phenolic washer


    • Mitch
      Mitch commented
      Editing a comment
      I carry a spare distributor with me thats already timed and ready to drop in. It has an alligator clip on one end so i can connect it directly to the coil after removing the exsisting red wire that feeds the ignition switch. Another option is to unscrew the temporary cable / alligator clip assy and just use that if the distributor is ok. This will bypass everything from the dist to the coil incld the igniton switch since that feeds power to the dist..
      Attached Files

    • sphanna
      sphanna commented
      Editing a comment
      Emergency points setting tip

      original thread:
      https://www.vintagefordforum.com/for...al-style-point


      If your buddy's car starts to too run horrible and sounds like a gun fight at the OK corral because he has allowed his cam to wear the point block to where they barely open and he has no tools other than a small screw driver, here is a quick and accurate fix. Turn his engine to the high part of the cam. Now close the gap until the points just touch. Now open the points by screwing the screw to open by turning the screw 180* open. Then open it another 45* and you have .020 gap. This is easily done by naked eye. If you are a perfectionist (OCD) , the actual turn would be 230* open so that is 180* plus 50* but 45* is insignificant and extremely easy to estimate. Don't need a feeler gage or a match book for this and it is accurate.

      Steve

    • Mitch
      Mitch commented
      Editing a comment
      The Model A Ignition System 101, by Tom Wesenberg:

      Model A Ignition System


      The Model A ignition system consists of the battery, amp guage, ignition switch, coil, distributor, spark plugs, and wires connecting these parts. A failure in any part means no spark to the plugs.

      The coil always has 6 volts at the primary terminal and the coil is connected to the points when the ignition switch is turned on. The popout switch in the OFF position grounds the points, so the distributor contact on the popout cable should show continuity to ground and the coil terminal (by the key end) should show no continuity to anything. In the ON position the distributor contact should show continuity to the coil terminal, and neither terminal should show continuity to ground.

      Repro switches are simple OFF-ON single pole switches with no connection to ground. The main fault I find in repro switches is the contacts in the back of the switch are not a very positive contact and often don’t make a good connection.

      When the car doesn’t start, check the simple things first. Pull the coil wire from the cap and hold it ¼” from a head nut while cranking the engine with the key on. You should have a good blue spark. If you have a weak yellow spark check the points and condenser first. Condensers are very easy and quick to change if you follow these steps exactly.

      1. Have the new condenser laying next to the distributor.
      2. From the passenger side, remove the ground screw FIRST.
      3. From the driver’s side remove the condenser terminal screw and be sure to keep light pressure on the screw while you slip out the old condenser and slip in the new one.
      4. Tighten the terminal screw, then go to the passenger side and tighten the ground screw.

      Always set the points to .020” first, then set the timing. Remember that the points setting can affect the timing, but the timing can’t affect the points setting. Be sure to have lube on the points rubbing block. I always carry a small piece of sandpaper in my billfold just in case I need to clean points, or check an engine number at a swap meet, etc. A points file is good to keep in your car’s tool kit and only costs about a dollar. To check the function of the points, stop the engine with the points open and key ON, then short the points contacts off and on using a screwdriver. If this produces a good spark, then the points need to be cleaned. If you are getting no spark, but the coil is getting hot, then something is grounded between the points and coil, which keeps the coil turned on full time. Be sure to oil the distributor often.

      The Model A coil primary consists of 250 turns of # 20 enameled wire. The coil secondary consists of 16,000 turns of #38 enameled wire. The condenser is .3 mf.* See page 390 in the SERVICE BULLETINS for a change in the coil connections. 1928-9 coils have the negative terminal on the passenger side, while Nov. 1929 and later coils have the negative terminal on the driver’s side. Date codes can be found on the coil mounting bracket.

      When checking cylinders for power, it’s better to SHORT the spark plug, rather than to disconnect the plug wire. When the spark has no place to go it tries to find the easiest path to ground, which may be to jump internally inside the coil to the metal body, or arc at the coil tower.

      1928-9 slant pole coils have the metal case around the primary terminals, so make sure the first thing to go on the terminal studs is an INSULATING WASHER, then a flat washer, lock washer, and a hex nut. Barrel nuts are used to secure the wires to the slant pole coils. NO boots are used on the coil wire.

      To check coil polarity hold a pencil lead in the spark path with the plug wire about a third of an inch away from the distributor terminal. You’ll see a FLARE on one side of the pencil lead and this flare should be on the spark plug side of the lead. If you do a Google search on “COIL POLARITY”, CHICAGOLAND MG CLUB has an excellent short article about checking spark plug polarity and why it’s important. Check:
      http://www.chicagolandmgclub.com/tec...neral/574.html

      * Thanks to Vince Falter for the coil and condenser information.

      This is the sheet of notes I handed out last night at our club clinic when I gave a talk about the ignition system. This applies to the original ignition system and parts. More notes can be added, especially for after market parts, such as: some aftermarket coils are oil filled and must be mounted with the tower facing UP.

      Feel free to add to the list of notes if you can think of something I missed.

    • Mitch
      Mitch commented
      Editing a comment

    • plyfor
      plyfor commented
      Editing a comment
      Thanks for posting this info. By chance propably for the thicker clamp, we had a longer head stud at the cable hold down clamp, and with a very thin nut,was able to attach the later clamp over the head stud nut without changing the head nut torque.

  • #3
    The V8 condensors you buy today may not be the best quality even if they are major name brand. People on the Mustang boards have complained of failures out of the box. I work in electronics and the problem is in the sourcing from overseas sources. They do not always used the best chemistry in the separator. There is a thin 'paper' between two pieces of foil. That is wet in the electrolytic capacitor. Dell computer got caught up when a manufacturer stole a formula and they did not get all the ingredients.

    It is recommended that you get the A&L blow out proof condenser for reliablility. These are available from all the major suppliers. My brother and many other people find they get decades of use out of these condensers. No heat shield needed.

    Comment


    • #4
      Ignition System Basics

      A special thanks to Paul Modlin

      http://modelabasics.com/Ignition.htm


      Special thanks to Tom Wesenberg for his tips on checking Coil Polarity and Installing the Condenser properly.
      Inspection:
      When moving the Spark Advance Lever inside the cab, all the way up and/or all the way down, the spark retard arm on the distributor should not make contact with the Upper Distributor Body on either side.

      The fix: For the 29-31 two tooth steering, loosen both steering column clamps. One is inside the cab and the other is under the hood. Rotate the steering column until the arm functions properly. Tighten the clamps.
      Inspect the Distributor Shaft.

      The Distributor Shaft should not rock back and forth. If it does rock, it is time to replace the bushings.
      Slight rotational play is ok.
      Setting Rotor/Distributor Contact Gap
      Put on parking brake, place gear shift lever in neutral position, and use the Hand Crank to rotate the rotor.

      Check the rotor at all four distributor contact points. The gap should be .025



      The fix: Bend the Rotor and/or file the contacts on the Distributor Housing.
      Setting Point Gap
      To adjust points proceed as follows:
      1. Lift off distributor cap, rotor, and body. Turn engine over slowly with hand crank until breaker arm rests on one of the lobes of the cam with the breaker points fully opened.
      2. Loosen lock screw and turn the contact screw until the gap is between .018 and .022”. A standard thickness gage is used to obtain this measurement. When correct adjustment is obtained, tighten the lock screw. After tightening the lock screw, again check the gap to make sure the adjustment was not altered when the lock screw was tightened.
      3. Replace distributor body, rotor and cap or proceed to ignition timing.
      Ignition Timing:
      1. Inspect the Distributor as stated above.
      2. Put on parking brake
      3. Place gear shift lever in neutral position
      4. Fully retard spark lever.
      5. If not previously done, remove the distributor cover and lift off rotor and distributor body.
      6. Check Point Gap. If necessary adjust them as previously described above.
      7. Screw out timing pin located in timing gear cover and insert opposite end of pin into opening.

      8. Find Top Dead Center. With the hand crank, turn the engine over slowly, at the same time pressing in firmly on the timing pin. When piston # 1 reaches the end of the stroke (top), the timing pin will slip into a small recess in the cam gear.

      Tip: If the engine had been running recently, the timing pin should drop into the recess when the rotor is about to line up with contact #1 on the distributor cap.
      Note: While hand cranking to find the timing mark mark, occasionally pause to relieve the compression pressure.

      Note: If the timing mark is missed it is two revolutions, with the hand crank to return to the previous point.

      Note: By removing Plug # 1 and shining a small flash light into the hole, it is possible to see the top of the piston when you are at Top Dead Center.

      Note: By removing all the plugs, the compression is eliminated and the engine is easier to hand crank.
      9.Remove the cap and rotor. Loosen cam locking screw until the cam can be turned. Note: A cam wrench can be purchased from one of the Model A venders, makes the job easier.

      10. Replace rotor and/or use the cam wrench to turn and line up the notch in the cam with the No1 contact point on distributor head.

      11. Remove rotor and/or wrench from cam and using your fingers slightly turn the cam in a counter clockwise direction, until the breaker points are fully opened.

      12.Slowly turn the cam back in a clockwise direction until the points just close.
      13. Lock the cam by securely tightening the cam locking screw. This method removes the backlash in the distributor shaft from affecting the timing.

      14.Turn on the ignition and with your fingers twist the cam counter clockwise. With the slightestmovement the points should spark. If it does not spark retime.

      Final check with the ignition on pull the spark advance lever down one or two notches and listen and/or have someone watch for a spark from the points. If the lever moves more then three notches retime.

      Replace timing pin and put away crank

      Oil the distributor and Apply Vaseline to the cam.

      15. Reassemble distributor housing, rotor, and cap
      Model A's are positive ground. The Model A frame acts as the positive ground wire from the battery


      Primary System 414.gif
      The Primary Circuit.
      The primary circuit is the low voltage circuit that controls the ignition system.
      • Battery - provides the power to run the system.
      • Ammeter - Used to measure the current flow.
      • Ignition Switch - allows the driver to turn the system on and off.
      • Points - a mechanical switch that acts as the triggering mechanism to break the circuit to collapse the magnetic field in the coil.
      • Condenser - provides a false ground and protects the points from burning out.
      • Primary Coil - produces the magnetic field which collapses and creates the high voltage in the secondary coil.
      • Wires - join all the components together.
      • Model A Frame - acts as the positive wire used for ground.
      The Secondary Circuit

      The Secondary Circuit is the high voltage side of the ignition system. The voltage is generated when the magnetic field collapses in the primary windings.
      • Secondary Coil -Creates a high voltage when enacted upon by the collapsing of a magnetic field in the primary coil.
      • .Coil Wire - a highly insulated wire, that takes the high voltage from the coil, to the distributor cap.
      • Distributor Cap - a plastic cap with an electrode to distribute the electricity to the rotor.
      • Rotor - spins around on the top of the distributor shaft, and distributes the spark to the right spark plug.
      • Plug Connectors- metal strip that takes the high voltage from the cap to the plugs.
      • Spark Plugs - Highly insulated electrode that forces electricity to arc across a gap in order to ignite a fuel air mixture in a combustion chamber of an engine.
      Primary and Secondary System

      The ignition switch allows the driver to turn the system on and off. Turning the key to the on position closes the circuit and allows current to flow. As current flows around the primary coil, a magnetic field is created. The strength of the magnetic field is determined by how long the points are closed.

      The points act as a mechanical switch that is controlled by the distributor's cam. When the points open, the circuit is broken; this instantly collapses the magnetic field and induces a high voltage into the secondary windings. The voltage is so intense that in its path to ground, it is able to ionize the air gap of the spark plug, thus igniting the fuel air mixture in the combustion chamber.
      How The Condenser Works

      The function of a condenser is to provide a false ground. When the points open and the magnetic field collapses in the coil. A high voltage is created in both the primary and secondary windings. The voltage in the secondary windings heads towards the spark plugs to ignite the fuel; while the new induced voltage in the Primary windings searches for ground. The voltage created by the collapsing of the magnetic field in the primary coil is strong enough to jump the gap between the points in the distributor as they open, but instead, the current is attracted to the condenser, where it is collected and stored to assist in the next cycle of creating a magnetic field in the Primary Coil.
      Note: At one time the condenser was considered the weak link in the system and failed often. Today's reproduction condensers do not fail like their predecessors and are quite reliable.
      Tom Wesenberg Tip:
      "Condensers are very easy and quick to change if you follow these steps exactly.
      1. Have the new condenser lying next to the distributor.
      2. From the passenger side, remove the ground screw FIRST.
      3. From the driver’s side remove the condenser terminal screw and be sure to keep light pressure on the screw while you slip out the old condenser and slip in the new one.
      4. Tighten the terminal screw, then go to the passenger side and tighten the ground screw.
      Always set the points to .020” first, then set the timing. Remember that the points setting can affect the timing, but the timing can’t affect the points setting. Be sure to have lube on the points rubbing block. I always carry a small piece of sandpaper in my billfold just in case I need to clean points, or check an engine number at a swap meet, etc. A points file is good to keep in your car’s tool kit and only costs about a dollar."
      How The Coil Works

      The coil itself does not care which way it is hooked up, it will be just as efficient either way. On the other hand the spark plugs do care. They prefer the center electrode to be negative and the end electrode to be positive. The reason is electrons like to jump from a cold surface to a hot surface and the center electrode of a spark plug is hotter than the end electrode. By correctly establishing the coil’s polarity the voltage required to jump the spark plug gap is 15 to 30 percent stronger which may or may not be evident on the performance of your ‘A’ depending on the condition of the ignition components. Oddly enough the large amount of voltage created by the coil is not affected, positively or negatively, by the mere 6 volts (or 12) of the battery. Therefore; positive ground or negative ground of the battery is not relevant.
      Tom Wesenberg Tip:
      "To check coil polarity hold a pencil lead in the spark path with the plug wire about a third of an inch away from the distributor terminal. You’ll see a FLARE on one side of the pencil lead and this flare should be on the spark plug side of the lead." Tom suggests to hold the pencil in the middle or even slide the pencil into a plastic tube to avoid an electrical shock.

      If the flare is on the plug wire side. Switch the two wires on the coil.
      Attached Files
      2 1930 Tudors

      Henry Ford said
      "It's all nuts and bolts"


      Mitch's Auto Service ctr

      Comment


      • Kevin in NJ
        Kevin in NJ commented
        Editing a comment
        Something that needs to be considered when commenting about oiling the dist. The Ford manual tells you to fill up the oil to the top of the oiler. This is important because this is how the upper bushing is oiled.

    • #5
      MAFCA Distributor Seminar

      https://www.mafca.com/downloads/Tech...eminar2012.pdf
      2 1930 Tudors

      Henry Ford said
      "It's all nuts and bolts"


      Mitch's Auto Service ctr

      Comment


      • #6
        That is the first time I have seen the previous postings on the distributor those are nothing short of fantastic. Thanks

        Comment

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