... schematic of a typical conventional breaker-point ignition system

POINTS IGNITION DISTRIBUTOR : SLANT 6 (CAST ALLOY)

Points Ignition Lovers: Are They Misinformed..

Cal-Van Tools 693 Ignition Point File

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  • Electronic Ignition systems are not as complicated as they may first appear. In fact, they differ only slightly from conventional point ignition systems. Like conventional ignition systems, electronic systems have two circuits: a primary circuit and a secondary circuit. The entire secondary circuit is the same as in a conventional ignition system. In addition, the section of the primary circuit from the battery to the battery terminal at the coil is the same as in a conventional ignition system.

    Electronic Ignition systems are not as complicated as they may first appear. In fact, they differ only slightly from conventional point ignition systems. Like conventional ignition systems, electronic systems have two circuits: a primary circuit and a secondary circuit. The entire secondary circuit is the same as in a conventional ignition system. In addition, the section of the primary circuit from the battery to the battery terminal at the coil is the same as in a conventional ignition system.

  • For those of you too young to remember when points ignitions ruled the roads, just imagine broken-down cars with their hoods up every few hundred yards on the highway. Imagine parking lots echoing with the sound of engines farting, sputtering, and ultimately failing to start, and the associated screamfests among the stressed-out victims. Imagine getting 4 MPG a few thousand miles after your last tuneup; in fact, imagine having to do tuneups every few months. For all these nightmares and more, what was the culprit damn near every time? Ignition points!
    We're talking about a simple little device here, basically just a spring-loaded switch inside the distributor that opens and closes to fire the spark plugs, via a little cam on the distributor shaft. It's a low-grade pain in the ass to get a new set adjusted right, involving feeler gauges and a bit of back pain, but anyone can learn how to install and adjust ignition points… and therein lies the deadly allure of the cursed things: when a car with a points ignition system is running like crap, most of the time you know right where to look for the problem, and you can fix it for cheap with a couple of hand tools and 15 minutes. You are a hero! A problem solver!

    The spark plug fires when the points open. Since the point of ignition timing is to have the spark plug firing at the correct time/point in the cycle, figuring out when the points are supposed to open is important. Most of the time, the manual will give a number or range of numbers in either mm before TDC (BTDC) or degrees BTDC for where the piston should be when the spark plug fires.



    1. Point gap on each set of points must be set at 0.3~0.4 mm (0.012"~0.016"). Constant electrical arcs across the points cause some metal to burn away, changing point gap. Clean and regap the points every 2,000 miles. Check timing after regapping.
    2. To clean the points, run a point file between the points until the gray deposits and pits have been removed. Spray the points with ignition point cleaner or lacquer thinner, then snap the points shut on a white business card (or paper of hard texture) and repeatedly pull the card through until no more carbon or metal particles come off with the card. (The card may be dipped in lacquer thinner or other cleaner to facilitate this procedure).
    3. To gap the points, first rotate the engine until the ignition cam opens the points to their widest position. Slip a 0.4mm (0.016") feeler gauge into the gap. It must be a tight slip fit. If an adjustment is necessary, loosen the point lock screw (1 or 2) as shown in the accompanying drawing, insert a screwdriver into the adjustment slots (3 or 4), and open or close the points until the feeler gauge indicates the correct gap. Retighten the lock screw and recheck the gap.
    4. Next, rotate the camshaft until the second set of points opens to its widest point. Then perform the same steps as described in the previous paragraph.
    Note:
    Add a few drops of light-weight oil into the felt rubbing pad after each points adjustment to lubricate the point cam surface. Do not overoil.


  • Rotax 377, 447, 503 aircraft engine tachometer and rectifier wiring diagram.


    Rotax 377, 447, and 503 Bosch points ignition wiring diagram

    These early Breaker-Point distributors suffered from Points-Bounce. That is the harder the points slammed closed, the more they tended to bounce open again like a rubber ball bouncing on concrete. When the points bounced they caused the Coil to spark prematurely causing one of the plugs to spark at the wrong time. The bounce also prevented the Coil from generating enough energy for the next spark. Points-Bounce affected the note of the engine. Distributors that are Magnetically or Light-Source triggered cause each spark to occur at exactly the right time every time. As a result the engine note is one of precise firing of each cylinder as opposed to a general sort of "rasp" that the early engines fitted with Breaker-Point ignition made.

Bosch ignition, Bosch points ignition wiring diagrams.

I like points ignition systems. If they start to fail it always seems you can fiddle with them and limp home. If something needed replacing, you didn't have to get a loan from the bank to buy the part. Too bad they are fading away like old soldiers.