Tuesday, November 24, 2020

My Little Engine is Pointless

I should make that, "despite my best efforts, my engine is pointless...um... pointsless?"  The engine is designed for an old-fashioned points, ignition coil and capacitor (condenser, if you must) ignition.  I decided to upgrade it to a capacitive discharge ignition (CDI) for model engines, from a guy who sells to the hobby engine makers.  At that point I had a choice between using a hall effect sensor or the points and decided to stay with points. 

The plans say to use points from, "1969 DODGE CHARGER, 383, 4BL, W/SINGLE POINT DIST" but the only place where that matters is in the mounting dimensions. I could have adjusted the piece of metal that the points mount to, if I had understood that back when I was getting started (this is one of the first pieces I made for the engine).  Let's say I had a set of points from some really old car I used to have; I could have redesigned the mounting support and used those.  I eventually searched for points on AutoZone and Advance Auto Parts; the two national chains are within a block or two of each other and a couple of miles from home. I had to pay for the points at AutoZone on Saturday and have them delivered to my local store from their regional warehouse in Orlando.  I got them this afternoon and had them installed quickly, once I found the two screws I needed.

Something's missing.  These are actually the wrong points in AutoZone's cross reference.  You can see a sheet metal spring hanging off to the lower right around the black SHCS, and to the lower left of that screw is the moving contact on its plastic mount.  The plans for the engine show a bent up piece of metal on the bottom of the arm between the two mounting screws (flat blade/slot screws shown), and a stud with hardware on it (circled in red) between the screws connecting the points to the capacitor. 

A little more research took me to their competitor, Advance Auto Parts, and they have the points I need.  Tomorrow I'll call or drop by to see if they stock them or I have to order from Orlando again. 

Until I get the points, I have more stuff to do.  I need to cut a little gasket material to go between the cylinder and cylinder head.  In the last couple of days, I put together a little fuel tank holder to keep the tank in the right relationship to the carburetor input.  Hopefully.

That's two U shaped aluminum uprights on a 3/8" thick aluminum plate.  The plate needs some finishing work done on it to make it look nicer.  Actually, everything could use some "prettying up," it's just too late for most of the engine.  I've seen people run these electronic ignitions spread across their workbench, and I need to take a look at making a little box for that.  I will assume attention should be paid to whether it's metal and all ground or maybe made of wood.

I have no idea how long it will take to get this running.  It took me several tries to get my flame eater to run OK, and I'm sure there's a lot here I'll need to do.  OTOH, I've bought or made everything I think I need - and I don't think another problem like the wrong points is possible.  I sure would like to have this running soon, though. 


  1. No NAPA store close by?

    What are you using for a coil? It might need a "Ballast" (current limiting) resistor.

  2. The coils Ford used on their TFI systems are fairly compact and rectangular. A simple bracket to mount them with two screws. Super simple to wire up and they will definitely light you up if you grab a leaky plug wire. There are tons of aftermarket copies available.

    1. I'm gonna file this away, and if I can't make the electronic ignition work, I'll do this. If you make more than one engine model, you need to either have a common ignition you can move between them or put one on every engine. Most guys go with one in a box that they can swap between engines.

      Maybe the hall effect switch and magnet might have been a good way to go, but points were cheaper. The first car I owned was a '72 Pinto, which had plain old points, coil and cap (of course). I tend to keep cars a long time, so the next one in '82 had some sort of electronic ignition - never needed to gap the plugs.

  3. I would have chosen air cooled VW points.

  4. Off point, but have you considered a light interrupter to trigger an electronic spark system?

    1. To be honest, I've given very little thought to making or improving the ignition system. Same reason I bought an RC model carburetor and fuel tank instead of soldering one together from brass tubing and making it very pretty. I've always thought my challenges would be in getting this thing running, and that means things like the piston fitting the cylinder properly, the valves sealing, opening and re-seating properly and a host of purely mechanical aspects. Most of the parts in this engine are the first time I've made anything like them.

      This is my first attempt at an internal combustion engine made from bar stock; just bars, rods, plates or other pieces from the factories that sell them.

  5. Once you get it running, SiG, you need to get a mini super-charger like this guy made. :-)


    On a more serious note: I wonder if you could use a Pertronix module and employ a flying magnet set up for the ignition? No friction and no gap to set. They are stand alone as well, less a coil - of course.
    Some custom engine tuners use the current GM "LT" engine coils for individual coil per cylinder, engine management. They also have a more easily mounted framework than the Ford "COP".

    Whitehall, NY

    1. That guy did a video on the little 5-axis CNC system he bought and I've been mulling over how to make one. I have a four axis setup but rarely use it because the CAM programs that I can get don't use the rotary axis, or only allow three axes in any program.