Piston Slap: Henry's Spark Plug Menorah?

Sajeev Mehta
by Sajeev Mehta
piston slap henry s spark plug menorah

TTAC’s own Ronnie Schreiber writes:


How many spark plugs do you think a Model T “trembler” ignition coil can fire simultaneously?

I’m foolishly trying to make a spark plug-based Chanukah menorah (candelabra), so I need to have as many as nine plugs sparking at the same time. I could use individual coils but those run about $100 each and I don’t want to spend a thousand bucks on this project.

Yes, I know the voltages are dangerous.

Sajeev responds:

I’m not surprised you asked me this, and let’s not dwell (sorry) on the imminent danger of an ignition system-based menorah.

Henry Ford’s possible objections notwithstanding, using Model T tremblers for a spark plug menorah is doable. But since the Model T needed one trembler for each plug, you could need 9 of them. While I can’t find the trembler’s specs, judging by the YouTube videos, they sure look powerful (and dangerous). Maybe one could power two plugs! But while they are cheaper than full retail on a modern coil, they ain’t cheap.

Unless you have used tremblers lying around, what’s stopping you from buying used coil-on-plug units? They are under $40 at my nearest junkyard, but I guess it won’t look as cool as nine big boxes mounted remotely from the menorah.

I’d probably just stick with candles.

What say you, Best and Brightest?

[Image: Ford]

Join the conversation
8 of 41 comments
  • PandaBear PandaBear on Feb 21, 2020

    At atmospheric pressure, you can probably daisy chain them together in a "waste spark" configuration and then just use a regular coil. The problem is more on how are you going to keep them all fired up at all time without burning out anything.

    • SPPPP SPPPP on Feb 21, 2020

      Daisy chain might work. But whatever you do, I think you might want to consider lampshades on each plug. I don't think unshielded arc light is a good idea for the eyes of your family.

  • ToolGuy ToolGuy on Feb 21, 2020

    Level I (safer than candles): Get a 10-light LED "chaser light" soldering kit; relocate 9 (or 8) of the LED's to the inoperative spark plug gap spaces. Enjoy the [silent and safe] "Knight Rider" effect. https://www.youtube.com/watch?v=WxE2xWZNfOc Level II: Obtain one (and only one) trembler coil. Obtain and assemble a "Velleman K8044: 10-Channel Light Effect Generator Kit" and link 9 (or 8) of the relay outputs to the spark plugs (each lead to each relay, common ground). Enjoy the "Knight Rider" effect but with sparks instead of lights. Since the plugs fire sequentially, the original question of 'how many can fire simultaneously' is moot, and the duty cycle on the single trembler coil will be as per original design intent.

    • See 2 previous
    • SPPPP SPPPP on Feb 21, 2020

      @ToolGuy I considered suggesting an electric motor spinning a V8 distributor, but then I thought about the Hz required for a pleasing visual effect (estimated 30 Hz*60sec/min = 1800 RPM) and decided that it might be loud and/or wear out quickly.

  • Why not tesla coils? “Anything worth doing, is worth doing right.”

  • Cprescott Cprescott on Feb 24, 2020

    Is this the first question asked by an official Schmuck?