Water-Inducted Wonder

Two-Cycle/ Hot Bulb, Kerosene Fueled Water Induction - The Mietz a Weiss Oil Engine Had it AH

| February/March 2003

  • Mietz & Weiss

  • Mietz & Weiss
    Back side of the Mietz & Weiss, crankshaft oilers in full view.
  • Mietz & Weiss

  • Mietz & Weiss

  • Mietz & Weiss
  • Mietz & Weiss
  • Mietz & Weiss
  • Mietz & Weiss

Jeff Conner's 1-1/2 HP Mietz & Weiss, serial number 1988. Jeff's engine is an early example, built before 1905 when Mietz & Weiss changed from a manually controlled water induction system to an automatic system using steam. Mietz & Weiss started building engines in 1894. Remarkably, this engine has its original muffler

Seven years ago, after finding a nice 6 HP Witte diesel and getting it running, I got interested in predecessors of true compression-ignition engines. I knew about Thermoils, and a few other early examples, but as I learned more I set my sights on finding an early hot bulb oil engine - and it had to be small.

Coincidentally, I made the acquaintance of engine collector Don Clickner, Troy, N.Y., after a fellow employee introduced us. Don and I discussed our mutual interest in old engines, and I asked him if he had ever seen any small hot bulb oil engines. 'Sure,' he said, 'how about a 1 -1/2 HP Mietz & Weiss oil engine?'

As it turned out, Don had a friend who rescued a Mietz & Weiss - this Mietz & Weiss - from an old farmhouse before the house (and the engine) was cleared away as part of a reservoir project. Don's friend had passed away, and Don had been storing the engine for the past 15 years as a favor to his friend's family. After telling me about the Mietz & Weiss, Don contacted the family to see if they would consider selling it to me. To my great fortune, they agreed, and that is how I came to be the custodian of this interesting little engine.

Mietz & Weiss Engines

Mietz & Weiss oil engines are two-cycle, crankcase-scavenged, hot-bulb ignition kerosene engines. They use a dry, hot-bulb head, the hot bulb initially heated with a torch, operating at a dull red heat to ignite fuel injected into the cylinder. 'Squirted,' might be a better word than 'injected,' as the fuel system operates at very low pressure. A solid stream of fuel 'squirted' into the cylinder hits a small lip projecting from the hot bulb cavity at the front of the cylinder. The fuel splatters on impact and is then swept into the hot bulb cavity by the incoming combustion air, where it ignites from the surface temperature of the bulb. The fuel is squirted into the cylinder just after the air intake port is closed by the piston -there is no precise fuel timing.


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