| November/December 1972

  • Flywheels
    Courtesy of George F. Kempher, 110 7th Street, Emporium, Pennsylvania 15834.

  • Flywheels

35640 Avenue F, Yucaipa, California 92399.

I wish to add a few remarks to the excellent article in the Sept.-Oct. issue of GEM as submitted by Mr. Stambaugh, re Oil pull Tune-up. This is based upon my experience with my model M 20-35 fine old Rumely.

In this particular case (not Case), the water tank had long since become rusted away and discarded before I acquired the prize from the junkyard in Spokane, Washington. Also, since the running service which 1 expected from this engine was comparatively light, and the availability of distillate or kerosene was scarce, to say nothing of the higher price compared with gasoline, and since it was usual to start on gasoline anyway, I decided to operate on gasoline straight.

Of course, the first thing which thus became apparent was a very bad ping during ignition in the cylinders, with the original 35-degree running advance, with no water for cushioning. However, I did some experimenting and found that with leaded types of gasoline the engine would operate like any straight gasoline stationary or tractor if the spark was set for about ten degrees running advance. This put it in the category of the old 20-40 Case gas tractors and others of that vintage; that is, slow running engines. Now, as mentioned above, I would not expect to obtain the full power under such conditions, as compared with a good kerosene-water mixture which would result in an expansion much like a steam engine at short cutoff. But it does allow of easy convenient startup and handling, and at low cost. While Mr. Stambaugh did not call out the particular allowances to be employed between cold and hot valve clearance settings, it is presumed that the valve settings as given for cold might be rechecked after the engine had become well warmed up. This would prevent any hold-open and consequent burning of valves and loss of power.

Hornsby Ackroyd, No. 313 Crued oil vaporizing 16' diameter x 20' stroke. Has crosshead on piston rod. 7?' x 6' flywheels and 5' diameter crankshaft. Weight 7? tons. Paul is standing near this engine.

Again, speaking of the; reliability of starting one of these old timers in the coldest weather, do we readers recall that 'downdraft' carburetion .(mixing) was employed on these old timers long before the automobile industry fell wise to its advantages? This makes for easiest starting in cold weather because the mixing bowl is mounted directly on the cylinder head and thus any priming fuel is effectively dumped right into the cylinders with the intake air. I wonder if some of the automotive design engineers may have grown up with an old gas tractor? A minimum of intake manifold length thus offers least opportunity for fuel condensation in a cold engine. How well the old opposed motors would have responded had mixing bowls been mounted on each pair of cylinder heads rather than one bowl being connected with all cylinders by means of the exceedingly long intake manifolding!


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