I have been running this engine in on Davis fuel and now it is turning a MAS 9X4 13,200 with reliable idle of 3200. So far that's really more than I would have expected. The factory recommends 45% ether which I imagine is higher than Davis. It seems to need more pressure than it gets from muffler tap. Now should I change fuel to the 45%E ? Is it OK to tap the center of the plastic backcover for a 90 deg. fitting?
Thanks , Ralph

Ralph,


This cute, little Diesel is making a very respectable 0.33 HP at this relatively low RPM.

MVVS uses a steel sleeve, replacing the true ABC setup for it.


To honor the warranty, you should use the manufacturer's recommended fuel.
In reality, as long as you keep the Castor oil content at the recommended level, no damage should occur.
Ether is somewhat less energetic than kerosene at 15,000 btu/lb, compared with about 19,000, so replacing some of the ether with kerosene could give you a bit more power.

Ether is, however, the more volatile, compression sensitive ingredient of the fuel, and MVVS' 45% recommendation is at least in part, to make the engine easier to start and to make it idle more reliably.

Using crankcase pressure to pressurize the fuel tank is not recommended in an R/C engine.

The carburettor will be getting a less consistent pressure curve, when compared with muffler pressure. ...And a Diesel should have very good suction for fuel, making even muffler pressure unneeded.


I would not recommend drilling the back-plate.

See if one of the back-plate top bolt holes extends into the crankcase and use a pressure fitting with the same thread, but it is not recommended anyway.