by loucrane » Tue May 25, 2010 4:49 pm
Surprised that the instructions mentioned "leaded" gasoline! So, soak it in the available unleaded...
I seem to remember that "white" (UN-leaded) gasoline was recommended for spark engine fuel. AMOCO had a lead-free gasoline, if I recall. "White" gas was available from other sources than gas stations, and for other uses. Not in the recent 50 years or so, however...
Never flew spark in its day, but have read a lot about it ever since. I have used glow fuels and Coleman camp stove based fuel. Glow fuels with 5% or so nitro and 25% - or a bit more - castor oil are very much less critical to needle and spark settings...
Unleaded pump gas - lowest octane you can find - just has to be better than the Coleman. It may mix with castor oil, but an SAE 60 or 70 single weight petroleum-based oil is more certain. Try Harley-D shops for a good 60 weight, or a specialty auto-, kart- or boat-racing shop might be able to get you some SAE 70, like Kendall NITRO 70. Gear lubes are not suitable
Glow fuels are based on methanol. There were problems when some spark engines were tried on glow plugs and glow fuel - the plastic tanks, that many sparkers came with, dissolved! I presume you understand that fuel tubing for glow fuels may not work with gasoline. (Diesel fuel, based on kerosene, makes silicone fuel line swell to more than double its diameter. Gasoline may do the same...)
Luck!