Use of ethanol in older vehicles

Many states have jumped on the political bandwagon of pushing ethanol; which may be EXTREMELY DETRIMENTAL to older vehicles. Without going into the politics and/or cost both fiscal and to the environment of using ethanol, this article is designed to help at least keep the older engines running with ethanol fuel. Since we are carburetor specialists only, we will not get into the necessary modifications for fuel tanks, fuel pumps, fuel lines, etc., and leave this area for other specialists.

Ethanol has less energy than gasoline. Gasoline has 117600 BTU per gallon, ethanol 67000 BTU per gallon.

The common mixtures AT THIS TIME are E-10, E-15, and E-85. The number after the E is the approximate percentage of ethanol mixed with gasoline.

To determine the energy of a gallon of mixture, one may use the following equation:

BTU mixture = [(Percentage ethanol times 670) + (percentage gasoline times 1176)]

Thus:

E-10 BTU mixture = [(10 times 670) + (90 times 1176)]

E-15 BTU mixture = [(15 times 670) + (85 times 1176)]

E-85 BTU mixture = [(85 times 6700 + (15 times 1176)]

E-10 has 112540 BTU per gallon

E-15 has 110010 BTU per gallon

E-85 has 74590 BTU per gallon

For carburetors manufactured after about 1935 and a vehicle that is mainly driven at altitudes of sea level to 4000 feet, we suggest the following calibration changes to use ethanol fuel:

E-10 -lower float levels 1/32 from original specifications increase main metering circuits fuel flow by 5 percent.

E-15 - lower float levels 1/32 from specification, increase idle jet flow by 5 percent, increase main
metering circuits flow by 10 percent.

E-85 - nope, not going there at all, good luck to any that try it!

Additionally:

Accelerator pumps with neopreme skirts should be changed to those having leather skirts.

Foam floats should be changed to brass.

Carburetors with vacuum metering systems may need a recalibrated vacuum spring.

Failure to make these changes will cause the engine to run lean. A lean running engine will run hotter than normal, and this can cause premature failure of valves, warpage or cracking of cylinder heads, exhaust manifolds, etc.

For carburetors manufactured before about 1935:

IT MAY NOT BE POSSIBLE TO ECONOMICALLY RECALIBRATE THE CARBURETOR!

The key is the style of carburetor. The airvalve carburetors such as the Schebler model S (Auburn, Cord, Duesenberg, etc.) or the Detroit Lubricators used on 1928 and earlier Packards, and others, use a tensioned spring to control the mixture. The only way to adjust is to hand-wind springs of a different tension using the method of trial and error. It is often much easier to simply replace the carburetor with a more conventional unit that may be adjusted, especially if one is subjected to E-15. If one has a more conventional carburetor (no air valve) then the suggestions for post-1935 carburetors may be followed.