Jim Smart
May 1, 2009

If you've been walking the planet for any time at all, you're familiar with the energy challenges we've been facing since the mid-'70s. Prior to 1974, gasoline was plentiful and cheap as we pumped it into our Mustangs at 23 cents per gallon. Some of you remember gas wars. Service stations priced gasoline so low that they nearly paid us to pump it. When I came of age, you could cruise all night on a $3 fill-up.

All that cheap and plentiful gasoline went away in the winter of 1973-'74, when the Arab Oil Embargo doubled fuel prices overnight. Many gas stations ran out. We faced long lines and some states initiated odd/even license plate days where you were only permitted to buy gas on your day. We didn't see the energy crisis coming, but when it arrived, it was sobering.

For 35 years, we've had it drummed into our heads to be less dependent on foreign oil, yet we're still in denial as we continue to pump petroleum into our automobiles. To reduce consumption of crude and improve exhaust emissions, oil companies have whipped up all kinds of different gasoline cocktails through the years. One such additive is ethanol; you've no doubt seen the signs on the pumps advising that the fuel contains 10 percent ethanol.

So aside from obviously using less petroleum, why mix ethanol with gasoline? Ethanol, also called ethyl alcohol or grain alcohol, adds oxygen to reduce air pollution. Before ethanol, the oil companies oxygenated fuel with MTBE (methyl tertiary-butyl ether), a chemical compound that comes from a reaction between methanol and isobutylene. It is quite volatile with a high evaporation rate. When it was learned MTBE was hazardous to ground water supplies, the EPA mandated alternatives such as ethanol.

Gasoline isn't as user friendly as it once was because it now has additives designed to clean up emissions and help sagging octane. These additives, including ethanol, are especially hard on vintage Mustangs with their rubber fuel hoses, carburetor float needle valves, die-cast carburetor bodies, galvanized fuel tanks and lines, and related components. Some owners have reported problems with phenolic carburetor floats.

Because ethanol accelerates the deterioration of vintage fuel system components, you must take care of regular preventative maintenance more often. All fuel system rubber parts should be replaced annually and inspected frequently. Because ethanol tends to be hard on die-cast carburetor bodies, this also calls for close inspection because ethanol and zinc don't get along well. Although ethanol probably won't harm your carburetor's metal parts, there's always some element of risk (depending on your carburetor's metallurgy).

In the good old days of high-octane leaded fuel, it was easy to overlook fuel hoses, float needle valves, carburetor rubber parts, fuel pump diaphragms, and carburetor gaskets. These items deteriorated slowly, requiring only periodic maintenance. Neglect them today and it can bite you with fuel leakage and the potential for a fire. Fuel-related fires have become a problem with older fuel systems because owners are not staying on top of important maintenance issues.

The jury remains out on the adverse effects of pumping E10 into our Mustangs. E10 is 90-percent gasoline and 10-percent ethanol. And that's what you can expect at most gas pumps today. E85, which is 85-percent ethanol and 15-percent gasoline, should never be used in a classic Mustang.

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One known ethanol issue is water retention. Like brake fluid, ethanol likes to retain more water then gasoline. Because ethanol tends to be hard on rubber and cork components, you can wind up with leaks and bits of rubber in the fuel system, which can cause a sticking float and plugged passages. This is why visual inspection of fuel bowls is important from time to time.

Available heat energy from ethanol is what makes it a good octane enhancer. We can bump compression a little higher and achieve more power without detonating an engine to death when we run ethanol. That's the good news. The bad news is the detrimental side effects of ethanol in gasoline when used in older cars.

Regular Preventative Maintenance for Vintage Carburetors
Because there isn't a carburetor kit designed for today's harsher fuels, you must inspect and service your fuel system more often than you used to. Here's what you need to do every six months.

  • Inspect the carburetor externally for fuel leaks around the accelerator pump and power valve.
  • Look for leakage around the throttle shaft.
  • Remove the air horn and inspect both float and needle valve.
  • Examine carburetor internals for evidence of leakage from a sticking float.
  • Inspect throttle plates for evidence of fuel dribbling.
  • Work the throttle and check accelerator pump shot quality.