10% alcohol in Gas - what maintenence for older car ?

The mixture screws only adjust the mixture at idle. At wider throttle openings, the idle air bleed screws are fairly insignificant in the grand scheme of things, and the mixture is determined by the sizes of the jets and metering rods. So if you're running a stock carburetor on a 30 year old car, it likely is not running as well as it used to, even if everything is in top condition and adjusted to spec.

nate

And don't forget that the new "gasoline" will have a very short shelf-life because the alcohol acts as an oxygenate and not only attacks everything in the fuel system, but the gasoline itself. Look forward to lawnmowers that need their fuel system purged and rebuilt every spring, snow blowers that need the same every winter, and cars that continually have plastic and aluminum fuel components fail for no apparent reason.

Thank your precious congressmen and politicians for caving into the huge ethanol lobby.... by sending them all your fuel system repair receipts.

Have you ever actually worked on a carburetor? That "little mixture screw" doesn't do ANYTHING except at idle. Do you drive your car with the throttle closed all the time? Didn't think so.

Sorry, I am used to airplanes, which have indeed a mixture control as well as an idle setpoint. So you're telling me that I'd need to drill out the jets (or install smaller ones) to change the mixture? What do people in Denver do?

--scott

It doesn't attack the gasoline... And in a system designed for its use, it doesnt unduly attack anything else.

All the major carburetor makers used to provide a range of jets, enrichment valves (aka power valves) and/or metering rods to adjust the mixture at idle, WOT, etc. Carter (now Edelbrock) and Holley still do for their performance 4-bbl carbs. Carter carbs are probably the easiest to do a minor mixture change on because you can pop off two small covers (on 4-bbl models) and change to a thinner metering rod (to enrich) or thicker (to lean). The problem is that you may not have the right jet/rod combo, so you might have to open the carb and change the jet to get the right setup. Holleys require opening the float bowls to change jets, but its fairly simple- although messy. Older 2-bbl carbs and all of the "smog era" carbs are much harder to get jets and other parts for these days.

Oh but it does. All "oxygenates" (alcohol, methanol, MTBE) tend to facilitate the oxidation of gasoline during storage, turning it into something about halfway between varnish and paint thinner that will thoroughly muck up a fuel system. It used to be that if you stored fuel in a sealed can, it would last indefinitely because the small amount of oxygen in the air within the can couldn't do much to it. Now it carries its own self-destructive oxygen with it...

That's the point- we're talking about systems NOT designed for its use.

Wow, Just had a tech class covering this (in part) The case study was a 2004 Ford Escape (I believe-resource is on my toolbox at work) Customer complained of running poorly at first and poor gas mileage, now it runs OK but mileage still poor. Was at the dealer twice they say everything's ok. Short term and long term fuel trim looks good on a standard scanner (about

11%), but on a Ford NGT scanner the Rear fuel trim assed another 11 percent to the equation. As the car is adding gas by the positive fuel trim readings, that means the car sees a lean condition. Filter and pump test good, so the shop runs a alcohol test on the fuel. 20%! California says no more than 10% Alcohol is best used in higher combustion engines and I believe he said takes twice as much to get the same bang per gallon as gas? The only car that can currently run on either gas or any mixture is a Saab with a turbo. It has a sensor that reads the mixture and adjust the turbo to run for whatever it sees. 100% gas about 140 HP,- 100% Methanol about 180HP. The interesting thing to see is that based upon the rate each fuel (or combo of) burns at there is NO MPG increase on this car from one fuel to another.

Will be interesting to see the long term of a state mandating 20%

Cite reputable sources, and I will take it into consideration. Most gum formation comes from catalyzed oxidation of unsaturates in the gasoline stock. That oxygen does not come from oxidates, but from the air. (Oxyen in alcohols, ethers, etc is not available to enter into reaction unless strong catalysis and heat are present.)

Typically, metals like copper or other heavy metals in trace concentrations can catalyze these reactions.

There ARE some issues with alcohols, but until you show concrete references to the contrary, I do not consider oxidative polymerization to be directly related to their use.

Actually, Esso is all I've EVER used since Imperial Oil bought Texaco. Other brands only get used in an emergency. (Those gas cards do work to retain brand loyalty, don't they?)

Well, I'll be the first to agree that correlation doesn't imply causation, but there is a HUGE reported correlation between short shelf-life and adulterated (excuse me, "oxygenated") gasoline. I've had old fuel (leaded, no less) sit in a stored car for 5+ years, crank right up and run just fine. Modern oxygenated gasoline will barely make it a year, if that. As I said before, there's only a limited supply of air in a reasonably sealed storage can or gasoline tank with controlled pressure/vacuum relief venting, so unless the fuel is carrying the oxygen itself, where's it going to come from?

Hey, lookit there. Baron von Credibility is back to show us all how much he knows.

e.

You introduce air each time you fill the tank. The gasoline in the storage tanks at the service station have some small traces of air in them

For a polymerization reaction to occur, you only need traces of the oxidizer. Parts per million levels are enough. And air contains about 210,000 parts per million oxygen.

I think you are observing the phenomenon correctly, but the reason for what you are observing may be a little more complicated.

The gasoline feedstock for oxygenated fuel should normally be different from unoxygenated fuel. This could be one issue. If alcohol bearing fuels allow more water entrainment, this can lead to the formation of emulsions, and in some cases may even allow microbiological activity. (You remember the old wet kerosene 'sour' smell? Bacteria, more accurately fungi, can cause this.) Also, water can carry the metallic catalysts (like copper traces) easier than gasoline can do it.

Often a shelf life of no more than 6 months is recommended for gasoline of any type. If kept clean and sterile and dry and cool and contained, it should last a lot longer than that, but in the real world, things tend to turn to crap in a hurry.

You probably meant high compression engines. Alcohol does not have the specific energy content that pure hydrocarbon fuels do, so they could not be expected to give the same performance in terms of economy per unit volume.

Ford representative has said that future Ford vehicles will be totally cross compatible between gasoline and alcohol.

There is a guy (Gunnerman) who has been touting burning mixtures of water and gasolinefor greatly increased economy and decreased emissions. ¨ Apparently he got enough interest in his claims to get some state agencies to back some of his studies.

There may be something of value in his claims. In Venezuela, Oremulsion technology was used to convert tarlike crudes to pumpable water emulsions so that it could be produced and sent to market.

Unfortunately, it was essentially impossible to separate the water from this ¨ crude, and it had to be sold a low grade marine fuel. As I remember the case, they sprayed the water laden fuel directly into the fireboxes and got about the same economy as if they had been spraying pure fuel oil.

Bottom line...I dont think alcohol is a good long term answer. If we should run out of affordable petroleum, we are in deep caca. I suspect that a diesel like fuel derived from tall oils or oil seeds might be the best renewable source of fuel, unless we make some significant breakthroughs in other areas.

In case anyone is interested in the Gunnerman saga, the above link should take you to some quick reads.

Not an issue. We're talking about a STORED tank full of fuel. Not opened for years. Yes, the air that's IN there can oxidize fuel, but its a limited amount (remember it takes 14x as much air as fuel to fully oxidize it).

I've never heard that. Why should it be different? Any documentation?

You may well be right about the mechanism- I'm an engineer, not a chemist (dammit, Jim!) but the key point is that alcohol adulterants contribute to the premature breakdown of gasoline in a significant way.

And in a lot bigger hurry when the gasoline is crapped up with oxygenates to start with.

I'm sceptical of this claim. My understanding is that the oxygenate (ethanol, MTBE, ETBE, TAME...) is added to the gasoline very close to the retail distribution level, *not* during manufacture. Certainly this is how it was done in the Denver-metro area right from the start in 1988. The reasons for this, as I understand it, are that oxygenated fuel has a much shorter shelf life than non-oxygenated fuel, different regions require/permit/prohibit different types and amounts of oxygenate, and gasoline with alcohol in it tends to accumulate contaminants (water, dirt) from each vessel and transport pipe it encounters at a greater rate than gasoline without alcohol.

The study at

states "Both the non-oxygenated and oxygenated test fuels used in the study utilized the same base stock. These fuels were refined locally and considered typical of this refinery based on the base stock common to both fuels. The oxygenated fuel selected was a 10% ethanol blend because ethanol has been used in 95% of the fuel distributed for the required oxygenated fuel program during the past several winters in Denver."

That's one of the key points. Another one: Significantly increased formaldehyde (+19%) and acetaldehyde (+160%) emissions:

And here's one that makes especially good reading:

Generally, mfgrs. set up carbs for sea level by default, and for high altitude locations they would provide dealers with high altitude jet kits to retrofit into the carburetors (or they could be ordered that way from the factory, if it was known that the vehicle would be operated at high altitudes.) I guess if you went from LA to Denver you would have had to stop somewhere along the way and have your carb rejetted.

nate

For holleys there are aftermarket blocks that take Weber parts and make tuning much easier. Q-Jets use metering rods. Switch to a more tuneable carb and you will be happier, or convert to MegaSquirt EFI which you can program with an old DOS laptop.