Car started to sputter the other day at full acceleration. After checking the obvious. Wires, vacuum and filling up with fresh fuel. Still there. Hit and miss. Checked the tank and filters. Still couldn’t figure it out. Took the carburetor off and found this. There is pitting in the bottom of the bowls. Some big enough to feel with a fingernail. Looks as though the metal is being eaten by the gas, or whatever additives are in it. First time I am seeing this. Is there anything I can do to stop the pitting and corrosion, or do I need to replace the carburetor.? Thanks.

 

What percentage ethanol is in the gasoline you are using?

 

91 octane 10% ethanol. best i can find. My concern is, that now that the coating is gone in those spots the metal will continue to corrode.

 

Hi Gold Dragon, welcome to the fun residuals of corn gas in our old equipment. When I had the Holly carbs rebuilt on our tri-power, I had to have some parts replaced due to pitting from corn gas. The 'shelf life' of corn gas is much shorter than pure gasoline, it attracts moisture, is tough on rubber lines, etc. I would recommend:

• Checking your gas tank to ensure their is no bad corrosion there. Include checking the pickup sock and change it if needed.
• Replace the fuel filter.
• You may or may not need to have your carb cleaned up/rebuilt. If so and it's a Qjet, my money is on Lars.
• Switch to non-corn gas. I run a blend of 110 leaded/no corn with 92 unleaded/no corn in our '68 L71. It likes it.
• Check out this site to help you find pure gas: https://www.pure-gas.org/

It'll be okay, but it's just one of those things that our older cars don't like. I also run non-corn gas in our small equipment. Best, Paul

 

I would rebuild with Lars.

 

Golden Dragon.

That pitting of the brass float is from storage. It's not from actually running fresh Ethanol daily but rather from sitting for weeks or months.
Ethanol attracts moisture. And that is the root of the cause. Estimated shelf life is around 60 days before things go sour.
There is no need to use expensive Ethanol Free on a daily basis. Save your money. However, that gas is recommended as the last full tank of the season, before storage.

I would just buy a new float, clean out the fuel bowl, maybe swap-out the needle & seat.

My carb sits for 6 months. But I add Lucas Anti Ethanol Safeguard to the tank in the fall. No issues.

Look on Ebay for a new float matching your carb model number. Summit Racing sells carb parts on Ebay under an undisclosed name.
That way, you may get EBays free shpg.

 

My guess is that you bought gas at a 'questionable' gas station. Some of these outfits put regular fuel in all of their tanks...they just charge more for the mid and high octane pumps. The computers on modern cars will allow them to run OK if the fuel is a lower grade. Pre-computer cars....not so much. It could also be that a gypo fuel supplier put low grade gas in the hi-test tank at the station or that someone made an honest mistake. Call the station where you filled up last and ask them if there have been other complaints like yours.
You can put octane boosters in your fuel to see if that fixes the problem you are now having.

 

Why would octane of gasoline cause deterioration of the brass float bowl?

 

It doesn't. The float corrosion issue has nothing to do with the octane.

Ethanol by itself is 109 octane. How much, or what percentage of that is blended in with everyday gas determines the rating at the pump.

Ethanol seems new to us in the last couple decades or so. It's nothing new. Been around since 1908.
In fact, the Ford Model "T" ran on Ethanol.

 

What brand of gasoline do you use? Here in Iowa, I run BP 91 octane. It has no ethanol in it.

 

My go to brand, when i can find it is Shell. They have only one in this little town and it's out of the way for me. The rest of the stations here are convenience stores that all pull from the same local petroleum company.

 

A polymer Nitro-fil float will prevent the ethanol from damaging [non-ferrous metal] brass float in your carb. The worst thing about ethanol in fuel is that it can separate when stored for long periods and do some real damage. If vehicle is run frequently, ethanol is not as much of a problem...but it still presents issues (ie, lower boiling point).

 

Had me curious, so I looked it up.

Boiling points:
Gasoline 95* F
Ethanol 173* F

Vapor lock would happen sooner w/gas.

 

please I am tired of reading a million articles about using 10% ethanol gas !! There is absolutely nothing wrong with using ethanol gas Simple solution DRIVE THE CAR !!!! Most of all the people that have problems with ethanol gas are the people who put their cars to sleep for long periods of time or for the winter (6 months ) and wonder why come spring they have all sorts of of problems.. People are like sheep they will follow and listen to what others say without absolutely no proof of theory.. If you live in an area that uses salt on the roads than yes I would wait for a good rain to wash it away. However if the roads are clear fire her up and drive the car ..heck have spoken to some corvette owners and they said they will not drive there car because it’s too cold out ..😳😳 .. you guys treat these cars like they were never abused and driven. I Been running 10 % ethanol for over 35yrs in all my classic cars and never ever had one problem with rubber corrosion or anything else related to ethanol gas because I don’t let them sit idle for months and look at them in the garage. The gas is never idle for long periods of time . I can guarantee you come spring you will see a 100 posts about carburetor problems , wheel cylinder's leaking, gaskets leaking blah blah blah . DRIVE YOUR CARS often , even if you just start in the garage for 20 minutes it better than looking at it with a cup of coffee !!!!!! Your car will thank you

 

In Nebraska once the salt, brine & sand hit the streets my Vette is parked because that good rain ain't happening until April.
Mine has sat out every Winter starting with '76-'77, sometimes up to 6 months. No ethanol, no problem. And my factory lacquer appreciates the rest....

 

Yup. What you said, spot on. Ethanol is one of those pegs people hang their hat on like octane that is often misunderstood. My over the winter choice is Seafoam and I make a point not to let it hang around beyond 6 months. Zero issues and I mean zero and that includes generators and snow throwers that sit down in an unheated shed. It's just something else to consider in the maintenance schedule that I make a point to follow.

I had a couple of company provided service trucks over the years that I tried to run that corn liquor E85 in and I stopped. Not because it was causing problems but because I got half the mileage and had half the range and it just wasn't cutting it.

 

This would be an excellent question to bring to your local Chevrolet dealer's attention, as they are the experts with GM vehicles. If you need help connecting with a facility near you, feel free to email us at socialmedia@gm.com anytime.

 

They are experts and have parts for vehicles that are 43 to 57 years old? Really?

 

Re. post #13.... Mel,

According to the website I researched,

"The boiling point of regular gasoline is typically within a range, with the initial boiling point around 122°F to 158°F, while a 10% ethanol fuel mixture (E10) will have a slightly lower boiling point due to the presence of ethanol, which boils at a lower temperature than most gasoline components."

If I recall correctly, the difference is about -9*F. The 'base' gasoline used will have a specific boiling point, depending on additives, etc. Adding 10% ethanol to that same fuel will reduce the boiling point of the mixture.

 

No offense meant at all, but it may not be quite that simple. All gasolines are a blend of different additives, and have different boiling points. I found articles (and they're on the internet, so they must be true ) that indicate that E10 has a lower boiling point than 'pure' gasoline with the same additives without the 10% ethanol.

For example: gasoline generally has a higher boiling point than E10 (a gasoline blend with 10% ethanol) because ethanol, the main component added to create E10, has a significantly lower boiling point than gasoline itself; meaning E10 will boil at a lower temperature than pure gasoline.

I don't claim to be an expert on this by any means, but the comment caused me to google some additional questions.