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Discussion Starter #1
Anyone have this problem? I have reddish brown crystals in the float bowls on my 4100 carb. The car has been sitting, but only for three weeks or so without starting. Last time I started it, the carb flooded and gas trickled out the vent pipe. I tapped the side of carb with a screwdriver handle and it stopped flooding. So the float was stuck with these crystals. I took it apart and found these crystals In the bowl in front. When I touch them they turn to powder. Some say it is the fuel, but? I only use Sunoco 93 unleaded so far. No additives in fuel. Any thoughts???
 

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Discussion Starter #2
Forgot to mention, new tank, new lines, new fuel pump, rebuilt carb
 

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don't know about the deposits, but the tail of the acc. pump inlet check needs to be cut off so as to not interfere with the float
 

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Looks like varnished fuel kind of, although it's odd that it's in chunks. Are you using ethanol-blend fuel? I know some of the carburetor kits are not alcohol safe. It's possible the crystals could be dissolved gasket material. Might be something from manufacturing of the new components as well. Maybe run some Seafoam through the system to help clean it and see if that goes away.
 

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please don't use sea foam snake oil

Hmm, sorry if that hits a hot button. I have used Seafoam with pretty good results in the crankcase and fuel system. I don't think it's magic, but I really don't think it does any harm. There are some pretty good and compelling YouTube videos that subjectively test Seafoam for removal of carbon deposits and to quiet noisy lifters. I think it's basically an oil-based solvent, so probably no worse than any other product that we use on cars/engines, etc. Anyway, I'll keep my opinions to myself, I guess, but that seems to defeat the purpose of a forum.

Peace.
 

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Hey I was just messing with you man.
 

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Discussion Starter #9
It’s not sea foam, or any additives. Just straight 93 octane, Sunoco ethanol 10%. I have ordered another rebuild kit from Mikes Carbs. They say ethanol friendly kits. So no one else has this issue? Weird.
when I touch the crystals it turns to powder. So the crystals grow as it evaporates. Float bowls are open to the air through vent tubes. But it shouldn’t happen so fast.
No ideas????
 

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You know, aluminum corrosion appears as a white powdery residue. It’s possible that this is the result of some moisture that is in, or being drawn in to your carburetor or fuel system. Perhaps the color of the corrosion products is being altered by absorbing gasoline. Just an idea, and a total guess...hopefully the Illuminati will allow it.

Are you running a carb spacer? I know many people leave those off for various reasons, but sometimes that results in an increased risk of percolation or fuel-boil. That can happen especially easily with ethanol-blend fuels, and right after shut-down when heat soaking happens and the underhood temps rise. It could be that most of your fuel is evaporating shortly after you park it, and so will be bone-dry in a couple weeks. Spacers at least put a little separation between the hot intake and the fuel bowls, and many of the FE variants have coolant passages for some amount of additional temperature control. On top of the faster evaporation and potential incompatibility with rubber fuel-system parts, ethanol does dissolve water, so it does have some degree of moisture attracting potential. These are the reasons I try to avoid it. I’m fortunate that I can still buy non-ethanol here in Iowa (ironic, as our state is a major producer). I know it’s not that way everywhere.

By the way, I was thinking that the lots from Mike’s are not all alcohol-safe, but you could upgrade to that if you specified? That may have changed, or I’m misremembering. Anyway, I’ll be interested to hear what you discover the fix to be.
 

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You know, aluminum corrosion appears as a white powdery residue. It’s possible that this is the result of some moisture that is in, or being drawn in to your carburetor or fuel system. Perhaps the color of the corrosion products is being altered by absorbing gasoline. Just an idea, and a total guess...hopefully the Illuminati will allow it.

Are you running a carb spacer? I know many people leave those off for various reasons, but sometimes that results in an increased risk of percolation or fuel-boil. That can happen especially easily with ethanol-blend fuels, and right after shut-down when heat soaking happens and the underhood temps rise. It could be that most of your fuel is evaporating shortly after you park it, and so will be bone-dry in a couple weeks. Spacers at least put a little separation between the hot intake and the fuel bowls, and many of the FE variants have coolant passages for some amount of additional temperature control. On top of the faster evaporation and potential incompatibility with rubber fuel-system parts, ethanol does dissolve water, so it does have some degree of moisture attracting potential. These are the reasons I try to avoid it. I’m fortunate that I can still buy non-ethanol here in Iowa (ironic, as our state is a major producer). I know it’s not that way everywhere.

By the way, I was thinking that the lots from Mike’s are not all alcohol-safe, but you could upgrade to that if you specified? That may have changed, or I’m misremembering. Anyway, I’ll be interested to hear what you discover the fix to be.
+1

I've seen this plenty of times with old carbs and old fuel sitting, it's moisture/old fuel causing corrosion. From your pictures you can see that the carburetor has had a problem in the past with water and or ethanol eating the bowl as you can see the pits in the aluminum and discoloration. You may have excessive water in your fuel as alcohol laden fuel is hygroscopic and absorbs it.

Good Luck
 

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There are several "Anti-Knock" compounds that use Iron Compounds in the formula.......causes Red Deposits on spark plugs and leaves a Red Residue in Carb Bowls.........hurts nothing but kinda alarming when ya see 'em!! ;)
 

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Discussion Starter #14
Rebuilt the carb, cleaned it out, soaked it , washed it, air blowed it. Put it back together with Mikes Carb rebuild kit. Installed it and took the wife for a ride. Now it runs great. Started right up, even after the drive when it was hot. Secondaries opened up, 67 foot one wheel peel. Idles great. So what ever those crystals were, they were causing havoc. Let’s just hope they don’t come back.
thanks for everyone’s opinions and help.
JIM
 
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